inkjet printers print skin

8/7/2019 inkjet printers print skin

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T E C H N I C A L S E M I N A R B Y :

U.SIDDHARTH

SWAYAMBHOO(07B91A04B6)

INKJET PRINTERS INSPIRE

SCIENTISTS TO MAKE SKIN



ABSTRACT

Ink-jet printing technology has inspired scientists to look for ways to buildsheets of skin that could one day be used for grafts in burn victims, experts.

One technique involves a portable bioprinter that could becarried to wounded soldiers on the battlefield where it would scan the injury,take cells from the patient and print a section of compatible skin. Another

uses a three-dimensional printer combining donor cells, biofriendly gel andother materials to build cartilage.

The technology works in part via a scanner that takes ameasure of the affected area and identifies the depth and extent of the injury,informing the bioprinter of how many layers of cells need to be made.



HUMAN SKIN

y Skin is a soft outer covering of an animal, in particular a vertebrate.

y In mammals, the skin is the largest organ of the integumentary system made up of multiple layers of ectodermal tissue, and guards theunderlying muscles, bones, ligaments and internal organs.

y Because it interfaces with the environment, skin plays a key role inprotecting (the body) against pathogens and excessive water loss. Itsother functions are insulation, temperature regulation, sensation, andthe protection of vitamin D folates. Severely damaged skin will try toheal by forming scar tissue. This is often discoloured and depigmented.

y Mammalian skin is composed of two primary layers:

the epidermis, which provides waterproofing and serves as a barrierto infection;

the dermis, which serves as a location for the appendages of skin.



Epidermis: "epi" coming from the Greek meaning "over" or "upon", is

the outermost layer of the skin. It forms the waterproof, protective

wrap over the body's surface and is made up

of stratified squamous epithelium with an underlying basal lamina.

DERMIS : the layer of skin beneath the epidermis that consists

of connective tissue and cushions the body from stress and strain.

The dermis is tightly connected to the epidermis by a basement

membrane.



ARTIFICIAL SKIN

y Artificial skin can refer to skin grown in a laboratory that can beused as skin replacement for people who have suffered skintrauma such as severe burns or skin diseases. Alternatively, it canalso refer to skin synthetically produced for other purposes.

A cross-section through artificial skin (left) compared to section

through human skin (right). Both the natural and the artificial skin are

made up of three layers. Credit: Fraunhofer IGB



SKIN GRAFTS

y Skin grafts were developed as a way to prevent such consequences as wellas to correct deformities. As early as the sixth century B.C. , Ayurvedicsurgeons were involved in nose reconstruction, grafting skin flaps from thepatient's nose. Gaspare Tagliacozzo, an Italian physician, brought thetechnique to Western medicine in the sixteenth century.

y U

ntil the late twentieth century, skin grafts were constructed from thepatient's own skin (autografts) or cadaver skin (allografts). Infection or, inthe case of cadaver skin, rejection were primary concerns. While skingrafted from one part of a patient's body to another is immune to rejection,skin grafts from a donor to a recipient are rejected more aggressively thanany other tissue graft or transplant. Although cadaver skin can provideprotection from infection and loss of fluids during a burn victim's initial

healing period, a subsequent graft of the patient's own skin is oftenrequired. The physician is restricted to what skin the patient has available,a decided disadvantage in the case of severe burn victims.



PRODUCTION PROCESS

LATESTMETHODS

y The technology works in part via a scanner that takes a measure of theaffected area and identifies the depth and extent of the injury, informing

the bioprinter of how many layers of cells need to be made.y First of all, a biopsy ± that is, a sample of human tissue ± is checked for

sterility. A gripper arm then transports the biopsy into the automateddevice where the individual steps are performed: The machine cuts thebiopsy into small pieces, isolates the different cell types, stimulates theirgrowth, and mixes the skin cells with collagen.

y A three-dimensional reconstruction of the different skin layers isproduced with the aid of a special gel matrix ± and the skin is ready. Inthe final step, the machine packages the cells for shipment. Alternatively,the tissue can be cryopreserved ± that is, deep-frozen and stored for lateruse.



CONVENTIONALMETHODS

Raw Materials

y The raw materials needed for the production of artificial skin fall intotwo categories, the biological components and the necessary laboratory equipment. The tissues or samples are taken from the person thatmight be needing the skin graft in the future. These are cultured in thelab in a mixture of cells, gel, collagen. The fibroblasts are stored inglass vials and frozen in liquid nitrogen at -94°F (-70°C). In thecollagen method, keratinocytes are also extracted tested, and frozen.

y If the fibroblasts are to be grown on mesh scaffolding, a polymer iscreated by combining molecules of lactic acid and glycolic acid, thesame elements used to make dissolving sutures. The compoundundergoes a chemical reaction resulting in a larger molecule thatconsists of repeating structural units.



y In the collagen method, a small amount of bovine collagen is extractedfrom the extensor tendon of young calves. The collagen is mixed with anacidic nutrient, and stored in a refrigerator at 39.2°F (4°C).

y Laboratory equipment includes glass vials, tubing, roller bottles, graftingcartridges, molds, and freezers.

y The manufacturing process is deceptively simple. Its main function is totrick the extracted fibroblasts into believing that they are in the humanbody so that they communicate with each other in the natural way tocreate new skin.

Mesh scaffolding method

y 1 F ibroblasts are thawed and expanded. The fibroblasts are transferredfrom the vials into roller bottles, which resemble liter soda bottles. Thebottles are rotated on their sides for three to four weeks. The rollingaction allows the circulation of oxygen, essential to the growth process.



y 2 C ells are transferred to a culture system. The cells are removedfrom the roller bottles, combined with a nutrient-rich media, flowedthrough tubes into thin, cassette-like bioreactors housing thebiodegradable mesh scaffolding, and sterilized with e-beam

radiation. As the cells flow into the cassettes, they adhere to the meshand begin to grow. The cells are flowed back and forth for three tofour weeks. Each day, leftover cell suspension is removed and freshnutrient is added. Oxygen, pH, nutrient flow, and temperature arecontrolled by the culture system. As the new cells create a layer of dermal skin, the polymer disintegrates.

y 3 G rowth cycle completed. When cell growth on the mesh iscompleted, the tissue is rinsed with more nutrient-rich media. A cryoprotectant is added. Cassettes are stored individually, labeled,and frozen.



C ollagen method

y 4 C ells are transferred to a culture system. A small amount of the cold collagen andnutrient media, approximately 12% of the combined solution, is added to thefibroblasts. The mixture is dispensed into molds and allowed to come to roomtemperature. As the collagen warms, it gels, trapping the fibroblasts and generatingthe growth of new skin cells.

y 5 K eratinocytes added. Two weeks after the collagen is added to the fibroblasts, theextracted keratinocytes are thawed and seeded onto the new dermal skin. They areallowed to grow for several days and then exposed to air, inducing the keratinocytesto form epidermal layers.

y 6 G rowth cycle completed. The new skin is stored in sterile containers until needed.

y The medical profession is using artificial skin technology to pioneer organ

reconstruction. It is hoped that this so-called engineered structural tissue will, forexample, someday replace plastic and metal prostheses currently used to replacedamaged joints and bones. Ears and noses will be reconstructed by seeding cartilagecells on polymer mesh. The regeneration of breast and urethral tissues is currently under study in the laboratory. Through this technology, it is possible that one day,livers, kidneys, and even hearts, will be grown from human tissues.



y The medical profession is using artificial skin technology to pioneer organreconstruction. It is hoped that this so-called engineered structural tissuewill, for example, someday replace plastic and metal prostheses currently used to replace damaged joints and bones. Ears and noses will bereconstructed by seeding cartilage cells on polymer mesh. Theregeneration of breast and urethral tissues is currently under study in thelaboratory. Through this technology, it is possible that one day, livers,kidneys, and even hearts, will be grown from human tissues.

y For soldiers in need of skin grafts in battle to heal blasts induced wounds.

y For people that require first aid emergency

y The technique makes it safe, easy and efficient as printing produces thick enough skin that can be placed on the affected area and as the source of the skin is the donor itself there is no problem of rejection and also theskin has correct no: of cells to make it stretchable and grow quickly.

FUTUREAPPLICATIONS



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inkjet printers print skin