Chimeric composite skin substitutes for delivery of autologous keratinocytes to promote tissue regeneration.

OBJECTIVE We hypothesize that the pathogen-free NIKS human keratinocyte progenitor cell line cultured in a chimeric fashion with patient's primary keratinocytes would produce a fully stratified engineered skin substitute tissue and serve to deliver autologous keratinocytes to a cutaneous wound. SUMMARY OF BACKGROUND DATA Chimeric autologous/allogeneic bioengineered skin substitutes offer an innovative regenerative medicine approach for providing wound coverage and restoring cutaneous barrier function while delivering autologous keratinocytes to the wound site. NIKS keratinocytes are an attractive allogeneic cell source for this application. METHODS Mixed populations of green fluorescent protein (GFP)-labeled NIKS and unlabeled primary keratinocytes were used to model the allogeneic and autologous components in chimeric monolayer and organotypic cultures. RESULTS In monolayer coculture, GFP-labeled NIKS had no effect on the growth rate of primary keratinocytes and cell-cell junction formation between labeled and unlabeled keratinocytes was observed. In organotypic culture employing dermal and epidermal compartments, chimeric composite skin substitutes generated using up to 90% GFP-labeled NIKS exhibited normal tissue architecture and possessed substantial regions attributable to the primary keratinocytes. Tissues expressed proteins essential for the structure and function of a contiguous, fully-stratified squamous epithelia and exhibited barrier function similar to that of native skin. Furthermore, chimeric human skin substitutes stably engrafted in an in vivo mouse model, with long-term retention of primary keratinocytes but loss of the GFP-labeled NIKS population by 28 days after surgical application. CONCLUSIONS This study provides proof of concept for the use of NIKS keratinocytes as an allogeneic cell source for the formation of bioengineered chimeric skin substitute tissues, providing immediate formal wound coverage while simultaneously supplying autologous cells for tissue regeneration.