Medical Biotechnology Regenerative Medicine Muhammad Adeel Faiza Asghar Amina Shakarullah Topic: Therapuetical Potential and Current Status/Challanges

Applications of Regenerative medicines are both: “Therapeutic” in which tissues are grown invitro or in vivo and then transplanted into patient “Diagnostic” in which tissue is made in vitro and used for testing drug metabolism and uptake, toxicity and pathogenicity.

Advancement in Regenerative medicines are based on: Advancement in “Regenerative medicine” is along two lines of Biomaterial research: to aim at cell/tissue regeneration by means of tissue replenishment,(such as bone marrow transplant) to regenerate tissues using “tissue engineering” techniques

Aim of regenerative medicines: Regenerative medicines are among “next generation technologies” and aim is to improve health and quality of life. These technologies will contribute to reduce medical costs associated with prolonged admission and visits to hospitals and welfare costs associated with nursing care.

Tissue Engineering Products Currently available: Tissue engineering products which are in practical use are in field of: Skin and teeth Bone regeneration Cartilage Cardiovascular system Pancreas and Liver

Components of tissue engineering: Cells Stem (adult, embryonic) Somatic Culture method Signals Differentiation Proliferation Drug delivery system SCAFFOLDS Natural Synthetic vascularization

Current Status of Regenerative medicines: The world wide market size is 17.1 billion yen and reach to 250 billion yen by 2015 Research in tissue engineering has a worldwide demand, as does Japan, which has a rapidly aging population.

Regenerative medicines for skin: Skin is comprised of two component: Epidermis: in which the cells originated in the inner most part move towards outer surface gradually and then fall off. Dermis or inner skin: consist of meticulously woven collagen fibers and elastic fibers protecting lymph and blood vessel and providing tough and elastic texture

Regenerative medicines for skin: The elements of skin can be lost due to: Burn injury bedsores (decubitus). Skin has resilient capacity of regeneration and because of the thin tissue layer, skin rarely has difficulties in culturing.

Full-thickness skin loss Regenerative medicines for skin: Depending on the depth of the layers lost skin damage can be classified as Epidermis loss: it can be cured by grafting cultured skin having only epidermal tissues Full-thickness skin loss in emergency cases temporarily skin cultured from other patients is grafted that is later on replaced with patients own skin culture

Regenerative medicines for skin Decubitus treatment: a porus collagen sponge layer coated with polymers such as silicon on one side is used to regenerate an artificial epidermis, For enhancing the efficacy , the collagen layer is immersed in bone marrow fluid taken from the patient to induce active tissue regeneration.

 Skin autografts are produced by culturing keratinocytes (which may be sorted for p63, the recently described, epidermal stem cell marker) under appropriate conditions not only to generate an epidermal sheet, but also to maintain the stem cell population (holoclones). The epidermal sheet is then placed on top of a dermal substitute comprising devitalized dermis or bioengineered dermal substitutes seeded with dermal fibroblasts. Such two-dimensional composites, generated ex vivo, completely regenerate full-thickness wounds

Challenge in regenerative medicine for skin: Regardless to it that skin regeneration is in a relatively advanced stage both in technique and materials, but currently available artificial skins does not include: skin appendages, such as sweat glands, sebaceous glands and hair follicles. Research and development for regenerating skin containing these appendages and developing suitable scaffold materials is needed. The aesthetic aspect should also be an important consideration for new generation regenerative skins.

 Bone regeneration requires ex vivo expansion of marrow-derived skeletal stem cells and their attachment to three-dimensional scaffolds, such as particles of a hydroxyapatite/tricalcium phosphate ceramic. This composite can be transplanted into segmental defects and will subsequently regenerate an appropriate three-dimensional structure in vivo.

Pancreas and Liver Pancreas: its function has two aspects, as a part of the digestive system secreting pancreatic juice (digestive enzymes), as a part of the endocrine system secreting insulin and other hormones (pancreatic islets) Liver: is involved in energy metabolism and detoxification and other functions that are essential to life.

Pancreas and Liver: Cells in pancreas and liver, have very little extracellular matrix so interaction between the cells plays a more important role in expressing the function of cells. So regeneration of the liver and pancreas as a whole using the currently available technologies is next to impossible, to solve this problem is to regenerate selected minimal functional units and implant them as a whole to effectively substitute the organ.

Pancreas and Liver: To regenerate functional units of these organs,formation of spheroids is attracting attention and most actively under development . A spheroid is a mass of cells that are produced using non adherent round bottom plates and major focus is to produce spheroids while controlling their size and maintaining cell functions.

Tissue engineering of Pancreatic Islets will help to cure Type I diabetes

Pancreas and Liver: Our target is to regenerate the organs with all its original functions and adequate size. So there is need for development of an auxiliary biomaterials that provide a 3- dimensional framework for initial organ development and maintains its structural integrity until the organ can hold its own shape using only the cells and extracellular substrates secreted from them.

The diabetic patient serves as the donor of his own therapeutic tissue. Liver cells are obtained by liver biopsy from diabetic patient, cultured and expanded, transduced with a therputic mix, converted into functioning, insulin-producing beta cells, and then transplanted into a same patient with diabetes. Liver cells are obtained by liver biopsy from diabetic patient, cultured and expanded, transuded with a therapeutic mix converted into functioning, insulin-producing beta cells, and then transplanted into a same patient with diabetes.

Challenges An essential requirement for materials that remain in contact with living tissues for a medium to long period of time is that they are not harmful to tissues and biological activities. The toxicity of substances implanted in the body must be considered differently from those taken orally.

Challenges Thus bioaffinity, or biocompatibility of the material , is the essential element for the development of biomaterials. There still remain many challenges to be solved, such as a significant difference in three-dimensional structure between regenerated and natural tissues/organs.

Challenges: Cells need provision of oxygen and nutrient, and they have to dispose of waste matter. In the environment without vascular system, provision and disposal must depend on liquid phase dispersion, causing cell necrosis in the core of thick cell mass. This problem mostly occur in preparation of large spheroids and culture of osteoblasts in three- dimensional porous media.

Challenges: Culture and multiplication of cells as two-dimensional structures is relatively straight forward, but to develop tissues in three- dimensional shapes retaining cell functions is extremely difficult.