Development and characterization of a tissue engineered multicomponent skin substitute and a skin model

Eke, Gözde
The tissue engineered human skin substitute has the potential to fill large areas of skin loss caused by severe burns or chronic wounds. It can also serve as an alternative skin model to in vivo testing of drugs or cosmetic products. The aim was to construct a tissue engineered full-thickness human skin model mimicking the native tissue. To this end, this model was developed as epidermis, dermis and subcutaneous tissue of the skin. The feasibility of the dermis layer was tested by co-culturing fibroblasts and epithelial cells isolated from healthy human biopsies in two different scaffolds: An electrospun trilayer mesh and collagen sponge. Dermis substitutes mimicking the native dermis were characterized by scanning electron microscopy, histology, immunohistochemistry and mechanical testing. Decellularized human dermis and native human skin were used as controls. As a subcutaneous tissue, photocrosslinked hydrogels were obtained and loaded with adipose derived stem cells that can be used to improve the regeneration of skin on difficult wound beds by stimulating rapid neovascularization. The photocrosslinkable hydrogels were achieved by first synthesizing methacrylated gelatin and hyaluronic acid. These polymers were then dissolved in media with adipose derived mesenchymal stem cells (ADSCs) and human umbilical vein endothelial cells (HUVEC), and afterward crosslinked to obtain a cell-laden hydrogel. These hydrogels provided a suitable microenvironment for stem cell proliferation, and HUVECs induced prevascularization. Empty and cell-laden gels were used in chick embryo ex ovo to demonstrate the angiogenic activity of the constructs. Penetration of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles was studied in the trilayer electrospun dermal model. Penetration of the particles and release of a lipophilic dye was studied using Rhodamine as a model drug which was released at the epidermal layer and penetrated throughout the construct. In conclusion, skin substitute and model produced in this thesis showed the desired proliferative and angiogenic properties essential to promote vascularization for wound healing and to improve survival of tissue engineered skin substitute. It is also possible to use the tissue engineered skin construct as an in vitro model for drug delivery studies or cosmetic products instead of in vivo animal models.