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Delivery Systems. Scaffolds, Growth Factors, and Tissue Constructs. Hasan Uludag Department of Chemical & Materials Engineering, Department of Biomedical Engineering, and Faculty of Pharmacy & Pharmaceutical Sciences, University of Alberta, Edmonton, AB. Bone Healing : - PowerPoint PPT Presentation
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Scaffolds, Growth Factors, and Tissue Constructs
Hasan Uludag
Department of Chemical & Materials Engineering,
Department of Biomedical Engineering, and
Faculty of Pharmacy & Pharmaceutical Sciences,
University of Alberta, Edmonton, AB
Delivery Systems
Bone Healing:an orchestrated process of molecular and cellular events
Hematoma
Angiogenesis
Influx of Stem Cells
Osteogenic Differentiation
Bone Deposition
Remodelling
• chemotaxis, proliferation, differentiation, osteogenesis, and apoptosis• all processes regulated by growth factors and the extracellular matrix
Shier D. et al., Hole's Human Anatomy & Physiology, 1996.
Approaches for Bone Regeneration:
• Extracellular Matrices: dynamic scaffolding capable of modulating cell activity: natural (collagen) or synthetic (apatite fillers)
• Growth Factors: endogenous regulators of cellular activity: chemotaxis, proliferation, and differentiation (BMPs)
• Osteogenic Cells: cells that can differentiate under the influence of local factors (bone marrow cells or engineered cells)
A Brief History of BMP Development
• 1965 ~ Description of bone morphogenetic activity from demineralized bone matrix(M. Urist, Science)
• 1988 ~ Cloning of recombinant human BMP-2 and reproduction of BMP activity by a single protein (Wozney et al., Science)
• 1988-2000 ~ Development of a delivery system
• >2000 ~ Regulatory approval, publications on specific clinical indications, success rates, and alternatives.
TORONTO
BOSTON
GENETICS INSTITUTE INC.
Osteoinductive Devices in Clinics
BMP-2 Soaked Collagen Sponge Wet Sponge in Fusion Cage
Demineralized Bone Powder to be Soaked with OP-1 (BMP-7)
Representation of an Osteoinductive Device
cell flux
cell flux
cell flux
BMP release
biomaterialscaffold
Effect of biomaterial scaffold on BMP release kinetics from implants
release kinetics ≈ 'retention'
Subsequent Pharmacokinetics
0 20 40 60 80
%Implanted Dose
Dexon
deLip-Bovine Bone
Synhetic HA
TCP
bovine Mineral
human Mineral
coral HA
rat DBM
human DBM
Gelatin Sponge
Collagen Sponge (2)
Collagen Sponge (1)
Initial (3 hr) Recovery of 125I-BMP-2 in Rat Ectopic Model
Retention of different BMPs in implants
0.01
0.1
1
10
100
0 5 10 15
Succ. rhBMP-2
Acet. rhBMP-2
rhBMP-2 (E.coli)
rhBMP-6
rhBMP-4
rhBMP-2
0.01
0.1
1
10
100
0 5 10 15
Collagen Sponge Poly(glycolic acid)
Time (days)
Per
cen
t R
eten
tio
n
Relationship between BMP retention and osteoinductive activity in implants
Strategy-1Biomaterial-1
Biomaterial-2BMP-X
Strategy-2 Biomaterial
BMP-Y
BMP-Z
BMP-2 vs. BMP-4: Comparison of protein retention and bone formation in the rat ectopic model
Pharmacokinetics Osteoinduction
O
NH
NiPAM(N-isopropylacrylamide)
O
OR
Alkyl-methacrylates
O
ON
O
O
NASI(N-acryloxysuccinimide)
Engineered biomaterials for increased retention of BMPs after injection
NiPAM/EMA-49 kD
NiPAM/EMA/NASI-50 kD
NiPAM/EMA-404 kD
NiPAM/EMA/NASI-422 kD
Temperature-Sensitive Polymers
BMP-biomaterial interactions
BMPs
BMP-2 Retention by NiPAM-Polymers (intramuscular injection model in rats)
Time (days)
% R
eten
tio
n
0.1
1
10
100
0 7 14
BMA/NASI (15.6 oC)
BMA (14.8 oC)
BMA/NASI (24.7 oC)
BMA (25.6 oC)
BMP-2 alone
An Osteoinductive Device by Gene Delivery
cell flux
cell flux
cell flux
release of osteoinductive (BMP-2) genes
biomaterialscaffold
... Lieberman et al. (UCLA) 1998.
... Huard et al. (U. Pittsburg) 1999.
... Helm et al. (U. Virginia) 1999.
MedicinalAgent
MedicinalAgent
Growth Factors for Systemic Bone Therapy
BP conjugation as a means to impart boneaffinity (Zhang et al., Chem. Soc. Rev. 2006)
BisphosphonatesQuickTime™ and a
TIFF (LZW) decompressorare needed to see this picture.
Protein
Protein chemistry to couple bisphosphonates therapeutic proteins
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
sulfoSMCC
aminoBP ( )
O
O
N
O
ONaO3S
NO
O
sulfoSMCC
Protein
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
MedicinalAgent
New bisphosphonates engineered specifically for targeting proteins to bone
MedicinalAgent
(Bansal et al., J. Pharm. Sci. 2004; Bansal et al., Angew Chem. 2005)
Di-Bisphosphonate Tetra-Bisphosphonate
Effectiveness of BP-coupled proteins to seek bone after systemic administration ?
Targeting Efficiency:Bone Delivery of BP-Conjugate
Bone Delivery of Native Protein
MedicinalAgent
(Zhang et al., Chem. Soc. Rev. 2006)
3-6 Hours 1 Day 2-4 Days
Protein Linker Substitution Route Tibia Femur Tibia Femur Tibia Femur
BSA-aBP SMCC 11.0 IV 2.2 2.0 3.7 3.7
BSA-aBP* SMCC 11.0 IV 2.2 3.0 7.5 5.9
BSA-aBP SMCC 11.0 SC 2.5 1.9
LYZ-aBP SMCC 3.9 IV 4.1 5.3 5.6 3.7
LYZ-aBP SMCC 3.9 SC 3.1 4.5
Fetuin-aBP SMCC 6.1 IV 0.9 1.0 0.9 0.6 0.6 0.8
Fetuin-aBP SMCC 6.1 IP 0.7 0.6
Fetuin-aBP MMCCH 7.1 IV 1.0 1.0
Fetuin-diBP EDC/NHS 1.2 IV 1.8 2.1
BSA-diBP EDC/NHS 2.6 IV 3.7 2.9
BSA-tetraBP EDC/NHS 3.6 IV 4.1 4.7
BSA-tetraBP EDC/NHS 3.6 IP 3.4 3.7
IgG-diBP EDC/NHS 6.3 IV 2.6 1.5
BMP-2-aBP SMCC ~3 IV 2.8 4.3
ACKNOWLEDGEMENTS
Co-workers and Collaborators
S. Gittens G. Bansal
T.J. Gao G. Wohl
S. Zhang T. Haque
A. Jalil J. Yang
C. Kucharski J.E.I. Wright
J. Wozney (Genetics Institute)
W. Sebald (U. of Würzburg)
R.F. Zernicke, J.R. Matyas (UC)A. Lavasanifar (UA)
Financial SupportCanadian Institutes of Health Research, AHFMR/CFI,Genetics Institute Inc., Millenium Biologics, Whitaker Foundation, NSERC