Unravelling the wound healing efficiency of 3D bioprinted alginate-gelatin-diethylaminoethyl cellulose-fibrinogen based skin construct in a rat's full thickness wound model.

The skin, being the largest external organ, is highly vulnerable to injuries. To address the donor skin scarcity, tissue engineering and regenerative medicine have emerged as an alternative strategies to skin grafting over the past few decades. Recent advancements in 3D bioprinting technology however, have positioned it as a promising tool for constructing tissue that closely mimics in-vivo conditions, using a variety of biomaterials to meet the demands of tissue repair. An ideal 3D-printed tissue construct has the potential to provide an ideal tissue microenvironment, promoting wound healing while minimizing scar formation. In this study, we first optimized the bioink formulation by conducting toxicological evaluations, including skin irritation and skin sensitization tests, on two formulations of alginate-gelatin-DEAE cellulose, with and without fibrinogen. The addition of fibrinogen was found to reduce inflammation, making the fibrinogen-containing formulation the preferred choice for further studies. Further, we have analyzed the wound healing efficiency of 3D-printed dermal and epidermal-dermal constructs in rat full thickness wound model. Skin cells were isolated from rat tissue, and dermal, epidermal skin constructs were printed layer by layer using an alginate-gelatin-DEAE cellulose and fibrinogen-based bioink formulation, previously optimized in our laboratory. Full thickness excision wound was created and acellular, dermal and epidermal-dermal construct were implanted. Wound healing was analyzed by means of wound contraction, collagen synthesis, histopathological evaluation and gene expression analysis. Our results indicate that the epidermal-dermal construct promotes faster wound healing and enhanced angiogenesis compared to the dermal-alone and acellular constructs.