Development of three dimensional human skin equivalents based on decellularized extracellular matrices and tyrosine-derived polycarbonate polymers for in-vitro drug screening applications

Three-dimensional (3D) human skin equivalents (HSEs) are in-vitro models that have morphology and function similar to native human skin. Traditionally, drug discovery for lead compounds rely on conducting efficacy and safety studies through 2D monolayer culture. However, the lack of similarly of 2D monolayer culture to those of in-vivo conditions often leads to failure in later development stages. 3D skin equivalents are more complex in terms of structures and functions. They mirror the environment experienced by the normal cells in the body, reflecting cell-cell interaction, cell-matrix interaction, drug response and thus may be potential tools for drug screening. In this study, development of full-thickness HSEs through novel scaffold materials has been investigated. One approach was to use the top-down approach, in which decellularized matrices obtained and treated from native porcine peritoneal tissues were being investigated as matrix scaffolds to construct HSEs. The second approach was to use the bottom-up approach, where biodegradable tyrosine-derived polymers synthesized at the New Jersey Center of Biomaterials (NJCBM) were electrospun into fibrous porous scaffolds. Scaffold morphological and mechanical properties were analyzed. Decellularized porcine peritoneal matrix was shown to possess similar Young’s Modulus compared to human cadaver skin. Cell-matrix interactions between human dermal cells and various scaffolds were studied using viability assays and fluorescent microscopy imaging. Both decellularized peritoneal matrices and poly(DTE carbonate) scaffolds showed cellular compatibility to human dermal cells. Later, various HSEs models of co-cultured human dermal fibroblasts and human keratinocytes were developed. Differentiated multiple epithelial layers were observed on the models and keratinocyte proliferation markers (i.e., keratin15) and the presence of keratinocyte differentiation markers (i.e., involucrin) were recorded. From the functional aspect, decellularized matrix based-HSEs were able to predict skin irritation in-vitro. The model differentiated non-irritant from irritant compounds based on cell viability and multiple cytokine secretions (i.e., IL-1α, IL-1ra, IL-6, IL-8 and GM-CSF). In conclusion, decellularized extracellular matrices and tyrosine-derived polycarbonate scaffolds are promising matrices for the culture of 3D HSEs constructs. The future development of decellularized extracellular matrix and tyrosine-derived polycarbonate scaffolds-based HSEs will offer more useful applications in drug discovery and drug development in pharmaceutical industries.Ph.D.Includes bibliographical referencesby Pei-Chin Tsa