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Hindawi Publishing CorporationBioMed Research InternationalVolume 2013 Article ID 382184 20 pageshttpdxdoiorg1011552013382184

Review ArticleEfficient Hepatic Delivery of Drugs Novel Strategiesand Their Significance

Nidhi Mishra1 Narayan Prasad Yadav1 Vineet Kumar Rai1 Priyam Sinha1

Kuldeep Singh Yadav1 Sanyog Jain2 and Sumit Arora2

1 Herbal Medicinal Products Department CSIR-Central Institute of Medicinal and Aromatic Plants (CSIR-CIMAP)Lucknow 226015 India

2 Centre of Pharmaceutical Nanotechnology Department of Pharmaceutics National Institute of Pharmaceutical Educationand Research (NIPER) Sector 67 SAS Nagar Mohali Punjab 160062 India

Correspondence should be addressed to Narayan Prasad Yadav npyadavgmailcom

Received 24 April 2013 Revised 14 August 2013 Accepted 25 August 2013

Academic Editor Umesh Gupta

Copyright copy 2013 Nidhi Mishra et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Liver is a vital organ responsible for plethora of functions including detoxification protein synthesis and the production of bio-chemicals necessary for the sustenance of life Therefore patients with chronic liver diseases such as viral hepatitis liver cirrhosisand hepatocellular carcinoma need immediate attention to sustain life and as a result are often exposed to the prolonged treatmentwith drugsherbal medications Lack of site-specific delivery of these medications to the hepatocytesnonparenchymal cells andadverse effects associated with their off-target interactions limit their continuous useThis calls for the development and fabricationof targeted delivery systems which can deliver the drug payload at the desired site of action for defined period of timeThe primaryaim of drug targeting is to manipulate the whole body distribution of drugs that is to prevent distribution to non-target cellsand concomitantly increase the drug concentration at the targeted site Carrier molecules are designed for their selective cellularuptake taking advantage of specific receptors or binding sites present on the surface membrane of the target cell In this reviewvarious aspects of liver targeting of drug molecules and herbal medications have been discussed which elucidate the importance ofdelivering the drugsherbal medications at their desired site of action

1 Introduction

In the last decade significant advances have been made inthe development of plant-based hepatoprotective drugsmostly because of their lower toxicity and a multi-factorialapproach to restoring health seeking equilibrium betweenmind body and environment and placing a greater emphasison the multidimensional elements of health than on path-ology alone Along with drugs phytomedications haveincreasingly been prescribed for the treatment of a number ofdiseases However phytotherapeutics needs a scientificapproach to deliver the components in a sustained mannerso as to increase patient compliance and avoid repeatedadministrationThis can be achieved by designing novel drugdelivery systems (NDDS) for herbal constituents in additionto the drugs already available in the market Novel drugdelivery systems not only reduce the repeated administration

(due to its sustained-release properties) to overcome non-compliance but also help to increase the therapeutic value byreducing toxicity increasing the bioavailability stability andtargetability to a specific cell or organ (due to its subcellularsize) For a long time herbal medicines were not consideredfor development as novel formulations owing to the lackof scientific justification and processing difficulties such asstandardization extraction and identification of individualdrug components in complex polyherbal systems Howevermodern phytopharmaceutical research solves the scientificneeds for herbal medicines as in modern medicine whichgives way for developing novel formulations such as nanopar-ticles microemulsions matrix systems solid dispersionsliposomes and solid lipid nanoparticles

However for delivery to specific cell type of liver noveldrugs delivery system for herbal drugs still needs somemodification such as attaching of ligand or targeting moiety

2 BioMed Research International

which will recognize and interact with specific cell type ofliver In the present review we enumerate all the methods forattaching targeting moiety to delivery system and differentfactors which could be taken into account while designingNDDS for liver cell which will be of immense importance innear future The review elucidates the importance of deliveryof both the drugs and herbal medications to the liver so as toensure successful treatment outcomes

2 Morphological Study of Liver

Before discussing the different methods of targeting it isnecessary to understand the morphology of liver (especiallyvascular supply) and molecular scale of the target tissue inorder to design a novel drug delivery system rationally

The liver engages numerous metabolic immunologicaland endocrine functions It receives blood (oxygenated anddeoxygenated) from the gut and heart via the portal vein andhepatic artery respectively Blood circulates through a per-meable discontinuous capillary network term as the sinusoidsto reach the central and hepatic veinsThe sinusoids are smallblood vessels (5 to 10120583m wide) between the radiating rowsof hepatocytes having fenestrations of size 100ndash150 nm(depending on the type of animal species)They allow almostunrestricted passage of plasma components to the perisinu-soidal space where the cords of parenchymal cells called ashepatocytes are situated Inside the sinusoid capillaries theKupffer cells are responsible for phagocytic activity of the liver[1 2]

21 Phagocytosis in Kupffer Cells Phagocytosis occurs afterthe multivalent drug delivery system comes in contact withthemacrophagewhere they spread the cellmembrane aroundthe particles to engulf them Macrophages recognize thedelivery systems via the recognition of opsonins present overthem or through interactionwith scavenger receptors presenton Kupffer cells After ingestion phagocytic vesicle (phago-somes) coalesces with intracellular organelles containingdigestive proteins having acidic internal pH to mature intophagolysosomes and to degrade the internal part of the deliv-ery system The delivery system is then eliminated by exo-cytosis after degradation or is sequestered in residual bodieswithin the cell if it cannot be digested [3 4]

22 Macrophages Interaction with the Delivery System Thefollowing factors should be taken into account while dis-cussing the interaction of macrophages with the deliverysystem

Size and Radius The interaction between the macrophagesand delivery system could be influenced by the size and radiusof curvature of delivery system Generally a diameter of1ndash3120583m (in vitro limit is 20120583m) is sufficient for interaction asKupffer cell has ruffled surface Too small particles co-operateless with the cell membrane and gain entry into the cellthrough the other side like pinocytosis or endocytosis whilethe larger particle fails to contact with the cell membrane

Branch of hepaticportal vein

Central vein

Bile duct

Sinusoid

Liver cells

Figure 1 Microscopic view of liver cells

Shape The shape has great impact on the interaction ofdelivery system and macrophages For larger particles elon-gated shapes promote interaction while for smaller particleshape influences the speed of internalization and the differentpathways used to enter the cells Some studies have shownthat in comparison to their spherical shape nonsphericalparticles are steered into distinctive tissue distribution pat-terns by hydrodynamic forces in the bloodstream for exam-ple filomicelles with very high aspect ratios (gt10) and lon-gitudinal lengths around 10 120583m achieve considerably longercirculation times than spherical particles

Flexibility and DeformabilityThese are other parameters thatalso influence the interaction and distribution The flexi-bility of smaller hydrophilic delivery system (approximately200 nm) was found to affect in vitro kinetics and internaliza-tion pathways in macrophages [5] and other nonphagocyticcells [6] In vivo the flexibility and deformability of deliverysystems have great impact on their tissue distribution andretention for example RBC

Surface Properties These properties influence interaction in acomplex manner Positive charges on the surface of deliverysystem have deleterious effect on circulation times whereascontrary findings are reported regarding the impact of neg-ative charge For example He et al [7] studied the effectsof particle size and surface charge on cellular uptakebio-distribution and concluded that in vivo biodistribution ofnanoparticles (NPs) with slight negative charges and particlesize of 150 nm tended to accumulate in tumormore efficientlywhile Funato et al and Nishikawa et al [8 9] reportedthat negatively charged liposomes have a shorter half-life inthe blood Figure 1 provides a microscopic view of the liversurface

3 Essential Attributes for Designing DeliverySystems for Liver Targeting

For a therapeutic moiety to exert its desired effect it needsto be in physical contact with its physiological target such asa receptor present on liver cells Site-specific drug delivery

BioMed Research International 3

ensures that such interactions take place only in the desiredanatomical location of the liver therefore it must fulfil thefollowing criteria (i) it must be able to cross the anatomicalbarriers such as those of stomach and intestine (ii) shouldbe recognized selectively by the receptor present on liver cellsuch as asialoglycoprotein (iii) exogenously delivered ligandfor targeting should compete with the endogenously pro-duced ligand (iv) fabricated delivery system must be non-toxic biocompatible biodegradable and physico-chemicallystable in the liver cells either in vivo or in vitro (v) it shouldhave uniform sinusoid capillary distribution (vi) should havecontrollable and predictable rate of drug release so that onlytherapeutic amount of drug is released to the liver cells(vii) drug release should not affect the drug distribution(viii) it should showminimal drug leakage during its passagethrough stomach intestine and other parts of the body (ix)carrier used for encapsulating the herbal drugs must be elim-inated from the body without imparting any sign of toxicityand no carrier should induce modulation of diseased stateand (x) lastly preparation of drug delivery system shouldbe easy or reasonably simple reproducible and cost-effective

31 Pharmacokinetic Considerations Pharmacokinetics alsoplays an important role in developing novel delivery systemsof herbal drugs for liver since the introduction of this toolenables us to quantitatively predict the disposition of drugsafter modification Some pharmacokinetic conditions mustbe fulfilled to achieve a successful performance by site-select-ive drug-carrier delivery systems which are as follows

311 Rate of Elimination of Drug-Carrier Conjugate Drug-carrier conjugate should not be removed too rapidly from thesystemic circulation rather should be removed in a controlledmanner All the nonspecific interactions between drug-car-rier conjugate and the environment of the systemic compart-ment need to be eliminated during designing and develop-ment of targeted delivery systemsThe carrier should have theability to restrict all unwanted interactions between the drugand the physiological environment until drug is released atthe target site [10 11]

312 Rate of Release of Free Drug at the Non-Target Site Therelease of drug at the non-target site could nullify any benefitsthat might potentially come from delivering the drug to thetarget site This is because the amount of drug reaching at thenonspecific sites may cause toxicity owing to its high concen-tration

313 Rate of Delivery of Drug-Carrier Conjugate to the TargetSite If the drug-carrier conjugate reaches the target site tooslowly the supply of free drug might never be sufficient togenerate the concentration required to elicit the desired ther-apeutic effect at the site of action The total amount of drugdelivered (ie the area under the curve in a drug concen-tration versus time plot for the target site) is irrelevant if atany time the free-drug concentration at the target site doesnot reach its pharmacologically effective level Delivery of thedrug-carrier conjugate to the target organ may not guarantee

that an adequate amount of the free drug will be available atthe actual target

314 Rate of Release of FreeDrug at the Target Site Thecapac-ity of the drug delivery system selected for the release of freedrug from the conjugate should be considered It needs to besuitable for processing the entirety of the drug-carrier con-jugate arriving at the target site doing so at a rate that alsoensures drug accumulation at target site

315 Rate of Removal of Free Drug from the Target Site Drugsthat benefit most from target selective delivery are those thatare retained at the site while acting on their target of actionTherefore drugs should be specifically designed to be usedwith target selective delivery systems and drug deliveryshould not be used for rescuing poorly performing existingdrugs Certain drug (eg DNA in gene therapy) needs to bedelivered into the cytoplasm therefore it would be preferen-tial for the release of the drug to take place within the cellsThis could lead to the enhanced retention of the drug in closeproximity to its target Furthermore an increased rate ofelimination of free drug from the central compartment tendsto increase the advantage brought about as a result of drug tar-geting but also increases the required rate of input (of the drugcarrier) to maintain a therapeutic effect [12]

316 Rate of Elimination of the Drug-Carrier Conjugate andFree Drug from the Body For optimal targeting eliminationof the complete drug-carrier system should be minimalThese systems are too large to be eliminated via the kidneys[13] Consequently the liver is mainly responsible for theremoval of drug conjugates from the circulation The rate ofelimination of free drug from the systemic circulation shouldbe rapid relative to its rate of transfer from the target site to thecentral compartment of the bodyThis way the drug-deliverysystemwill achieve a decrease in the drug-associated toxicity

4 Formulation Aspects of LiverTargeting of Drugs

Normally most of the drugs achieve high hepatic concen-tration still their targeting is necessary because liver is themajor organ in the body equipped for uptake detoxificationmetabolic transformation and excretion of xenobiotics intobile by means of carrier-mediated mechanism As a conse-quence most of the drugs are rapidly cleared from the bloodand display high first pass clearances by the liver Howeverit should be realized that the total hepatic uptake predom-inantly depends on hepatocytes whereas Kupffer cells largelycontribute to hepatic uptake of particulate material There-fore the drugs that enter the liver as such or in the form ofcovalent carrier conjugates will not necessarily reach therequired cell type Moreover if drugs are accumulated in theliver their residence time in the organ is influenced by thefactors discussed under macrophages interaction with deliv-ery system and pharmacokinetic consideration Thus thechallenge is to obtain selective accumulation of drugs in onespecific cell type and to sustain intracellular levels for longer


Table 1 Receptors present on various hepatic cell and may be used for drug targeting [25]

Hepatocytes Kupffer cells Endothelial cell Hepatic stellate cellsAsialoglycoproteinreceptor (ASGP-R) MannoseN-acetyl glucose amine R MannoseN-acetyl glucose

amine R M6PIGF II R

HDL-R Galactose particle R Scavenger R (Class A1 and A11) 1205722macroglobulin R

LDL-R Galactose specific R Fc R immune complexes Ferritin R

IgA-R Fc R (immune complexes opsonizedmaterial)

Matrix compound (hyaluronanfibronectin denatured collagenPIIINP)

Uroplasminogen R

Scavenger R (Class BI) Scavenger R (Class AI BI BII MARCOCD36 and macrosialin) Thrombin R

Transferrin R LDL R matrix compounds (fibronectin)RBP R matrix compounds(intregrin collagen type VIfibronectin CD44)

Insulin R Complement R (C3b and C1q) LPS R 1205722macroglobulin R

lowastR Receptor

period The target cellsreceptors within the liver for treat-ment and possible entry mechanisms in these cells have beenidentified (Table 1) Hepatocytes are functional units respon-sible for most of the metabolic and secretory activities of theliver Small size delivery system that is 150 nm avoid captureby Kupffer cells and can diffuse out of the sinusoids throughthe fenestrations and reach the hepatocytes plates Thesecells can take up colloidal carrier system through pin-ocytosis and receptor-mediated endocytosis Improved deliv-ery (enhanced localization) to the parenchyma is achievedwith small size delivery system that is le50 nm that can dif-fuse deeper in the space of disse [2 14 15] Specific targeting ofhepatocyte receptors can also be achieved The most com-monly exploited target is the asialoglycoprotein receptor(ASGP-R) that recognizes carbohydrates (mainly galactoseand N-acetylgalactosamine) with variable affinity [16] SinceASGP-Rpositive vesicles transit to the lysosomes the increas-ingly acidic and oxidative conditions in organelles after endo-cytosis must be taken into account when targeting this path-way Similarly the upper size threshold for the internalizationof colloids via ASGP-R seems to be situated below 90 nm [17]This limits the type of carrier system which can be deliveredthrough this route Another approach consists of decoratingdelivery systemwith hepatocytes targeting lipoproteins eitherbefore administration [18 19] or in situ after injection [20 21]Although effective targeting to hepatocytes can be achievedthe ubiquitous nature of lipoprotein receptors in different tis-sues can lead to nonspecific distribution and subsequent sideeffects [22] Finally because non-parenchymal liver cells alsopossess physiological and pathological functions their tar-geting can sometimes be desirable Scavenging receptors canserve to target Kupffer and endothelial cells [21 23] whilecoupling with vitamin A on the surface of colloidal deliverysystem revealed an effective way of delivering active to stellatecells that play a fundamental role in liver fibrosis [24]

41 Different Aspects of Formulation Design for Targetingto Liver There are various methods for coupling of ligand

Polymer shell

DrugPolymer core

Cell surface targeting moiety

Polymer

Antibody

Figure 2 Drug delivery system encapsulating drug grafted withtargeting moiety

molecule on drug delivery system so that drug-carrier systemcan be targeted to liver cell via receptor ligand processes(Figure 2) Some of them are discussed below and which canalso be used for targeting of herbal drugs to liver

Different methods for coupling of ligand molecule ondrug delivery system (Figure 3) are

(a) coupling of targetingmoieties on preformed nanocar-riers

(b) coupling of targeting moieties by the post-insertionmethod

(c) coupling of targeting moieties by the AvidinBiotincomplex

(d) coupling of targeting moieties before nanocarriersformulation

411 Coupling of Targeting Moieties on Preformed Nanocarri-ers Thedesign of nanocarriers possessing targetingmoietieson their surface can be realized by coupling of the selectedmolecule to the surface of preformed nanocarriers usingvarious methods of the coupling chemistry domain Consid-erable amount of work has been done on the coupling ofantibodies on the surface of preformed nanocarriers usingmaleimide groups located on their surface Sugars have been


Drug Nanospheres

Grafting Conjugation of targeting ligand

PolymerLigand

Linker

++

+

(a)

Incubation

Micelle with targeting moiety

Delivery system with targeting moiety

Micelle

Delivery system

Delivery system

+

(b)

Delivery system Avidin Biotin

Antibody

Receptor

(c)

Functionalized monomer

DrugDrug polymer conjugate

Conjugation of targeting ligand Polymerization

(d)

Figure 3 Different methods for coupling of ligand molecule on drug delivery system (a) Coupling of targeting moieties on preformednanocarriers (b) Coupling of targeting moieties by the post insertion method (c) Coupling of targeting moieties by the AvidinBiotincomplex (d) Coupling of targeting moieties before nanocarriers formulation

also widely used as targeting moieties Liang et al [26] haveprepared nanoparticles composed of (PGA-PLA) processinggalactosamide on their surfaces Cellular uptake study usingrhodamine-123 loaded PGA-PLA nanoparticle with conju-gated galactosamine indicated that galactosylated nanopar-ticles had a specific interaction with HepG2 cells via ligand-receptor (ASGP-R) recognition Viability of HepG2 cellstreated with different paclitaxel formulations showed that theactivity inhibiting the growth of cells by paclitaxel loadedgalactosylated PGA-PLA nanoparticles was comparable tothat of clinically available paclitaxel (Phyxol) while pacli-taxel loaded PGA-PLAnanoparticles displayed a significantlylower activity The authors concluded that the galactosylated

nanoparticles interacted in a specific manner with HepG2cells via a ligand-receptor (ASGP-R) recognition leading tointernalization of the drug carrier into HepG2 cells and re-lease of paclitaxel into the cytoplasm Biodistributions of theprepared nanoparticles in organs of normal mice and hepat-oma bearing nude mice showed that galactosylated nanopar-ticles had specific interactions with liverrsquos parenchymal cellsand HepG2 cells via ligand receptor recognition In addi-tion antitumor efficacy of the prepared nanoparticles onhepatoma bearing nude mice showed that paclitaxel loadedgalactosylated PGA-PLA nanoparticles have the higher effi-cacy in reducing the tumor size The results led the authorsto conclude that paclitaxel (TX) loaded galactosylated


PGA-PLA nanoparticles were mainly accumulated at thetumor site and the liver in contrast to a nonspecific accumu-lation of Phyxol

Gupta et al [27] reported that PLGA nanoparticles bear-ing HBsAg were prepared by double emulsion method andfurthermore lectin from Arachis hypogaea (peanut agglu-tinin) was anchored onto the surface of the HBsAg loadednanoparticles in order to enhance their affinity towards theantigen presenting cells of the Peyerrsquos patches They conclud-ed that the ligand-coupled nanoparticles demonstrated ap-proximately fourfolds increase in degree of interaction withthe bovine submaxillary mucin (BSM) as compared to plainnanoparticles

In another study Bibby et al [28] reported the bio-distri-bution and pharmacokinetics of a cyclic RGD-doxorubicin-nanoparticle (NP) formulation in tumor-bearing mice TheNP core was composed of insulin multimethacrylate with atargeting peptide cyclic RGD covalently attached to the NPsvia PEG-400 and revealed decreasing drug concentrationsover time in the heart lung kidney and plasma and accu-mulating drug concentrations in the liver spleen and tumordue to drug-receptor interaction as particle largely composedof carbohydrate the insulin derivative that is insulin multi-methacrylate (IMMA)

Stella et al [29] studied the design of poly(ethylene gly-col) (PEG)-coated biodegradable nanoparticles coupled tofolic acid to target the folate-binding protein In this studypreformed nanoparticles were conjugated to the activatedfolic acid via PEG terminal amino groups and purified fromunreacted products and the authors concluded that folate-linked nanoparticles represent a potential new drug carrierfor tumor cell-selective targeting

Coupling of a targeting moiety on the surface of prefor-med nanocarriers has brought a significant improvement inthe designing of targeted drug delivery systems

412 Coupling of Targeting Moieties by the Post-InsertionMethod The modifications of preformed nanocarriers donot always lead to a controlled amount of bound targetingmoieties so other ways of coupling have been studied and themost important one is post-insertion method The post-insertion technique seems to be relatively simple leads to anappropriate level of stable ligand incorporation and is notcompromising for drug loading efficacy and drug release pro-file [30] The post-insertion consists of firstly preparing thedrug delivery system loaded with the selected drug parallelymicelles based on a mixture of functionalized PEG-lipid areprepared and the selected targeting moiety is coupled to itSecondly the targeting moiety is transferred frommicelles todrug delivery system by incubating both formulations Thepost-insertion technique seems to be simple and leads to theexpected site specific drug nanocarriers However number oftargeting moieties on carrier surface was not always welldefined and a drug leakage was observed during the incuba-tion procedure

Iden and Allen [31] prepared the stealth immunoliposo-mes (SIL) coupled to anti-CD19 by the post-insertion tech-nique and revealed that the in vitro binding and uptakeof PIL[anti-CD19] by CD19-expressing B-cell lymphoma

(Namalwa) cells were similar to those of SIL[anti-CD19] andboth were significantly higher than binding of non-targetedliposomes (SL) In addition no significant differences werefound between the respective in vitro cytotoxicities of doxo-rubicin-loadedPIL [anti-CD19] or SIL[anti-CD19] or in theirin vivo therapeutic efficacy in a murine model of human B-lymphoma Overall the results demonstrate that the post-insertion technique is simple flexible and effective meansfor preparing targeted liposomal formulations for clinicalapplications

413 Coupling of TargetingMoieties by the AvidinBiotin Com-plex Avidin is a basic glycoprotein (MW 68Kd) which hasa high affinity for the small (MW24Kd)water soluble vitaminbiotin Biotin can be conjugated to a variety of biologicalmolecules including antibodies and many biotin moleculescan be attached to a single molecule of protein The biotiny-lated protein can thus bind to more than one molecule ofavidin The strong avidin-biotin complex has been used tocouple targeting moieties on nanocarrierrsquos surfaces with theadvantage that no coupling chemistry is normally need-ed Bio-distribution of lactosyl-streptavidin (Lac-St 5molLacmol St) examined during period of several days showedrapid uptake by the liver and almost none by blood and othertissues Avidin and streptavidin were further subjected toan array of chemical modifications in an attempt to identifyother tissue specificities Chemical modification of lysine res-idues with trinitrophenyl (TNP) groups was found to abolishstreptavidin accumulation in the kidney and led to specificand long-term accumulation in the liver [32]

Ouchi et al [33] reported that the complexes preparedby mixing Biotin-triethyleneglycol-galactose (Bio-TEG-Gal)conjugate and fluorescein isothiocyanate (FITC)-labeledAv (feed molar ratio 4 1) and mixing Bio-TEG-Gal con-jugate Bio-TEG-TAMRAconjugate and FITC-labeledAv areinternalized into the hepatoma cells through a receptor-med-iated endocytosis mechanism Similarly Mamede et al [34]reported that the avidin-biotin system seems to have potentialas a carrier of oligo-DNA to the liver Zeng et al [35] reportedthe synthesis of disulfide-containing polyethylenimine (PEI-SS) from low molecular weight branched PEI and cystaminebisacrylamide (CBA) and then grafted with biotin Theobtained biotinylated PEI-SS was bioconjugated with avidinvia the biotin-avidin interaction to form a novel gene vec-tor biotinylated PEI-SSavidin bio conjugate (ABP-SS) Theresults confirmed that ABP-SS contributes to more cellularuptake of complexes in HepG2 cells Recently Marysael etal [36] as an alternative to directly targeting of necrotictissue using hypericin synthesized a conjugate of hypericinto biotin for use in a pretargeting approach Hypericin wasconjugated to biotin-ethylenediamine in a straightforwardcoupling method using n-hydroxysuccinimide and dicy-clohexylcarbodiimide It was concluded from analysis ofautoradiography images which show a higher accumulationof I-avidin in pretargeted compared to non-targeted tissue

414 Coupling of Targeting Moieties before Nanocarriers For-mulation Another efficient method for the introduction oftargeting moieties consists of coupling the selected molecule


at one end of a lipid or a polymer Such strategy can be inter-esting because the coupling chemistry is realized on lipid orpolymer Moreover a better control of amount of targetingmoieties on nanocarrier surface can be reached in theory byintroducing a well-defined mol of targeting moiety bearinga lipid or polymer in the formulation In contrast to othermethods firstly the targetingmoiety is attached to polymer atone of its ends and after that the drug is encapsulated inpolymer coupled with ligand molecule In this method thechances of leakage of drug molecule is very less as ligand iscoupled to polymer before the encapsulation process Byreviewing various literatures galactose has been used forselective delivery of various drugs encapsulated in nanoparti-cles using different polymersWang et al [37] prepared lipos-omes encapsulating doxorubicin and found that doxorubicinloaded galactosylated liposomes presented a high liver accu-mulation in comparison to doxorubicin loaded conventionalliposomes with a loading efficiency of more than 95 Suchhigh loading efficiency was attributed to positive charge andretention capacity of doxorubicin Furthermore the result ofintrahepatic distribution and competitive inhibition studyalso confirmed that galactose residues of doxorubicin loadedgalactosylated liposomes could be recognized by ASGP-R onthe surface of parenchymal cells leading to high liver accumu-lation of such targeted liposomes Jeong et al [38] synthesizedthe poly(gamma-benzyl L-glutamate) (PBLG)poly(ethyleneglycol) (PEG) diblock copolymer endcapped with galactosemoiety and characterized for study of liver specific targetingand concluded that HepG2 cells with ASGP-R are moresensitive to TX-loaded nanoparticles than free TX whereasP388 cells murine leukemia cell line and SK-Hep 01 humanhepatoma cell line without ASGP-R are less sensitive to TX-loaded nanoparticles than free TX suggesting that specificinteraction between HepG2 cells and galactose moiety of thenanoparticles occurred

Hattori et al [39] investigated the potency of the man-nosylated cationic liposomes (Man liposomes) and suggestedthat the targeted delivery of DNA vaccine by Man liposomesis a potent vaccination method for DNA vaccine therapyOpanasopit et al [40] reported that muramyl dipeptide(MDP) can be selectively targeted to liver non-parenchymalcell (NPC) including Kupffer cell (KC) using mannosylated-liposomes Tian et al [41] firstly modified the chitosan poly-mer with glycyrrhetinic acid and then prepared the nanopar-ticles of BSA and concluded that BSA could be entrapped intothe nanoparticles with the drug-loading ratio of 263 andthe encapsulation efficiency of 815 A sustained release over11-day period was observed in pH 74 in vitro RecentlyTian et al [42] showed that the CTSPEG-GA nanoparticleswere remarkably targeted to the liver and maintained highconcentration of drug for prolonged period of time

5 Novel MaterialsLigands Used forLiver Targeting

Different hepatic diseases involve different cells (namelyhepatocytes Kupffer cell hepatic stellate cell and sinusoidalendothelial cells hepatic carcinoma cell etc) Hence it is

important to design or select proper materials to target thesedifferent diseased cells In this section various novel materi-als used to enhance the targeting efficiency of drug deliverysystems to receptors in the liver have been discussed withappropriate cases

51 Hepatic Parenchymal Cell Targeting Materials

511 Asialoglycoprotein Receptor (ASGP-R) Targeting Materi-als This receptor is responsible for the clearance of glyco-proteins with desialylated galactose or acetylgalactosamineresidues from the circulation by receptor-mediated endocy-tosis

Galactose Ligand Galactosylated surface is an attractive sub-strate for hepatocyte culture because of the specific interac-tion between the galactose ligand and the asialoglycoproteinreceptor on hepatocytesThe density of galactose is one of theimportant parameters for the hepatocyte attachment as it is amajor determinant of the hepatocyte attachment morphol-ogy and functions as reported by Ashwell and Harford [43]a multisubunit receptor of hepatocytes is responsible forbinding galactose residues on desialylated glycoproteins andtriantennary molecules that bind to the lectin with higheraffinity than oligosaccharides lacking a third branch [44]

Kobayashi et al [45] investigated the effects of galac-tose densities in the galactose carrying PS derivative onmorphology differentiation and proliferation of hepatocytesThe results indicated that hepatocytes exhibited lower 3H-thymidine uptake under the roundmorphology on the highergalactose density and higher 3H-thymidine uptake under thespread morphology on the lower galactose density Ise et alreported that hepatocytes attached to galactose carrying PSbelow 20 ngmL coating density expressed low levels ofASGP-R and exhibited higher proliferative capacities thanabove 50 ngmL coating density [46]

The galactose ligand-ASGP-R interaction is not onlyinfluenced by the ligand density on the ECM but also by thespatial orientation of the ligand Cho et al [47] investigatedthe effect of galactose orientation on the attachment of hepa-tocyte to galactose carrying PS surface prepared by the Lang-muir-Blodgett (LB) technique It was found that the hepa-tocytes cultured on LB surface of the polymer even at thelow galactose concentration could well recognize galactosemoieties of the polymer owing to the galactose orientationsuggesting that the spatial microdistribution of the galactosein the ECM is important for the regulation of the celladhesion

Lactoferrin (Lf) It is a mammalian cationic iron binding gly-coprotein belonging Lactoferrin (Lf) a mammalian cationiciron-binding glycoprotein belonging to the transferrin (Tf)family [48] recently became increasingly attractive becauseof its multifunctional andmediating biological activities withLf receptors (Lf-R) [49 50] Formerly Lf-R was successfullyutilized as a targeting ligand for brain delivery due to thepresence of Lf receptor on blood brain barrier (BBB) [5152] Likewise many recent studies revealed that lactoferrincould bind tomultiple receptors on hepatocytes For instance


Wei et al reported Lf-PEGylated liposomes (PLS) as apromising drug delivery system for hepatocellular carcinomatherapy with lower toxicity and enhanced efficacy [53ndash56]It has been validated that Lf-R binds to ASGP-R with highaffinity [57 58] implying that Lf-R is a good ligand to ASGP-R binding With its specific binding Lf-R has been appliedto gene delivery successfully transferring genetic materialto the hepatocytes [59] These exciting evidences suggestedthat Lf-R might be a promising candidate for hepatocellularcarcinoma targeting due to its high affinity for ASGP-Rand developing a hepatic carcinoma targeting drug deliverysystem employing the ASGP-R targeting ability of Lf-R ishighly possible

Lacto Bionic Acid (LA) Ligand Kamruzzaman Selim et al[60] synthesized super paramagnetic magnetite nanoparti-cles which were surface modified with lactobionic acid (LA)to improve their intracellular uptake and ability to targethepatocytes and reported that LA-modified magnetite nano-particles have a great potential to be used as contrast agent forliver diagnosis Later in 2009 [61] beta-galactose carrying lac-tobionic acid (LA) was conjugated on the surface of mercap-toacetic acid coated cadmium sulfide nanoparticles (CSNPs)to ensure specific recognition of liver cells (hepatocytes) andto enhance biocompatibility and found that the uptakeamount of Lactobionic Acid-immobilized CSNPs into hepa-tocytes was higher than that of CSNPs andMaltotrionic acid-CSNPs

Asialofetuin (AF) Ligand AF a natural ligand is a glycopro-tein that possesses three asparagine-linked triantennary com-plex carbohydrate chains with terminal LacNAc (N-acet-yllactosamine) residuesThe expressed protein displays affin-ity to hepatocyte ASGP-R and is endocytosized by the cellsIts receptor dissociation constant is 200-fold lower than theglycoproteins with biantennary N-linked oligosaccharidechains Therefore it has been used as a competitive inhibitorto other polysaccharides that also have affinity to the recep-tors Dıez et al [62] synthesized cationic nanoparticles usingAF as ligand and concluded that targeted-NP2 particlesshowed a 5- and 12-fold higher transfection activity in theliver compared to non-targeted (plain) complexes

Soybean-Derived SG Ligand Soybean-derived SG is a residueextracted from soybeans Maitani et al [63] investigated theinteraction of liposomes surface-modified with soybean-derived sterylglucoside (SG) (SG-liposomes) with HepG2cells and concluded that SG-liposomes are potentially usefuldrug carriers to target the liver because the glucose residuemay work as a kind of ligand for ASGP-R Qi et al [64]studied hepatocyte-specific targeting technology by modi-fying cationic liposomes with soybean sterylglucoside (SG)and polyethylene glycol and found that CSGPEG-liposomesmediated gene transfer to the liver was an effective gene-delivery method for hepatocytes-specific targeting whichappears to have a potential for gene therapy of HBV infec-tions Later on Shi et al [65] constructed a liposomal livertargeting delivery system by adding soybean-derived steryl-glucoside (SG) to the cationic liposomes and concluded that

SGBrij-35 modified cationic liposomes are potentially usefuldrug carrier to the liver

512 Glycyrrhetinic Acid (GA) Receptor Targeting MaterialsGlycyrrhizin (GL) and glycyrrhetinic acid (GA) are the mainbioactive compounds of licorice and are widely used inmedicine for the treatment of many pathologies [16 17] suchas antiinflammatory antigastric antihepatitis antiallergicand antihepatotoxic effects Negishi et al [66] showed thatthere are specific binding sites for GL and GA on the cellularmembrane of rat hepatocytes and confirm that the number ofbinding sites for GA is muchmore than that for GL RecentlyWolfrum et al [19] prepared chitosan nanoparticles modifiedwith glycyrrhizin (CTS-NPs-GL) and confirmed that CTS-NPs-GL preferentially accumulated in the rat hepatocytes bya ligand receptor interaction Akinc et al [20] also found thatthe cellular uptake of liposomes modified with glycyrrhetinicacid by rat hepatocytes was 33-fold higher than that ofunmodified ones Although the liver cell targeting ability ofthe GA-modified polymers has been confirmed in vitro thereare no reports on the distribution of GA-modified materialsin vivo and on the presence ofGA receptors on humanhepaticcells Therefore it is necessary to investigate the distributionof GA modified carriers in vivo and their affinity for humanliver cellsThese studies would be of immense importance forthe development ofGAmediated liver-targeted drug delivery

513 Bile Acid Receptor Targeting Materials Bile acids andbile acid receptors are therapeutic targets in the developmentof drugs for the treatment of cholestatic and fatty liver dis-eases Clerc et al [67] determine the effect of exogenous unes-terified cholesterol provided in either artificial liposomes orLDL on bile salt and they concluded that taurocholate in-creased the exchange of cholesterol between liposomes orLDL and hepatocyte membranes Putz et al [68] examine thepossibility of targeting liposomes to hepatocytes via bile saltsthe bile salt lithocholyltaurine was covalently linked to aphospholipid and concluded that the attachment of bile saltsto the surface of hepatocytes opens up promising possibilitiesfor hepatocyte-specific drug delivery

52 Hepatic Non-Parenchymal Cell Targeting Materials

521 Mannose Receptor TargetingMaterials Mannose recep-tors are known to contribute to the defense mechanism ofmammals by endocytosis or phagocytosis of terminal manndashnose bearing exogenous materials Mannose a sugar mono-mer of hexose has several important biological roles includ-ing the glycosylation of proteins Unlike galactose interact-ions with asialoglycoprotein receptors on parenchymal livercells D-mannose is recognized by mannose receptor gener-ally present on non-parenchymal liver cells such as Kupffercells macrophages resident in the liver A mannose 6-phos-phate binding protein with a subunit and molecular size of215000 has been isolated from bovine liverThe expression ofmannose-6-phosphate on rat hepatic stellate cell is increasedduring liver fibrosis [69]


Jayasree et al [70] has prepared mannosylated chitosan-zinc sulphide nanocrystals and reported that prepared nano-bioconjugates through simple aqueous chemistry possessedhigh colloidal stability and strong fluorescence emission atsim600 nm Characterization using X-ray diffraction dynamiclight scattering scanning electron microscope atomic forcemicroscopy and Fourier transformed infrared spectroscopyrevealed that the bioconjugated particles were appropriatelyfunctionalized and stable with an average size of 150 nm Bio-conjugation with mannose provided specificity and targetedcellular labelling characteristics as demonstrated using KBcells which overexpress mannose receptors on their surface

Rieger et al [71] reported biodegradable polymeric nano-particles presented with mannose residue at their surface andtheir interaction with lectins The study concluded that pre-pared nanoparticles are expected to be specifically recognizedby mannose receptors which are highly expressed in cells ofthe immune system The targeting properties of these carriersystems combined with their potential adjuvant effects due totheir size in the range of 200ndash300 nm make them attractivecandidates as vaccine delivery systems

Kawakami et al [72] synthesized novel mannosylatedcholesterol derivative cholesten-5-yloxy-N-(4-((1-imino-2-beta-D-thiomannosyl-ethyl)amino)butyl) formamide (Man-C4-Chol) in order to perform mannose receptor mediatedgene transfer with liposomes The results reported by themsuggest that plasmid DNA complexed with mannosylatedliposomes exhibits high transfection activity due to recogni-tion by mannose receptors both in vitro and in vivo

522 Hepatic Stellate Cell (HSC) Targeting Materials HSCsplay a central role in the progression of liver fibrosis Murielet al [73] investigate a suitable model of fibrosis in whichspontaneous reversion was minimal in order to study theability of silymarin silibinin colchicine and trimethylcolchi-cinic acid (TMCA) to reverse it and the model reported bythem was proved to be an excellent tool to study the ability ofdrugs to reverse fibrosis Suojanen et al [74] studied the tum-our growth and lymphatic micrometastatic by use of HSC-3-cell xenografted athymic nude mice and concluded that pep-tide gelatinase inhibitors are effective in inhibiting primarytumor growth but alone they do not prevent the spread of car-cinoma cells Table 2 provides compilation of different target-ing ligands employed for enhanced liver targeting

6 Targeting Strategies forDifferent Constituent Cells of Liverand Their Implications

The approaches to drug targeting described so far are notuniversal Direct administration of a drug into an affectedorgan or tissuemay be technically difficult Often the affectedareas do not differ much from the normal tissues in terms ofvascular permeability temperature and local pH value Mag-netic drug delivery also has limitations connected with bloodflow rate in the target The most natural and universal wayto impart the affinity toward the target to a nonspecific drugis the binding of this drug with another molecule (targeting

moiety) capable of specific recognition and binding at thetarget site The following substances can be used as target-ing moieties antibodies and their fragments lectins otherproteins lipoproteins hormones chargedmolecules mono-oligo- and polysaccharides and some low molecular weightligand such as sugars folic acids and peptides The parame-ters that determine the efficacy of drug targeting include thesize of target blood flow through the target number of bind-ing sites for the targeted drugdrug carrier within the targetnumber and affinity of targetingmoieties on a drugmoleculeand multipoint interaction of a drugdrug carrier with thetarget [88] Targeting moiety should be selected by keepingthe following points in mind (i) reaction between car-rier and moiety has to be simple fast efficient and repro-ducible (ii) coupling method has to yield to stable and non-toxic bond (iii) target recognition and binding efficiency ofthe coupled molecule have to be maintained (iv) targetednanocarriers have to be stable enough to present a circulationhalf-life allowing them to reach and interact with their site ofaction and finally (v) both the drug loading efficiency and thedrug release profile do not have to be significantly changed bytargeting moieties coupling reactions

61 Liver Cell Specific Targeting of Therapeutics Carrier mol-ecules are designed for selective cellular uptake taking advan-tage of specific receptors or binding sites present on the sur-face membrane of the target cell (Table 1) In various litera-tures hepatocytes targeting is synonymous for liver targetingand total liver uptake of a compound is measured withoutproper identification of the cell type that actually takes upthe drug Although hepatocytes represent more than 80 ofthe total number of resident hepatic cells uptake in other celltypes like Kupffer cells may occur as well and high uptakeof viruses antibodies or other biological compounds intothese cells often leads to complete degradation of such com-pounds which in some cases destroys their therapeutic activ-ity [13] Therefore for specific cell there should be specificdelivery system and ligand for targeting There may be fivedifferent cells types present in liver for active targeting ofdrug namely (i) hepatocytes (ii) Kupffer and sinusoidalendothelial cells (iii) hepatic stellate cells (HSC) (iv) bileduct epithelial cells and (v) hepatocellular carcinoma cellsTable 3 provides details of targeting approaches of drugs fordifferent constituent cells of liver

611 Hepatocytes Hepatocytes are generally the affected sitein various liver diseases like viral hepatitis (hepatitis A Bor C) alcohol-induced steatohepatitis (ASH) nonalcohol-induced steatohepatitis (NASH) and some genetic diseaseslike Wilsonrsquos disease hemochromatosis 120572-1 antitrypsin defi-ciency and several other metabolic disorders In order toreduce the side effect and enhance the therapeutic effect ofdrugsmanymethods for hepatocytes selective drug targetinghave been used in the past decades The most prevalent andthe effective strategies for targeting hepatocytes are men-tioned below

Asialoglycoprotein receptors (ASGP-R) are exclusivelyfound in hepatocytes located at the basolateral membrane


Table 2 Different ligand-based liver targeting approaches and conclusions

Drug Ligand Conclusion References

Doxorubicin GalactosamineGAL-DOX-AN is more effective in killing HepG2 cellthan DOX-AN [75]

Sugar charge-modified albumins Lactose mannoseStudy demonstrates that cell-specific delivery of sugar-and charge-modified albumins in fibrotic livers ispossible by coupling drugs to lactose and mannose

[76]

5-Iodo 21015840-deoxyuridine51015840-monophosphate Lactose

Bioavailability of 5-iodo 21015840-deoxyuridine51015840-monophosphate to the parenchymal liver cell isdramatically enhanced as a result of the conjugation ofthe antiviral drugs to lactosylated poly-L-lysine

[31 77]

DextranPermanent magnets andcalcein as a fluorescentmarker

Dextran magnetite (DM)-incorporated thermosensitiveliposomes would be useful in future cancer treatmentby magnetic targeting combined with drug release inresponse to hyperthermia

[78]

Tyr3-octreotide (TOC) a somatostatinanalogue

119873-palmitoyl cysteinylmoiety

Tyr3-octreotide (TOC) a somatostatin analogue showsenhanced therapeutic efficacy due to the liver-targetingeffect when coupled with119873-palmitoyl cysteinyl moiety

[79]

Methotrexate conjugated with bovineserum albumin (BSA) Galactose

Galactosylation of the carrier protein BSA significantlyenhanced the hepatocytes uptake and liver targetabilityof MTX

[80]

Prednisone acetate conjugated withpolycaprolactone-g-dextran polymer

Galactose and fluoresceinisothiocyanate

In vivo study indicated potential of prednisone acetateloaded galactosylated micelles in liver targeting [81]

Lactobionic conjugated with chitosan Azide (CHI-Az) or alkyne(CHI-Alk) groups

Lactobionic acid was conjugated with(CHI-AzCHI-Alk)-coated particles and the particlesexhibited hepatoma cell (HepG2) targeting behavior

[82]

Doxorubicin Soybean-derivedsterylglucoside (SG)

SG liposomes are potentially useful drug carriers to theliver because the glucose residue may work as a kind ofligand for asialoglycoprotein receptor (ASGP-R) onhepatocytes

[63]

Primaquine phosphate conjugatedwith polypropyleneimine (PPI)dendrimers

Coated peripherally withgalactose

The galactose coating of PPI dendrimers can make thePPI systems more effective and suitable for targeteddelivery of primaquine phosphate to liver

[83]

Paclitaxel conjugated with PLGA GalactosePaclitaxel loaded galactosylated PGA-PLAnanoparticles were mainly accumulated at the tumorsite and the liver

[84]

Rhein Vinegar-baked RadixBupleuri

Co-administration of rhein with VBRB efficient forliver targeting [85]

Streptavidin Trinitrophenyl (TNP)groups

The modified proteins could target high doses ofchemotherapeutic drugs (CDDP and 5-fluorouridine)to the liver through biotinyl dextran-derived carriers

[86]

5-Fluoro 29-deoxyuridine conjugatedwith lactosaminated poly-L-lysine Lactose

Poly-L-lysine-5-fluoro-21015840-deoxyuridine enters intoHepG2 cells through the asialoglycoprotein receptorand after intracellular penetration releases the drug ina pharmacologically active form

[87]

and therefore are in direct contact with the bloodstreamThehuman ASGP-R is a heterooligomer that is composed of twohomologous subunits (46 and 50 kDa) ASGP-R recognizeswith high affinity (KD in the nanomolar range) tri- and tetra-antennary N-linked sugar side chains with terminal galactoseresidues [109]Therefore galactose residue [17 110] or lactose

moieties [111] act as ligand and are coupled to proteins poly-mers or incorporated into the outer layer of delivery systemby one of the methods described above [16] Glycoproteinswith such glycosylation patterns are rapidly endocytosed bythe ASGP-R via clathrin-coated pits and vesicles In a similarcontext Shinoda et al [112] investigate specific interaction


Table 3 Cell specific hepatic targeting of different drugs

Type of cellreceptor Drug Further remarks References

Hepatocytes andasialoglycoproteinreceptor

Iododeoxyuridine (IDU)

By isolating liver cells after injection of theiododeoxyuridine (IDU) it was concluded thathepatic uptake occurred mainly inparenchymal liver cells

[89]

Hepatocytes Primaquine (PQ)The prepared emulsion could be developedinto a promising delivery system to target PQinto hepatocytes for vivax malaria therapy

[90]

Hepatocytes 5-Fluorouracil (5-FU) The drug-loaded ZPslowast could be efficientlytargeted at the liver by intravenous delivery [91]

Hepatic stellate cell(HSC)

Human serum albumin (HAS) modified withmannose6-phosphate (M6P)

M6P-modified albumins are taken up by HSCin fibrotic livers [92]

Hepatic stellate cell(HSC) MicroRNAs The study shows that there was direct target of

miR-181b in HSC-T6 cell [93]

Hepatic stellate cell(HSC) Antibody fragment

This antibody fragment may be an effectivemeans to target therapeutics to human hepaticstellate cells

[94]

Hepatic carcinoma cellGlycyrrhetinic acid-modified poly(ethyleneglycol)-b-poly(c-benzyl L-glutamate)(GA-PEG-PBLG) micelles

In vitro cell uptake results indicated that theintroduction of GA to the micelles significantlyincreased the affinity for human hepaticcarcinoma

[95]

Hepatic carcinoma cells Ribavirin nanoparticlesThe nanoparticles had effective growthinhibitory activity in hepG2 human hepatomacells

[96]

Hepatic carcinoma cell Rhodamine B with lactose as ligand The Lac-micelles will be an effectiveliver-targeting drug delivery system [97]

Kupffer cell(nonparenchymal cells)

Cholesten-5-yloxy-119873-(4-((1-imino-2-b-D-thiomannosylethyl)amino)butyl)formamide(Man-C4-Chol) into small unilamellar liposomesconsisting of cholesterol and distearoyl 3phosphatidylcholine (DSPC)

The results suggest that Man liposomes areeffective carriers for targeted delivery ofbioactive compounds to liver NPC

[40]

Hepatic stellate cell(HSC) Pentoxifylline

PTX-neoglycoproteinmannose-6-phosphate-albumin (M6PHSA)employing a novel type of platinum linkerwhich allows sustained delivery of the drug toHSC in the fibrotic liver

[98]

HepatocytesGalactosylated poly(ethyleneglycol)-chitosan-graft-polyethylenimine(Gal-PEG-CHI-g-PEI)

Together these results suggest thatGal-PEG-CHI-g-PEI which has improvedtransfection efficiency and hepatocytesspecificity both in vitro and in vivo may beuseful for gene therapy

[99]

Hepatocytes(asialoglycoprotein R)

Vitamin K5 and cytosine arabinoside usingpoly-L-glutamic acid and carboxymethyl dextran Effective targeting to hepatocytes [100]

Hepatic carcinoma cells Ursodeoxycholic acid (UA) modifiedprotein-lipid nanocomplex

The uptake of UA modified protein attached onthe nanoparticles was higher in hepaticcarcinoma cells (HepG2 and Bel 7402) than innormal liver cells

[101]

Hepatic carcinoma cell Human telomerase reverse transcriptase withpegylated immuno-lipopolyplexes

The vector pApoAI-shTERT was able to causeliver-specific and hTERT target-specificcytotoxicity and utilizing PILP to deliverpApoAI-shTERT is a promising strategy forliver-specific gene therapy

[102]

Nonparenchymal cells Mannosylated superoxide dismutase(SOD)

Increased delivery of SOD to nonparenchymalcell [103]

Hepatocytes Probucol liposomesHepatic uptake of liposomes should bemediated by asialoglycoprotein receptors beingprobucol incorporated in them

[104]


Table 3 Continued


Endothelium cell Paclitaxel (PTX)-loaded PEGylated PLGA-basednanoparticles grafted with RGD peptide

The targeting of anticancer drug to tumorendothelium by RGD-labeled NP is apromising approach

[105]

Hepatic stellate cells(HSC)

Cyclic Arg-Gly-Asp (RGD) peptides werecombined with maleimide-[poly(ethyleneglycol)]-12-dioleoyl-sn-glycero-3-phosphoethanolamine (MAL-PEG-DOPE)incorporated into stabilized liposomes

Targeted liposomes encapsulating HGF are apromising therapeutic modality in terms ofpromoting the remission of liver cirrhosis bypromoting collagen fiber digestion inhibitingcollagen production and promoting apoptosisof 120572-SMA-positive cells in rats with cirrhosis

[106 107]

Hepatocytes(asialoglycoproteinreceptor)

Super paramagnetic iron oxide (SPIO)nanoparticles

These data underline the potential applicationof Gal-ASPIO as a targeted ligand forASPGR-expressing cells in vivo

[107]

Hepatic carcinoma cell Doxorubicin loaded super paramagnetic ironoxide nanoparticles

DOX is a promising candidate for treating livercancer and monitoring the progress of thecancer using MRI

[108]

lowastZein nanoparticles

between galactose branched cyclodextrins (gal-CyDs) andhepatocytes in vitro and concluded that enzymatically synthe-sized gal-CyDs have specific interaction with the hepatocytesand may be useful as a drug targeting carrier to hepatocytesBut when efficient delivery of liposomes to hepatocytes wasperformed by targeting the galactose receptor on the surfaceof hepatocytes by lactosylceramide and asialofetuin then itwas found that lactosylceramide containing vesicles dis-tributed 48 in hepatocytes and 27 in non-parenchymalcells [113] It has been shown that a galactose receptor isalso located on Kupffer cells and involved in endocytosis orphagocytosis of particles with galactosyl residues [69] Thesereceptors are not evenly distributed on the surface of Kupffercells but clustered for the uptake of particles [70] Howeverthe galactose receptors on hepatocytes are evenly distributed[71] and can uptake ligand of up to 8 nm in diameter [72]Thus galactose moiety to target asialoglycoprotein receptormay not be a good target for the selective delivery of lipo-somes to hepatocytesTherefore the discovery of new ligandsfor liver targeting instead of the use of the conventional lig-ands is very important Another ligand for hepatocytes wasinvestigated by Lin et al [114] inwhich chitosan nanoparticlessurface was modified with glycyrrhizin (CS-NPs-GL) as newhepatocyte-targeted delivery vehicles and concluded that CS-NPs-GL could be a promising hepatocyte-targeted deliverycarrier But Negishi et al [66] showed that the number ofbinding sites for glycyrrhetinic acid (GA) is much morethan that for GL Therefore Tion et al [115] preparedglycyrrhetinic acid-modified chitosanpoly(ethylene glycol)nanoparticles for liver-targeted delivery and found that thecellular uptake of nanoparticles modified with glycyrrhetinicacid by rat hepatocytes was 19-fold higher than that ofunmodified ones In fact delivery of NDDS (like liposomesniosomes nanoparticles and phytosomes) and proteins tothe hepatocytes using ASGP-R as a target receptor was one ofthe first options for the cell specific delivery to the liver cellsalthough this has not led to any clinical application yet

612 Kupffer and Sinusoidal Endothelial Cells Kupffer andsinusoidal endothelial cells are localized within the space ofdisse in close vicinity of the hepatocytes [116] Kupffer cellsthe resident liver macrophages have long been considered asscavenger cells responsible for removing particulate mate-rial from the portal circulation However evidence derivedmostly from animal models indicates that Kupffer cells maybe implicated in the pathogenesis of various liver diseasesincluding viral hepatitis steatohepatitis alcoholic liver dis-ease intrahepatic cholestasis and activation or rejection ofthe liver during liver transplantation and liver fibrosis [117]Both the Kupffer and sinusoidal endothelial cells share manycharacteristics that can be relevant for the enhanced uptake ofdrug delivery systems by these cells They are endowed witha high phagocytic capacity and are as such an intrinsic partof the reticuloendothelial system (RES) This system plays anessential role in the regulation of the host defence system andbecause of this many foreign particles that accumulate inthese two cell types [118] Several of these diseases are treatedwith systemic immunosuppressive agents but there are manyarguments that favour a local downregulation of inflamma-tory processes within the liver rather than inducing systemicimmunosuppressive effects [119] Accumulation of therapeu-tic compounds in Kupffer and endothelial cells can either benonspecific or specific via designated receptors Drug deliv-ery systems like liposomesmicelles and viral particles end upin these cells via nonspecific uptake mechanisms due to theirlargest phagocytic activity [120]

In addition uptake in Kupffer and endothelial cells canalso bemediated by specific receptorsThese cells bind to neg-atively charged molecules via scavenger receptors that areabundantly expressed on theirmembrane [121 122] for exam-ple coupling of compound to lysine groups within the albu-min molecule removes positive charges from the moleculewhich creates a compound with a net negative charge thatmay serve as a ligand for scavenger receptors [123 124]

Targeting to Kupffer cell is directed through mannosereceptor using sugar moieties (like mannose and fucose)


which are coupled to delivery system while targeting tosinusoidal endothelial cell is possible using hyaluron receptoras the target receptor [5 6] Yamashita et al investigatedthatwhen liposomes surfacewasmodified by cetylmannoside(Man) then it could be useful for targeting to Kupffer cells[125] Melgert et al investigated that when dexamethasonewas coupled to mannosylated albumin it is selectively deliv-ered to the Kupffer cell [126]

613 Hepatic Stellate Cells (HSC) Hepatic stellate cells(HSC) play a crucial role in the development of liver fibrosisbecause of their prominent role in extracellular matrix pro-duction regulation of vascular tone and production of in-flammatory mediators such as transforming growth factor-b(TGF-b) and platelet-derived growth factor (PDGF) Duringfibrosis in particular these three processes are dearrangedAta certain point in the whole process the HSC perpetuate thefibrogenesis by creating several autocrine loops thus main-taining the process evenwithout contribution of the other celltypes Therefore these cells are major target for antifibroticdrugs [127ndash131] The first target receptor chosen was themannose-6-phosphate (M6P)insulin-like growth factor II(M6PIGFII) receptor because it was reported to be highlyunregulated on the cell membranes of activated HSC HSAwas modified with the sugar mannose-6-phosphate [132]More importantly the major part of the hepatic content wasfound in the HSC Mannose-6-phosphate hepatic stellate cell(M6P-HSA) bound in particular to the activated HSC and arapid internalization of the protein occurred via a receptor-mediated endocytotic route Greupink et al [133] showed thattargeted delivery of coupled mycophenolic acid to theHSC-selective drug carrier mannose-6-phosphate modifiedhuman serum albumin results in a decrease in HSC activa-tion making it the first drug that is successfully delivered tothis cell type Adrian et al [134] confirmed that M6P-HSA-liposomes can be efficiently targeted to non-parenchymalcells including HSC In addition two other HSC selectivecarriers were found Instead of the derivatisation of albuminwith specific sugars albumin was now modified with cyclicpeptide moieties (minimized proteins) that represented thebinding domains of cytokinesgrowth factors responsible forbinding to the activated HSC for example pentoxifylline is apromising drug that have been benefited from drug targetingstrategies [7 135ndash138]

Not only drugs but genetic materials are also of interestto be specifically targeted to HSC Gene therapy is an elegantway to correct genetic deficiencies or to induce the produc-tion of essential proteins in a certain cell type Adenoviral orlipid based nonviral vectors are alternatives to deliver genesand antisense material to cells [139ndash144] A few reports ongene delivery to the cirrhotic liver or to HSC have appearedin the past few yearsmostly using adenoviralmediated trans-duction methods Yu et al [145] reported a hepatic deliveryof neuronal nitric oxide synthase (NOS) which resulted in areduction of the intrahepatic resistance and portal pressurein in vivo models of liver fibrosis Qi et al [146] delivered adominant-negative type II transforming growth factor-breceptor gene to the liver and found a blocking of transform-ing growth factor-b which attenuated the development of

liver fibrosis Other examples of gene delivery in the contextof liver fibrosis are the hepatic delivery of telomerase RNAby Rudolph et al [147] and of urokinase-type plasminogenactivator by Salgado et al [148] and many more but withoutclinical usefulness

614 Bile Duct Epithelial Cells Bile duct epithelial cells play akey role in the pathogenesis of several hepatic diseases [149]In primary biliary cirrhosis these cells are the target of anautoimmune disease leading to the destruction of small intra-hepatic bile ductsThe etiology is not yet clear but the chronicinflammatory reaction around bile duct epithelial cells ulti-mately leads to irreversible cirrhosis and end-stage of liverfailure

Cell specific delivery to this cell type is still in its infancyUntil very recently no drug carrier to this cell type wasdescribed Oja et al reported the expression of secretin recep-tors on cells of the biliary tract [150]This receptor appears tobe present on normal bile duct epithelial cells and ductulesand they suggested that this receptor may be used for tar-geting to cholangiocarcinomas for therapy or diagnosis of thisdisease because of very high receptor expression on thesecarcinoma cells [151]

615 Hepatocellular Carcinoma Cells Hepatocellular carci-noma (HCC) is one of the most common malignant tumorswhich can result from several liver diseases such as hepatitisB andC infectionsmetabolic liver diseases and nonalcoholicfatty liver diseases [152]Malignant transformation of hepato-cytes induced by viral factors and several other mediators inthe chronically inflamed area leads to hepatocarcinogenesisHCC is the sixthmost common cancer (inmale) and the thirdleading cause of cancer associated deaths in the world[153 154] In well-differentiated forms of HCC hepatocytesexpress the asialoglycoprotein (ASPG) receptor [155] Manydrug delivery systems have already been developed to deliverdrugs to this receptor using lactosaminated or galactosaminesubstituted drug carriers In particular polymers have beenapplied for the purpose of drug delivery to HCC [156ndash158]butmodified albumins have also been explored [159 160]TheASGP-receptor has also been employed as a target receptorfor the delivery of genes with antineoplastic effects to thehepatocytes by making complexes of plasmids and polymerscoupled to ASGP-receptor binding ligands [161] Also otherdrug delivery systems such as cationic liposomes virosomesand adenoviral vectors have been exploited for the deliveryof anticancer drugs and genes in HCC Cheng et al [162] syn-thesizedGC5-FUnanoparticles by combining galactosylatedchitosan (GC) material with 5-FU and tested its effect onliver cancer in vitro and in vivoThey conclude that sustainedreleases of GC5-FU nanoparticles are more effective attargeting hepatic cancer cells than 5-FU monotherapy in themouse orthotropic liver cancer mouse model In the sameyear Li et al [163] concluded that the encapsulation of tetran-drine (Tet) and TX into nanoparticles retain the synergisticanticancer efficiency of Tet and TX against mice hepatomaH22 cells Other researchers Zhou et al [164] synthesizedN-lactosyl-dioleoylphosphatidylethanolamine (Lac-DOPE)and evaluated as a liver-specific targeting ligand via ASGP-Rreceptors for liposomal delivery of doxorubicin and reported


that lactosylated liposomes are promising drug deliveryvehicles for hepatocellular carcinoma Recently Zhang et al[165] reported that mixed copolymer nanoparticles (NPs)self-assembled from 120573-cyclodextrin-grafted hyperbranchedpolyglycerol (HPG-g-CD) and lactobionic acid (LA)-graftedhyperbranched polyglycerol (HPG-g-LA) were utilized ascarriers for hydrophobic antitumor drug TX resulting inenhanced hepatocellular-carcinoma uptake of these nanopar-ticlesTherefore it was concluded that mixed copolymer NPsare efficient nanocarriers for hepatoma-targeted delivery ofpotent antitumor drugs

7 Expert Comments

As per the report given by the WHO approximately 1 in 12personsworldwide or some 500million people are livingwithchronic liver disease It is forecasted that liver diseases maybecome a higher ranked cause of death in coming decadesbecause of its complex pathogenesis which involves a varietyof cells (parenchymal and non-parenchymal) The literatureexpressed that more than 90 of therapeutic drug is uptakenby normal tissues whereas only 2ndash5 is uptaken by dis-eased cells and moreover the current available therapy forliver diseases lacks adequate specificity and efficacy To limitthe severe side effects of conventional therapy targeted deliv-ery systems have shown an attractive prospect and openeda door for the treatment of chronic liver diseases Hence toincrease the efficacy of drugs and decreasing their toxic sideeffects encapsulation of drug in a carrier system is a commonapproach to achieve passive targeting Nevertheless passivetargeting does not always lead to effective drug accumulationin a specific tissue or organ Therefore to increase the spec-ificity of interaction between drug delivery system (DDS) andtarget cells or tissues as well as to increase the amount of drugdelivery to the desired site of action active targeting isneeded Such active targeting can be obtained by coupling atargeting moiety to the DDS providing a selective and quan-titative accumulation of theDDS at the target site In this con-text the concept of active liver targeting is undergoing clinicaltrial study for example doxorubicin coupled with magnet(MTC-DOX) is expected to target liver tumors directly Oneof the recent approaches in which the drug is directly boundto a targeting moiety for example when norcantharidindirectly bound to galactose group resulted in higher entrap-ment efficiency and low toxicity still needs more focus to ex-plore Whatever the way selected for coupling targetingmoiety to a DDS the reaction has to be simple fast efficientand reproducible Both the drug loading efficiency and thedrug release profile do not have to be significantly changed bytargeting moieties coupling reactions Furthermore targetedDDS have to be nontoxic and stable enough to present a suf-ficiently long circulation half-life allowing them to reach andinteract at their site of action

It is also necessary to explore whether fabricated deliverysystem could also show the same targeting efficiency inhumans with chronic liver diseases as in animal models Effi-cient drug targeting to liver has certain limitations for med-ical applications efficacy safety and cost as well as regulatoryconcerns

Efficacy and safety of the developed formulations remainthe prime goals with which these are developed It is essentialthat the drug delivery vehicle should deliver the drug payloadat its intended site of action at a required rate An ideal car-rier should be inert and devoid of any harmful effects Anoth-er major restraint in designing the targeted delivery system isthe high cost whichmakes productivitymore difficult and thereduced ability to adjust the dosagesThis could be overcomeby encouraging the building of strong partnerships at thenational and international level among academic and indus-trial partners with multidisciplinary expertise Another hur-dle is receiving the approval from drug regulatory authoritiesof respective countries such as Food and Drug Administra-tion (FDA) in the USA European Agency for the Evaluationof Medicinal products (EMEA) in Europe and Pharmaceu-tical and Medical Device Agency KIKO (PMDA KIKO) inJapan due to long-term clinical trials owning to the lack ofsurrogate parameters to measure the effect of treatmentDuration of clinical trial can be reduced by coupling the radi-olabel substance or fluorescent dye to DDS This dual ap-proach that is the use of the same carrier for imaging andtreatment will speed up the clinical trial study as well asapproval from regulatory authorities

Therefore a lot of work remains to be done for the effi-cient targeting of drug to liver Next improvements will cer-tainly come from the introduction of newmaterials includingstimuli-responsive polymers to elicit the challenge of target-ing the drug to its specific site of action to retain it for the de-sired duration and to release it according to the correct timeschedule8 Conclusion

The pathogenesis of liver diseases involves a variety of cellswhich makes the delivery of drug complicated The mostimportant aspects to improve the treatment via hepatopro-tective drug are the design and synthesis of appropriate poly-meric material to target specific cells of liver Ingenious stud-ies are required in coupling and selection of targeting moietyso that they could be translated from the bench research tothe bedside We have reviewed various aspects of selectionof ligands and their coupling to drugpolymer which wouldpotentially target parenchymalnon-parenchymal liver cellsThe pharmacokinetic behaviour and physicochemical factorsrelated with delivery systems have been considered to be pri-marily responsible for the improved targeting and therapeuticeffectiveness therefore dealing with these factors during for-mulation development could lead to more promising treat-ments for acute andor chronic liver diseases These inves-tigations require thorough inspection as well as innovativeapproaches to bring them into the global market at affordableprice

Conflict of Interests

The authors declare that they have no conflict of interests

Acknowledgments

The authors are thankful to Council of Scientific and Indus-trial Research (CSIR) New Delhi India for providing


financial assistance to Nidhi Mishra as CSIR-SRF (Grantno 1111022K1011) and CSIR-Central Institute of Medicinaland Aromatic Plants (CSIR-CIMAP) Lucknow India forproviding necessary facilities under the project OLP-08

References

[1] T Abe T Masuda and R Satodate ldquoPhagocytic activity ofKupffer cells in splenectomized ratsrdquo Virchows Archiv A vol413 no 5 pp 457ndash462 1988

[2] E Wisse F Jacobs B Topal P Frederik and B De Geest ldquoThesize of endothelial fenestrae in human liver sinusoids implica-tions for hepatocyte-directed gene transferrdquo Gene Therapy vol15 no 17 pp 1193ndash1199 2008

[3] J A Champion A Walker and S Mitragotri ldquoRole of particlesize in phagocytosis of polymeric microspheresrdquo Pharmaceuti-cal Research vol 25 no 8 pp 1815ndash1821 2008

[4] W Jiang B Y S Kim J T Rutka and W C W Chan ldquoNano-particle-mediated cellular response is size-dependentrdquo NatureNanotechnology vol 3 no 3 pp 145ndash150 2008

[5] X Banquy F Suarez AArgaw et al ldquoEffect ofmechanical prop-erties of hydrogel nanoparticles on macrophage cell uptakerdquoSoft Matter vol 5 no 20 pp 3984ndash3991 2009

[6] J-O You and D T Auguste ldquoNanocarrier cross-linking densityand pH sensitivity regulate intracellular gene transferrdquo NanoLetters vol 9 no 12 pp 4467ndash4473 2009

[7] C He Y Hu L Yin C Tang and C Yin ldquoEffects of particle sizeand surface charge on cellular uptake and biodistribution ofpolymeric nanoparticlesrdquo Biomaterials vol 31 no 13 pp 3657ndash3666 2010

[8] K Funato R Yoda and H Kiwada ldquoContribution of com-plement system on destabilization of liposomes composed ofhydrogenated egg phosphatidylcholine in rat fresh plasmardquoBiochimica et Biophysica Acta vol 1103 no 2 pp 198ndash204 1992

[9] K Nishikawa H Arai and K Inoue ldquoScavenger receptor-mediated uptake and metabolism of lipid vesicles containingacidic phospholipids by mouse peritoneal macrophagesrdquo Jour-nal of Biological Chemistry vol 265 no 9 pp 5226ndash5231 1990

[10] P J Morgan S E Harding and K Petrak ldquoInteractions of amodel block copolymer drug delivery system with two serumproteins and myoglobinrdquo Biochemical Society Transactions vol18 no 5 pp 1021ndash1022 1990

[11] P Opanasopit M Nishikawa and M Hashida ldquoFactors affect-ing drug and gene delivery effects of interaction with bloodcomponentsrdquo Critical Reviews in Therapeutic Drug CarrierSystems vol 19 no 3 pp 191ndash233 2002

[12] A Boddy L Aarons and K Petrak ldquoEfficiency of drug tar-geting steady-state considerations using a three-compartmentmodelrdquo Pharmaceutical research vol 6 no 5 pp 367ndash372 1989

[13] K Petrak and P Goddard ldquoTransport ofmacromolecules acrossthe capillary wallsrdquo Advanced Drug Delivery Reviews vol 3 no2 pp 191ndash214 1989

[14] K-I Ogawara M Yoshida K Higaki et al ldquoHepatic uptakeof polystyrene microspheres in rats effect of particle size onintrahepatic distributionrdquo Journal of Controlled Release vol 59no 1 pp 15ndash22 1999

[15] T M Allen C Hansen F Martin C Redemann and A F Yau-Young ldquoLiposomes containing synthetic lipid derivatives ofpoly(ethylene glycol) show prolonged circulation half-lives invivordquo Biochimica et Biophysica Acta vol 1066 no 1 pp 29ndash361991

[16] J Wu M H Nantz and M A Zern ldquoTargeting hepatocytes fordrug and gene delivery emerging novel approaches and appli-cationsrdquo Front Biosci vol 7 pp d717ndashd725 2002

[17] P CN Rensen LA JM SliedregtM Ferns et al ldquoDetermina-tion of the upper size limit for uptake and processing of ligandsby the asialoglycoprotein receptor onhepatocytes in vitro and invivordquo Journal of Biological Chemistry vol 276 no 40 pp 37577ndash37584 2001

[18] P C N Rensen M C M Van Dijk E C Havenaar M K Bij-sterbosch J K Kruijt and T J C Van Berkel ldquoSelective livertargeting of antivirals by recombinant chylomicronsmdasha newtherapeutic approach to hepatitis BrdquoNatureMedicine vol 1 no3 pp 221ndash225 1995

[19] C Wolfrum S Shi K N Jayaprakash et al ldquoMechanisms andoptimization of in vivo delivery of lipophilic siRNAsrdquo NatureBiotechnology vol 25 no 10 pp 1149ndash1157 2007

[20] A Akinc W Querbes S De et al ldquoTargeted delivery of RNAitherapeutics with endogenous and exogenous ligand-basedmechanismsrdquo Molecular Therapy vol 18 no 7 pp 1357ndash13642010

[21] M K Bijsterbosch E T Rump R L A De Vrueh et al ldquoMod-ulation of plasma protein binding and in vivo liver cell uptakeof phosphorothioate oligodeoxynucleotides by cholesterol con-jugationrdquo Nucleic Acids Research vol 28 no 14 pp 2717ndash27252000

[22] K M Wasan D R Brocks S D Lee K Sachs-Barrable and SJ Thornton ldquoImpact of lipoproteins on the biological activityand disposition of hydrophobic drugs implications for drugdiscoveryrdquo Nature Reviews Drug Discovery vol 7 no 1 pp 84ndash99 2008

[23] S Kunjachan S Jose C AThomas E Joseph F Kiessling andT Lammers ldquoPhysicochemical and biological aspects ofmacro-phage-mediated drug targeting in anti-microbial therapyrdquo Fun-damental and Clinical Pharmacology vol 26 no 1 pp 63ndash712012

[24] Y Sato K Murase J Kato et al ldquoResolution of liver cirrhosisusing vitamin A-coupled liposomes to deliver siRNA against acollagen-specific chaperonerdquo Nature Biotechnology vol 26 no4 pp 431ndash442 2008

[25] H Harashima K Sakata K Funato andH Kiwada ldquoEnhancedhepatic uptake of liposomes through complement activationdepending on the size of liposomesrdquo Pharmaceutical Researchvol 11 no 3 pp 402ndash406 1994

[26] H-F Liang C-T Chen S-C Chen et al ldquoPaclitaxel-loadedpoly(120574-glutamic acid)-poly(lactide) nanoparticles as a targeteddrug delivery system for the treatment of liver cancerrdquo Bioma-terials vol 27 no 9 pp 2051ndash2059 2006

[27] P N Gupta S Mahor A Rawat K Khatri A Goyal and S PVyas ldquoLectin anchored stabilized biodegradable nanoparticlesfor oral immunization 1 Development and in vitro evaluationrdquoInternational Journal of Pharmaceutics vol 318 no 1-2 pp 163ndash173 2006

[28] D C Bibby J E Talmadge M K Dalal et al ldquoPharmacokinet-ics and biodistribution of RGD-targeted doxorubicin-loadednanoparticles in tumor-bearing micerdquo International Journal ofPharmaceutics vol 293 no 1-2 pp 281ndash290 2005

[29] B Stella S Arpicco M T Peracchia et al ldquoDesign of folicacid-conjugated nanoparticles for drug targetingrdquo Journal ofPharmaceutical Sciences vol 89 no 11 pp 1452ndash1464 2000

[30] D L Iden and T M Allen ldquoIn vitro and in vivo comparison ofimmunoliposomes made by conventional coupling techniques


with those made by a new post-insertion approachrdquo Biochimicaet Biophysica Acta vol 1513 no 2 pp 207ndash216 2001

[31] D L Iden and T M Allen ldquoIn vitro and in vivo comparison ofimmunoliposomes made by conventional coupling techniqueswith those made by a new post-insertion approachrdquo Biochimicaet Biophysica Acta vol 1513 no 2 pp 207ndash216 2001

[32] B Schechter R Arnon Y E Freedman L Chen and M Wil-chek ldquoLiver accumulation of TNP-modified streptavidin andavidin potential use for targeted radio- and chemotherapyrdquoJournal of Drug Targeting vol 4 no 3 pp 171ndash179 1996

[33] T Ouchi E Yamabe K Hara M Hirai and Y Ohya ldquoDesign ofattachment type of drug delivery system by complex formationof avidin with biotinyl drug model and biotinyl sacchariderdquoJournal of Controlled Release vol 94 no 2-3 pp 281ndash291 2004

[34] M Mamede T Saga T Ishimori et al ldquoHepatocyte targetingof 111In-labeled oligo-DNA with avidin or avidin-dendrimercomplexrdquo Journal of Controlled Release vol 95 no 1 pp 133ndash141 2004

[35] X Zeng Y-X Sun X-Z Zhang and R-X Zhuo ldquoBiotinylateddisulfide containing PEIavidin bioconjugate shows specificenhanced transfection efficiency in HepG2 cellsrdquo Organic andBiomolecular Chemistry vol 7 no 20 pp 4201ndash4210 2009

[36] T Marysael M Bauwens Y Ni G Bormans J Rozenski andP de Witte ldquoPretargeting of necrotic tumors with biotinylatedhypericin using 123I-labeled avidin evaluation of a two-stepstrategyrdquo Investigational New Drugs vol 30 no 6 pp 2132ndash2140 2012

[37] S-NWang Y-H Deng H Xu H-B Wu Y-K Qiu and D-WChen ldquoSynthesis of a novel galactosylated lipid and its applica-tion to the hepatocyte-selective targeting of liposomal doxoru-bicinrdquo European Journal of Pharmaceutics and Biopharmaceu-tics vol 62 no 1 pp 32ndash38 2006

[38] Y-I Jeong S-J Seo I-K Park et al ldquoCellular recognition ofpaclitaxel-loaded polymeric nanoparticles composed of poly(120574-benzyl L-glutamate) and poly(ethylene glycol) diblock copoly-mer endcapped with galactose moietyrdquo International Journal ofPharmaceutics vol 296 no 1-2 pp 151ndash161 2005

[39] Y Hattori S Kawakami S Suzuki F Yamashita and MHashida ldquoEnhancement of immune responses by DNAvaccination through targeted gene delivery usingmannosylatedcationic liposome formulations following intravenousadministration in micerdquo Biochemical and Biophysical ResearchCommunications vol 317 no 4 pp 992ndash999 2004

[40] P Opanasopit M Sakai M Nishikawa S Kawakami F Yam-ashita and M Hashida ldquoInhibition of liver metastasis by tar-geting of immunomodulators using mannosylated liposomecarriersrdquo Journal of Controlled Release vol 80 no 1ndash3 pp 283ndash294 2002

[41] Q Tian W Wang X He et al ldquoGlycyrrhetinic acid-modifiednanoparticles for drug delivery preparation and characteriza-tionrdquo Chinese Science Bulletin vol 54 no 18 pp 3121ndash31262009

[42] Q Tian C-N Zhang X-H Wang et al ldquoGlycyrrhetinic acid-modified chitosanpoly(ethylene glycol) nanoparticles for liver-targeted deliveryrdquo Biomaterials vol 31 no 17 pp 4748ndash47562010

[43] G Ashwell and J Harford ldquoCarbohydrate-specific receptors ofthe liverrdquo Annual Review of Biochemistry vol 51 pp 531ndash5541982

[44] J U Baenziges and D Fiete ldquoGalactose and N-acetylgalactos-amine-specific endocytosis of glycopeptides by isolated rathepatocytesrdquo Cell vol 22 no 2 part 2 pp 611ndash620 1980

[45] A KobayashiMGoto K Kobayashi and T Akaike ldquoReceptor-mediated regulation of differentiation and proliferation ofhepatocytes by synthetic polymer model of asialoglycoproteinrdquoJournal of Biomaterials Science Polymer Edition vol 6 no 4 pp325ndash342 1994

[46] H Ise N Sugihara N Negishi T Nikaido and T Akaike ldquoLowasialoglycoprotein receptor expression as markers for highlyproliferative potential hepatocytesrdquoBiochemical andBiophysicalResearch Communications vol 285 no 2 pp 172ndash182 2001

[47] C S Cho M Goto A Kobayashi K Kobayashi and T AkaikeldquoEffect of ligand orientation on hepatocyte attachment ontothe poly(N-p-vinylbenzyl-o-120573-D-galactopyranosyl-D-gluco-namide) as amodel ligand of asialoglycoproteinrdquo Journal of Bio-materials Science Polymer Edition vol 7 no 12 pp 1097ndash11041996

[48] Y Iwamaru Y ShimizuM Imamura et al ldquoLactoferrin inducescell surface retention of prion protein and inhibits prion accu-mulationrdquo Journal of Neurochemistry vol 107 no 3 pp 636ndash646 2008

[49] Y A Suzuki V Lopez and B Lonnerdal ldquoMammalian lacto-ferrin receptors structure and functionrdquoCellular andMolecularLife Sciences vol 62 no 22 pp 2560ndash2575 2005

[50] P PWard S Uribe-Luna andOM Conneely ldquoLactoferrin andhost defenserdquo Biochemistry and Cell Biology vol 80 no 1 pp95ndash102 2002

[51] R Huang W Ke Y Liu C Jiang and Y Pei ldquoThe use of lacto-ferrin as a ligand for targeting the polyamidoamine-based genedelivery system to the brainrdquo Biomaterials vol 29 no 2 pp238ndash246 2008

[52] H Chen L Tang Y Qin et al ldquoLactoferrin-modified proca-tionic liposomes as a novel drug carrier for brain deliveryrdquoEuro-pean Journal of Pharmaceutical Sciences vol 40 no 2 pp 94ndash102 2010

[53] M Wei Y Xu Q Zou et al ldquoHepatocellular carcinoma target-ing effect of PEGylated liposomes modified with lactoferrinrdquoEuropean Journal of Pharmaceutical Sciences vol 46 no 3 pp131ndash141 2012

[54] M Gorria X Tekpli M Rissel et al ldquoA new lactoferrin- andiron-dependent lysosomal death pathway is induced by benzo-[a]pyrene in hepatic epithelial cellsrdquo Toxicology and AppliedPharmacology vol 228 no 2 pp 212ndash224 2008

[55] D J Bennatt and D D McAbee ldquoIdentification and isolation ofa 45-kKa calcium-dependent lactoferrin receptor from rathepatocytesrdquo Biochemistry vol 36 no 27 pp 8359ndash8366 1997

[56] D J Bennatt Y Y Ling and D D McAbee ldquoIsolated rat hepat-ocytes bind lactoferrins by the RHL-1 subunit of the asialogly-coprotein receptor in a galactose-independent mannerrdquo Bio-chemistry vol 36 no 27 pp 8367ndash8376 1997

[57] DDMcAbee X Jiang andK BWalsh ldquoLactoferrin binding tothe rat asialoglycoprotein receptor requires the receptorrsquos lectinpropertiesrdquo Biochemical Journal vol 348 no 1 pp 113ndash1172000

[58] D DMcAbee D J Bennatt and Y Y L Yuan Yuan Ling ldquoIden-tification and analysis of a CA2+-dependent lactoferrin recep-tor in rat liver lactoferrin binds to the asialoglycoprotein recep-tor in a galactose-independent mannerrdquo Advances in Experi-mental Medicine and Biology vol 443 pp 113ndash121 1998

[59] A Pathak S P Vyas and K C Gupta ldquoNano-vectors for effi-cient liver specific gene transferrdquo International Journal of Nano-medicine vol 3 no 1 pp 31ndash49 2008

[60] K M Kamruzzaman Selim Y-S Ha S-J Kim et al ldquoSurfacemodification of magnetite nanoparticles using lactobionic acid


and their interaction with hepatocytesrdquo Biomaterials vol 28no 4 pp 710ndash716 2007

[61] KM Kamruzzaman Selim Z-C Xing H Guo and I-K KangldquoImmobilization of lactobionic acid on the surface of cadmiumsulfide nanoparticles and their interaction with hepatocytesrdquoJournal of Materials Science vol 20 no 9 pp 1945ndash1953 2009

[62] S Dıez G Navarro and C T de ILarduya ldquoIn vivo targetedgene delivery by cationic nanoparticles for treatment of hepato-cellular carcinomardquo Journal of Gene Medicine vol 11 no 1 pp38ndash45 2009

[63] Y Maitani K Kawano K Yamada T Nagai and K TakayamaldquoEfficiency of liposomes surface-modified with soybean-derived sterylglucoside as a liver targeting carrier in HepG2cellsrdquo Journal of Controlled Release vol 75 no 3 pp 381ndash3892001

[64] X-R Qi W-W Yan and J Shi ldquoHepatocytes targeting of cat-ionic liposomesmodifiedwith soybean sterylglucoside and pol-yethylene glycolrdquoWorld Journal of Gastroenterology vol 11 no32 pp 4947ndash4952 2005

[65] J Shi X-R Qi L Yang R Fei and L Wei ldquoLiver targeting ofcationic liposomes modified with soybean-derived sterylgluco-side in vitrordquo Yaoxue Xuebao vol 41 no 1 pp 19ndash23 2006

[66] M Negishi A Irie N Nagata and A Ichikawa ldquoSpecific bind-ing of glycyrrhetinic acid to the rat liver membranerdquo Biochimicaet Biophysica Acta vol 1066 no 1 pp 77ndash82 1991

[67] T Clerc V Sbarra D Botta-Fridlund et al ldquoBile salt secretionby hepatocytes incubated with bile salts and liposomes or lowdensity lipoproteinsrdquo Life Sciences vol 56 no 4 pp 277ndash2861995

[68] G Putz W Schmider R Nitschke G Kurz and H E BlumldquoSynthesis of phospholipid-conjugated bile salts and interactionof bile salt-coated liposomeswith cultured hepatocytesrdquo Journalof Lipid Research vol 46 no 11 pp 2325ndash2338 2005

[69] G G Sahagian J Distler andGW Jourdian ldquoCharacterizationof a membrane-associated receptor from bovine liver that bindsphosphomannosyl residues of bovine testicular beta-galactos-idaserdquo Proceedings of the National Academy of Sciences of theUnited States of America vol 78 no 7 pp 4289ndash4293 1981

[70] A Jayasree S SasidharanM Koyakutty S Nair andDMenonldquoMannosylated chitosan-zinc sulphide nanocrystals as fluo-rescent bioprobes for targeted cancer imagingrdquo CarbohydratePolymers vol 85 no 1 pp 37ndash43 2011

[71] J Rieger H Freichels A Imberty et al ldquoPolyester nanoparticlespresenting mannose residues toward the development of newvaccine delivery systems combining biodegradability and tar-geting propertiesrdquoBiomacromolecules vol 10 no 3 pp 651ndash6572009

[72] S Kawakami A Sato M Nishikawa F Yamashita and M Ha-shida ldquoMannose receptor-mediated gene transfer into macro-phages using novel mannosylated cationic liposomesrdquo GeneTherapy vol 7 no 4 pp 292ndash299 2000

[73] PMuriel M GMorenoM D C Hernandez E Chavez and LK Alcantar ldquoResolution of liver fibrosis in chronic CCl4administration in the rat after discontinuation of treatmenteffect of silymarin silibinin colchicine and trimethylcolchicinicacidrdquo Basic and Clinical Pharmacology and Toxicology vol 96no 5 pp 375ndash380 2005

[74] J Suojanen S-T Vilen P Nyberg et al ldquoSelective gelatinaseinhibitor peptide is effective in targeting tongue carcinoma celltumors in vivordquo Anticancer Research vol 31 no 11 pp 3659ndash3664 2011

[75] Z Shen W Wei H Tanaka et al ldquoA galactosamine-mediateddrug delivery carrier for targeted liver cancer therapyrdquo Pharma-cological Research vol 64 no 4 pp 410ndash419 2011

[76] L Beljaars K Poelstra GMolema and D K F Meijer ldquoTarget-ing of sugar- and charge-modified albumins to fibrotic rat liversthe accessibility of hepatic cells after chronic bile duct ligationrdquoJournal of Hepatology vol 29 no 4 pp 579ndash588 1998

[77] E A L Biessen D M Beuting H Vietsch M K Bijsterboschand T J C Van Berkel ldquoSpecific targeting of the antiviral drug5-Iodo 2rsquo-deoxyuridine to the parenchymal liver cell using lac-tosylated poly-L-lysinerdquo Journal of Hepatology vol 21 no 5 pp806ndash815 1994

[78] B Schechter L Chen R Arnon andMWilchek ldquoOrgan selec-tive delivery using a tissue-directed sreptavidin-biotin systemtargeting 5-fluorouridine via TNP-streptavidinrdquo Journal ofDrugTargeting vol 6 no 5 pp 337ndash348 1999

[79] L Yuan J Wang and W-C Shen ldquoReversible lipidization ofsomatostatin analogues for the liver targetingrdquo European Jour-nal of Pharmaceutics and Biopharmaceutics vol 70 no 2 pp615ndash620 2008

[80] J-H Han Y-K Oh D-S Kim and C-K Kim ldquoEnhancedhepatocyte uptake and liver targeting ofmethotrexate using gal-actosylated albumin as a carrierrdquo International Journal of Phar-maceutics vol 188 no 1 pp 39ndash47 1999

[81] D-Q Wu B Lu C Chang et al ldquoGalactosylated fluorescentlabeled micelles as a liver targeting drug carrierrdquo Biomaterialsvol 30 no 7 pp 1363ndash1371 2009

[82] J Zhang C Li Z-Y Xue et al ldquoFabrication of lactobionic-load-ed chitosan microcapsules as potential drug carriers targetingthe liverrdquo Acta Biomaterialia vol 7 no 4 pp 1665ndash1673 2011

[83] D Bhadra A K Yadav S Bhadra andN K Jain ldquoGlycodendri-meric nanoparticulate carriers of primaquine phosphate forliver targetingrdquo International Journal of Pharmaceutics vol 295no 1-2 pp 221ndash233 2005

[84] C M Sandrine ldquoTargeting approachesrdquo in Nanotherapeuticspp 67ndash89 Pan Stanford Publishing 2008

[85] R Zhao S Liu S Mao and Y Wang ldquoStudy on liver targetingeffect of vinegar-baked Radix Bupleuri on resveratrol in micerdquoJournal of Ethnopharmacology vol 126 no 3 pp 415ndash420 2009

[86] L Chen B Schechter RArnon andMWilchek ldquoTissue select-ive affinity targeting using the avidin-biotin systemrdquo DrugDevelopment Research vol 50 no 3-4 pp 258ndash271 2000

[87] G Di Stefano C Busi M Derenzini D Trere and L FiumeldquoConjugation of 5-fluoro-21015840-deoxyuridine with lactosaminatedpoly-1-lysine to reduce extrahepatic toxicity in the treatmentof hepatocarcinomasrdquo Italian Journal of Gastroenterology andHepatology vol 30 no 2 pp 173ndash177 1998

[88] V P Torchilin ldquoDrug targetingrdquo European Journal of Pharma-ceutical Sciences vol 11 no 2 pp S81ndashS91 2000

[89] M K Bijsterbosch H Van De Bilt and T J C Van BerkelldquoSpecific targeting of a lipophilic prodrug of iododeoxyuridineto parenchymal liver cells using lactosylated reconstituted highdensity lipoprotein particlesrdquo Biochemical Pharmacology vol52 no 1 pp 113ndash121 1996

[90] A M Dierling and Z Cui ldquoTargeting primaquine into liverusing chylomicron emulsions for potential vivax malaria ther-apyrdquo International Journal of Pharmaceutics vol 303 no 1-2 pp143ndash152 2005

[91] L F Lai andHXGuo ldquoPreparation of new5-fluorouracil-load-ed zein nanoparticles for liver targetingrdquo International Journalof Pharmaceutics vol 404 no 1-2 pp 317ndash323 2011


[92] L Beljaars ldquoAlbumin modified with mannose 6-phosphate apotential carrier for selective delivery of antifibrotic drugs to ratand human hepatic stellate cellsrdquo Hepatology vol 29 no 5 pp1486ndash1493 1999

[93] B Wang W Li K Guo Y Xiao Y Wang and J Fan ldquoMiR-181bPromotes hepatic stellate cells proliferation by targeting p27 andis elevated in the serum of cirrhosis patientsrdquo Biochemical andBiophysical Research Communications vol 421 no 1 pp 4ndash82012

[94] L J Elrick V LeelM G Blaylock et al ldquoGeneration of amono-clonal human single chain antibody fragment to hepatic stellatecellsmdasha potential mechanism for targeting liver anti-fibrotictherapeuticsrdquo Journal of Hepatology vol 42 no 6 pp 888ndash8962005

[95] W Huang W Wang P Wang et al ldquoGlycyrrhetinic acid-mod-ified poly(ethylene glycol)-b-poly(120574-benzyl l-glutamate) mi-celles for liver targeting therapyrdquo Acta Biomaterialia vol 6 no10 pp 3927ndash3935 2010

[96] X Li Q Wu Z Chen X Gong and X Lin ldquoPreparation char-acterization and controlled release of liver-targeting nanoparti-cles from the amphiphilic random copolymerrdquo Polymer vol 49no 22 pp 4769ndash4775 2008

[97] PMa S Liu Y Huang X Chen L Zhang and X Jing ldquoLactosemediated liver-targeting effect observed by ex vivo imagingtechnologyrdquo Biomaterials vol 31 no 9 pp 2646ndash2654 2010

[98] T Gonzalo E G Talman A Van De Ven et al ldquoSelective tar-geting of pentoxifylline to hepatic stellate cells using a novelplatinum-based linker technologyrdquo Journal of Controlled Re-lease vol 111 no 1-2 pp 193ndash203 2006

[99] H-L Jiang J-T Kwon E-M Kim et al ldquoGalactosylated poly-(ethylene glycol)-chitosan-graft-polyethylenimine as a genecarrier for hepatocyte-targetingrdquo Journal of Controlled Releasevol 131 no 2 pp 150ndash157 2008

[100] M Hashida M Nishikawa and Y Takakura ldquoHepatic targetingof drugs and proteins by chemical modificationrdquo Journal ofControlled Release vol 36 no 1-2 pp 99ndash107 1995

[101] Y Xu X Jin Q Ping et al ldquoA novel lipoprotein-mimic nano-carrier composed of the modified protein and lipid for tumorcell targeting deliveryrdquo Journal of Controlled Release vol 146no 3 pp 299ndash308 2010

[102] Y Hu Y Shen B Ji et al ldquoLiver-specific gene therapy of hepat-ocellular carcinoma by targeting human telomerase reversetranscriptase with pegylated immuno-lipopolyplexesrdquo Euro-pean Journal of Pharmaceutics and Biopharmaceutics vol 78no 3 pp 320ndash325 2011

[103] P J Swart T Hirano M E Kuipers et al ldquoTargeting of super-oxide dismutase to the liver results in antiinflammatory effectsin rats with fibrotic liversrdquo Journal of Hepatology vol 31 no 6pp 1034ndash1043 1999

[104] Y Hattori S Kawakami F Yamashita and M Hashida ldquoCon-trolled biodistribution of galactosylated liposomes and incor-porated probucol in hepatocyte-selective drug targetingrdquo Jour-nal of Controlled Release vol 69 no 3 pp 369ndash377 2000

[105] FDanhier BVromanN Lecouturier et al ldquoTargeting of tumorendothelium by RGD-grafted PLGA-nanoparticles loaded withPaclitaxelrdquo Journal of Controlled Release vol 140 no 2 pp 166ndash173 2009

[106] F Li J-Y Sun J-Y Wang et al ldquoEffect of hepatocyte growthfactor encapsulated in targeted liposomes on liver cirrhosisrdquoJournal of Controlled Release vol 131 no 1 pp 77ndash82 2008

[107] G Huang J Diakur Z Xu and L I Wiebe ldquoAsialoglycoproteinreceptor-targeted superparamagnetic iron oxide nanoparticlesrdquo

International Journal of Pharmaceutics vol 360 no 1-2 pp 197ndash203 2008

[108] J H Maeng D-H Lee K H Jung et al ldquoMultifunctionaldoxorubicin loaded superparamagnetic iron oxide nanoparti-cles for chemotherapy and magnetic resonance imaging in livercancerrdquo Biomaterials vol 31 no 18 pp 4995ndash5006 2010

[109] S Becker M Spiess and H-D Klenk ldquoThe asialoglycoproteinreceptor is a potential liver-specific receptor forMarburg virusrdquoJournal of General Virology vol 76 no 2 pp 393ndash399 1995

[110] X-Q Zhang X-LWang P-C Zhang et al ldquoGalactosylated ter-nary DNApolyphosphoramidate nanoparticles mediate highgene transfection efficiency in hepatocytesrdquo Journal of Con-trolled Release vol 102 no 3 pp 749ndash763 2005

[111] M Singh and M Ariatti ldquoTargeted gene delivery into HepG2cells using complexes containing DNA cationized asialooroso-mucoid and activated cationic liposomesrdquo Journal of ControlledRelease vol 92 no 3 pp 383ndash394 2003

[112] T Shinoda A Maeda S Kagatani et al ldquoSpecific interactionbetween galactose branched-cyclodextrins and hepatocytes invitrordquo International Journal of Pharmaceutics vol 167 no 1-2pp 147ndash154 1998

[113] H Harashima and H Kiwada ldquoLiposomal targeting and drugdelivery kinetic considerationrdquo Advanced Drug Delivery Re-views vol 19 no 3 pp 425ndash444 1996

[114] A Lin Y Liu Y Huang et al ldquoGlycyrrhizin surface-modifiedchitosan nanoparticles for hepatocyte-targeted deliveryrdquo Inter-national Journal of Pharmaceutics vol 359 no 1-2 pp 247ndash2532008


[116] S E Gratton P A Ropp P D Pohlhaus et al ldquoThe effect of par-ticle design on cellular internalization pathwaysrdquo Proceedings ofthe National Academy of Sciences of USA vol 105 no 33 pp11613ndash11618 2008

[117] G Sharma D T Valenta Y Altman et al ldquoPolymer particleshape independently influences binding and internalization bymacrophagesrdquo Journal of Controlled Release vol 147 no 3 pp408ndash412 2010

[118] Y Geng P Dalhaimer S Cai et al ldquoShape effects of filamentsversus spherical particles in flow and drug deliveryrdquo NatureNanotechnology vol 2 no 4 pp 249ndash255 2007

[119] S-Y Lin W-H Hsu J-M Lo H-C Tsai and G-H HsiueldquoNovel geometry type of nanocarriers mitigated the phagocy-tosis for drug deliveryrdquo Journal of Controlled Release vol 154no 1 pp 84ndash92 2011

[120] A Arnida M M Janat-Amsbury A Ray C M Peterson andH Ghandehari ldquoGeometry and surface characteristics of goldnanoparticles influence their biodistribution and uptake bymacrophagesrdquo European Journal of Pharmaceutics and Biophar-maceutics vol 77 no 3 pp 417ndash423 2011

[121] P Decuzzi B Godin T Tanaka et al ldquoSize and shape effects inthe biodistribution of intravascularly injected particlesrdquo Journalof Controlled Release vol 141 no 3 pp 320ndash327 2010

[122] N Doshi B Prabhakarpandian A Rea-Ramsey K Pant SSundaram and S Mitragotri ldquoFlow and adhesion of drugcarriers in blood vessels depend on their shape a study usingmodel synthetic microvascular networksrdquo Journal of ControlledRelease vol 146 no 2 pp 196ndash200 2010


[123] Z Liu W Cai L He et al ldquoIn vivo biodistribution and highlyefficient tumour targeting of carbon nanotubes in micerdquoNatureNanotechnology vol 2 no 1 pp 47ndash52 2007

[124] K A Beningo andY-LWang ldquoFc-receptor-mediated phagocy-tosis is regulated bymechanical properties of the targetrdquo Journalof Cell Science vol 115 no 4 pp 849ndash856 2002

[125] C Yamashita H Matsuo K Akiyama and H KiwadaldquoEnhancing effect of cetylmannoside on targeting of liposomesto Kupffer cells in ratsrdquo International Journal of Pharmaceuticsvol 70 no 3 pp 225ndash233 1991

[126] B N Melgert P Olinga J M S Van Der Laan et al ldquoTargetingdexamethasone to Kupffer cells effects on liver inflammationand fibrosis in ratsrdquoHepatology vol 34 no 4 pp 719ndash728 2001

[127] T JMerkel SW Jones K P Herlihy et al ldquoUsingmechanobio-logical mimicry of red blood cells to extend circulation times ofhydrogel microparticlesrdquo Proceedings of the National Academyof Sciences of the United States of America vol 108 no 2 pp586ndash591 2011

[128] HHillaireau and P Couvreur ldquoNanocarriersrsquo entry into the cellrelevance to drug deliveryrdquo Cellular andMolecular Life Sciencesvol 66 no 17 pp 2873ndash2896 2009

[129] D Schuppan M Ruehl R Somasundaram and E G HahnldquoMatrix as a modulator of hepatic fibrogenesisrdquo Seminars inLiver Disease vol 21 no 3 pp 351ndash372 2001

[130] R C Benyon andM J P Arthur ldquoExtracellularmatrix degrada-tion and the role of hepatic stellate cellsrdquo Seminars in Liver Dis-ease vol 21 no 3 pp 373ndash384 2001

[131] D C Rockey ldquoHepatic blood flow regulation by stellate cells innormal and injured liverrdquo Seminars in Liver Disease vol 21 no3 pp 337ndash349 2001

[132] M Luck B R Paulke W Schroder T Blunk and R H Mul-ler ldquoAnalysis of plasma protein adsorption on polymeric nano-particles with different surface characteristicsrdquo Journal of Bio-medical Materials Research vol 39 no 3 pp 478ndash485 1998

[133] R Greupink H I Bakker C Reker-Smit et al ldquoStudies on thetargeted delivery of the antifibrogenic compoundmycophenolicacid to the hepatic stellate cellrdquo Journal of Hepatology vol 43no 5 pp 884ndash892 2005

[134] J E Adrian J A A M Kamps G L Scherphof et al ldquoA novellipid-based drug carrier targeted to the non-parenchymal cellsincluding hepatic stellate cells in the fibrotic livers of bile ductligated ratsrdquo Biochimica et Biophysica Acta vol 1768 no 6 pp1430ndash1439 2007

[135] A Raz C Bucana andW E Fogler ldquoBiochemical morpholog-ical and ultrastructural studies on the uptake of liposomes bymurine macrophagesrdquo Cancer Research vol 41 no 2 pp 487ndash494 1981

[136] A Chonn S C Semple and P R Cullis ldquoAssociation of bloodproteins with large unilamellar liposomes in vivo Relation tocirculation lifetimesrdquo Journal of Biological Chemistry vol 267no 26 pp 18759ndash18765 1992

[137] K Xiao Y Li J Luo et al ldquoThe effect of surface charge onin vivo biodistribution of PEG-oligocholic acid based micellarnanoparticlesrdquo Biomaterials vol 32 no 13 pp 3435ndash3446 2011

[138] AMori A L KlibanovV P Torchilin andLHuang ldquoInfluenceof the steric barrier activity of amphipathic poly(ethyleneglycol)and ganglioside GM1 on the circulation time of liposomesand on the target binding of immunoliposomes in vivordquo FEBSLetters vol 284 no 2 pp 263ndash266 1991

[139] A Gabizon and D Papahadjopoulos ldquoLiposome formulationswith prolonged circulation time in blood and enhanced uptake

by tumorsrdquo Proceedings of the National Academy of Sciences ofthe United States of America vol 85 no 18 pp 6949ndash6953 1988

[140] D Peer andRMargalit ldquoTumor-targeted hyaluronan nanolipo-somes increase the antitumor activity of liposomal doxorubicinin syngeneic and human xenograft mouse tumor modelsrdquoNeoplasia vol 6 no 4 pp 343ndash353 2004

[141] D Liu F Liu and Y K Song ldquoMonosialoganglioside GM1shortens the blood circulation time of liposomes in ratsrdquo Phar-maceutical Research vol 12 no 4 pp 508ndash512 1995

[142] D Liu Y K Song and F Liu ldquoAntibody dependent comple-ment mediated liver uptake of liposomes containing GM1rdquoPharmaceutical Research vol 12 no 11 pp 1775ndash1780 1995

[143] D Liu Q Hu and Y K Song ldquoLiposome clearance from blooddifferent animal species have differentmechanismsrdquoBiochimicaet Biophysica Acta vol 1240 no 2 pp 277ndash284 1995

[144] A Rigotti S L Acton and M Krieger ldquoThe class B scavengerreceptors SR-BI and CD36 are receptors for anionic phospho-lipidsrdquo Journal of Biological Chemistry vol 270 no 27 pp16221ndash16224 1995

[145] Q Yu R Shao H S Qian S E George and D C RockeyldquoGene transfer of the neuronalNO synthase isoform to cirrhoticrat liver ameliorates portal hypertensionrdquo Journal of ClinicalInvestigation vol 105 no 6 pp 741ndash748 2000

[146] Z Qi N Atsuchi A Ooshima A Takeshita and H UenoldquoBlockade of type 120573 transforming growth factor signaling pre-vents liver fibrosis and dysfunction in the ratrdquo Proceedings of theNational Academy of Sciences of theUnited States of America vol96 no 5 pp 2345ndash2349 1999

[147] K L Rudolph S Chang M Millard N Schreiber-Agus and RA DePinho ldquoInhibition of experimental liver cirrhosis in miceby telomerase gene deliveryrdquo Science vol 287 no 5456 pp1253ndash1258 2000

[148] S Salgado J Garcia J Vera et al ldquoLiver cirrhosis is reverted byurokinase-type plasminogen activator gene therapyrdquoMolecularTherapy vol 2 no 6 pp 545ndash551 2000

[149] V Terpstra and T J C Van Berkel ldquoScavenger receptors on liverKupffer cells mediate the in vivo uptake of oxidatively damagedred blood cells in micerdquo Blood vol 95 no 6 pp 2157ndash21632000

[150] C D Oja S C Semple A Chonn and P R Cullis ldquoInfluence ofdose on liposome clearance critical role of blood proteinsrdquoBiochimica et Biophysica Acta vol 1281 no 1 pp 31ndash37 1996

[151] T M Allen and C Hansen ldquoPharmacokinetics of stealth versusconventional liposomes effect of doserdquoBiochimica et BiophysicaActa vol 1068 no 2 pp 133ndash141 1991

[152] Z Panagi A Beletsi G Evangelatos E Livaniou D S Ithak-issios andK Avgoustakis ldquoEffect of dose on the biodistributionand pharmacokinetics of PLGA and PLGA-mPEG nanoparti-clesrdquo International Journal of Pharmaceutics vol 221 no 1-2 pp143ndash152 2001

[153] D D Chow H E Essien M M Padki and K J Hwang ldquoTar-geting small unilamellar liposomes to hepatic parenchymalcells by dose effectrdquo Journal of Pharmacology and ExperimentalTherapeutics vol 248 no 2 pp 506ndash513 1989

[154] EWM Van Etten M T Ten Kate S V Snijders and I A J MBakker-Woudenberg ldquoAdministration of liposomal agents andblood clearance capacity of the mononuclear phagocyte sys-temrdquo Antimicrobial Agents and Chemotherapy vol 42 no 7 pp1677ndash1681 1998

[155] H Harashima K Sakata and H Kiwada ldquoDistinction betweenthe depletion of opsonins and the saturation of uptake in the


dose-dependent hepatic uptake of liposomesrdquo PharmaceuticalResearch vol 10 no 4 pp 606ndash610 1993

[156] A Gabizon D Tzemach L Mak M Bronstein and A THorowitz ldquoDose dependency of pharmacokinetics and thera-peutic efficacy of pegylated liposomal doxorubicin (DOXIL) inmurinemodelsrdquo Journal ofDrugTargeting vol 10 no 7 pp 539ndash548 2002

[157] T L Andresen S S Jensen and K Joslashrgensen ldquoAdvanced strat-egies in liposomal cancer therapy problems and prospects ofactive and tumor specific drug releaserdquo Progress in Lipid Re-search vol 44 no 1 pp 68ndash97 2005

[158] F Chellat Y Merhi A Moreau and L Yahia ldquoTherapeuticpotential of nanoparticulate systems formacrophage targetingrdquoBiomaterials vol 26 no 35 pp 7260ndash7275 2005

[159] P L Williams and H Gray Grayrsquos Anatomy The AnatomicalBasis of Medicine and Surgery Churchill Livingstone 1995

[160] Body Atlas Octopus Books 2008[161] A C Guyton Textbook of Medical Physiology Saunders 1981[162] M Cheng B He T Wan et al ldquo5-Fluorouracil nanoparticles

inhibit hepatocellular carcinoma via activation of the p53 path-way in the orthotopic transplant mouse modelrdquo PLoS One vol7 no 10 article e47115 2012

[163] X LiH Xu XDai Z Zhu B Liu andX Lu ldquoEnhanced in vitroand in vivo therapeutic efficacy of codrug-loaded nanoparticlesagainst liver cancerrdquo International Journal of Nanomedicine vol7 pp 5183ndash5190 2012

[164] X Zhou M Zhang B Yung et al ldquoLactosylated liposomes fortargeted delivery of doxorubicin to hepatocellular carcinomardquoInternational Journal of Nanomedicine vol 7 pp 5465ndash54742012

[165] X Zhang X Zhang P Yu et al ldquoHydrotropic polymeric mixedmicelles based on functional hyperbranched polyglycerolcopolymers as hepatoma-targeting drug delivery systemrdquo Jour-nal of Pharmaceutical Sciences vol 102 no 1 pp 145ndash1453 2013

Submit your manuscripts athttpwwwhindawicom

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014

ToxinsJournal of

VaccinesJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AntibioticsInternational Journal of

ToxicologyJournal of


StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Drug DeliveryJournal of



Advances in Pharmacological Sciences

Tropical MedicineJournal of


Medicinal ChemistryInternational Journal of


AddictionJournal of



BioMed Research International

Emergency Medicine InternationalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Autoimmune Diseases


Anesthesiology Research and Practice

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of


Pharmaceutics


MEDIATORSINFLAMMATION

of


which will recognize and interact with specific cell type ofliver In the present review we enumerate all the methods forattaching targeting moiety to delivery system and differentfactors which could be taken into account while designingNDDS for liver cell which will be of immense importance innear future The review elucidates the importance of deliveryof both the drugs and herbal medications to the liver so as toensure successful treatment outcomes

2 Morphological Study of Liver

Before discussing the different methods of targeting it isnecessary to understand the morphology of liver (especiallyvascular supply) and molecular scale of the target tissue inorder to design a novel drug delivery system rationally

The liver engages numerous metabolic immunologicaland endocrine functions It receives blood (oxygenated anddeoxygenated) from the gut and heart via the portal vein andhepatic artery respectively Blood circulates through a per-meable discontinuous capillary network term as the sinusoidsto reach the central and hepatic veinsThe sinusoids are smallblood vessels (5 to 10120583m wide) between the radiating rowsof hepatocytes having fenestrations of size 100ndash150 nm(depending on the type of animal species)They allow almostunrestricted passage of plasma components to the perisinu-soidal space where the cords of parenchymal cells called ashepatocytes are situated Inside the sinusoid capillaries theKupffer cells are responsible for phagocytic activity of the liver[1 2]

21 Phagocytosis in Kupffer Cells Phagocytosis occurs afterthe multivalent drug delivery system comes in contact withthemacrophagewhere they spread the cellmembrane aroundthe particles to engulf them Macrophages recognize thedelivery systems via the recognition of opsonins present overthem or through interactionwith scavenger receptors presenton Kupffer cells After ingestion phagocytic vesicle (phago-somes) coalesces with intracellular organelles containingdigestive proteins having acidic internal pH to mature intophagolysosomes and to degrade the internal part of the deliv-ery system The delivery system is then eliminated by exo-cytosis after degradation or is sequestered in residual bodieswithin the cell if it cannot be digested [3 4]

22 Macrophages Interaction with the Delivery System Thefollowing factors should be taken into account while dis-cussing the interaction of macrophages with the deliverysystem

Size and Radius The interaction between the macrophagesand delivery system could be influenced by the size and radiusof curvature of delivery system Generally a diameter of1ndash3120583m (in vitro limit is 20120583m) is sufficient for interaction asKupffer cell has ruffled surface Too small particles co-operateless with the cell membrane and gain entry into the cellthrough the other side like pinocytosis or endocytosis whilethe larger particle fails to contact with the cell membrane

Branch of hepaticportal vein

Central vein

Bile duct

Sinusoid

Liver cells

Figure 1 Microscopic view of liver cells

Shape The shape has great impact on the interaction ofdelivery system and macrophages For larger particles elon-gated shapes promote interaction while for smaller particleshape influences the speed of internalization and the differentpathways used to enter the cells Some studies have shownthat in comparison to their spherical shape nonsphericalparticles are steered into distinctive tissue distribution pat-terns by hydrodynamic forces in the bloodstream for exam-ple filomicelles with very high aspect ratios (gt10) and lon-gitudinal lengths around 10 120583m achieve considerably longercirculation times than spherical particles

Flexibility and DeformabilityThese are other parameters thatalso influence the interaction and distribution The flexi-bility of smaller hydrophilic delivery system (approximately200 nm) was found to affect in vitro kinetics and internaliza-tion pathways in macrophages [5] and other nonphagocyticcells [6] In vivo the flexibility and deformability of deliverysystems have great impact on their tissue distribution andretention for example RBC

Surface Properties These properties influence interaction in acomplex manner Positive charges on the surface of deliverysystem have deleterious effect on circulation times whereascontrary findings are reported regarding the impact of neg-ative charge For example He et al [7] studied the effectsof particle size and surface charge on cellular uptakebio-distribution and concluded that in vivo biodistribution ofnanoparticles (NPs) with slight negative charges and particlesize of 150 nm tended to accumulate in tumormore efficientlywhile Funato et al and Nishikawa et al [8 9] reportedthat negatively charged liposomes have a shorter half-life inthe blood Figure 1 provides a microscopic view of the liversurface

3 Essential Attributes for Designing DeliverySystems for Liver Targeting

For a therapeutic moiety to exert its desired effect it needsto be in physical contact with its physiological target such asa receptor present on liver cells Site-specific drug delivery
















amine R M6PIGF II R





Uroplasminogen R




lowastR Receptor



Polymer shell

DrugPolymer core


Polymer

Antibody










Drug Nanospheres


PolymerLigand

Linker

++

+

(a)

Incubation



Micelle

Delivery system

Delivery system

+

(b)


Antibody

Receptor

(c)




(d)






















































[76]



[31 77]



[78]




[79]



[80]






[82]



[63]




[83]


[84]





[86]



[87]









[89]


[90]









[94]



[95]


[96]





[40]



[98]



[99]





[101]



[102]




[104]


Table 3 Continued




[105]




[106 107]




[107]



[108]
















7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of
















amine R M6PIGF II R





Uroplasminogen R




lowastR Receptor



Polymer shell

DrugPolymer core


Polymer

Antibody










Drug Nanospheres


PolymerLigand

Linker

++

+

(a)

Incubation



Micelle

Delivery system

Delivery system

+

(b)


Antibody

Receptor

(c)




(d)






















































[76]



[31 77]



[78]




[79]



[80]






[82]



[63]




[83]


[84]





[86]



[87]









[89]


[90]









[94]



[95]


[96]





[40]



[98]



[99]





[101]



[102]




[104]


Table 3 Continued




[105]




[106 107]




[107]



[108]
















7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of




amine R M6PIGF II R





Uroplasminogen R




lowastR Receptor



Polymer shell

DrugPolymer core


Polymer

Antibody










Drug Nanospheres


PolymerLigand

Linker

++

+

(a)

Incubation



Micelle

Delivery system

Delivery system

+

(b)


Antibody

Receptor

(c)




(d)






















































[76]



[31 77]



[78]




[79]



[80]






[82]



[63]




[83]


[84]





[86]



[87]









[89]


[90]









[94]



[95]


[96]





[40]



[98]



[99]





[101]



[102]




[104]


Table 3 Continued




[105]




[106 107]




[107]



[108]
















7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of


Drug Nanospheres


PolymerLigand

Linker

++

+

(a)

Incubation



Micelle

Delivery system

Delivery system

+

(b)


Antibody

Receptor

(c)




(d)






















































[76]



[31 77]



[78]




[79]



[80]






[82]



[63]




[83]


[84]





[86]



[87]









[89]


[90]









[94]



[95]


[96]





[40]



[98]



[99]





[101]



[102]




[104]


Table 3 Continued




[105]




[106 107]




[107]



[108]
















7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of



















































[76]



[31 77]



[78]




[79]



[80]






[82]



[63]




[83]


[84]





[86]



[87]









[89]


[90]









[94]



[95]


[96]





[40]



[98]



[99]





[101]



[102]




[104]


Table 3 Continued




[105]




[106 107]




[107]



[108]
















7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of







































[76]



[31 77]



[78]




[79]



[80]






[82]



[63]




[83]


[84]





[86]



[87]









[89]


[90]









[94]



[95]


[96]





[40]



[98]



[99]





[101]



[102]




[104]


Table 3 Continued




[105]




[106 107]




[107]



[108]
















7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of



























[76]



[31 77]



[78]




[79]



[80]






[82]



[63]




[83]


[84]





[86]



[87]









[89]


[90]









[94]



[95]


[96]





[40]



[98]



[99]





[101]



[102]




[104]


Table 3 Continued




[105]




[106 107]




[107]



[108]
















7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of

















[76]



[31 77]



[78]




[79]



[80]






[82]



[63]




[83]


[84]





[86]



[87]









[89]


[90]









[94]



[95]


[96]





[40]



[98]



[99]





[101]



[102]




[104]


Table 3 Continued




[105]




[106 107]




[107]



[108]
















7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of






[76]



[31 77]



[78]




[79]



[80]






[82]



[63]




[83]


[84]





[86]



[87]









[89]


[90]









[94]



[95]


[96]





[40]



[98]



[99]





[101]



[102]




[104]


Table 3 Continued




[105]




[106 107]




[107]



[108]
















7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of







[89]


[90]









[94]



[95]


[96]





[40]



[98]



[99]





[101]



[102]




[104]


Table 3 Continued




[105]




[106 107]




[107]



[108]
















7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of


Table 3 Continued




[105]




[106 107]




[107]



[108]
















7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of











7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of



7 Expert Comments








Acknowledgments




References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of



References



















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of





















































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of





















































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of




















































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of



















































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of
















Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of





Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of

Documents

Review Article Efficient Hepatic Delivery of Drugs: Novel ...downloads.hindawi.com/journals/bmri/2013/382184.pdf · Review Article Efficient Hepatic Delivery of Drugs: Novel Strategies