Decellularized Wharton's jelly matrix as a three dimensional scaffold for wound healing and hair regeneration applications

Abstract

The repair and management of full-thickness skin defects such as those resulting from burns and chronic wounds remains a significant challenge. The shortage of donor sites makes it impractical to treat with autologous skin grafts for defects exceeding 50-60% of the total skin area. Thus, the most promising approach for the repair of full thickness wound is using a tissue-engineered skin graft with the primary goal is to restore lost barrier function. However, regeneration of appendages like hair follicles and sebaceous glands has not yet been achieved. Previously, we have shown that maintaining WJMSCs seeded onto DWJM in osteogenic media induces ectodermal differentiation evident by generating CK 19 positive cells. WJMSCs are easily accessible non-controversial source of MSCs with self-renewal ability and extended proliferation potential, making them excellent candidates for tissue engineering. This dissertation presents a novel method to promote complete skin regeneration. To achieve this, we ectodermally differentiate Wharton’s jelly mesenchymal stem cells (WJMSCs) by seeding these cells onto a three-dimensional decellularized Wharton’s jelly matrix (DWJM) and maintaining them in osteogenic differentiation (OD) media. The combination of WJMSCs, DWJM, an acellular dermal graft (DG) (Alloderm®) and the ectodermally differentiated cells were investigated in a wound healing mouse model. The extraction, characterization and use of DWJM in skin tissue engineering as a bioactive, biocompatible and biodegradable scaffold were demonstrated. WJMSCs cultured on DWJM or DG in both regular and OD media generated cytokeratin19 (CK19), collagen I, and alpha-smooth muscle actin (αSMA) positive cells demonstrating ectodermal differentiation. Further, hair-like structures were generated only when WJMSCs were cultured in OD media on DWJM. We explored the underlying molecular mechanisms for ectodermal differentiation in our model and observed up-regulation of β-catenin, noggin, VCAN, and SMAD genes. Mice with full thickness wounds when transplanted with in vitro differentiated/undifferentiated WJMSCs on DWJM demonstrated no skin regeneration. However, mice transplanted with in vitro differentiated WJMSCs on DG demonstrated complete skin regeneration along with skin appendages like hair follicles and sebaceous glands. Further, the combination of DWJM and DG with in vitro differentiated WJMSCs also showed complete skin regeneration but skin appendages were not as developed. Thus, this current dissertation demonstrates the use of differentiated WJMSCs in combination with DWJM and DG as a novel approach for complete skin regeneration of full thickness wounds in a mouse model.