Re-epithelialization is a key process in wound healing. However, this is insufficient to heal large wounds, such as ulcers and burns, and often skin grafts are employed.
The authors of this paper attempted to convert non-epithelial cells, which would be resident in these large wounds, to keratinocytes as a method of improving wound healing.
Comparison of the transcriptional profile of keratinocytes and dermal fibroblasts revealed 55 transcriptional factors and 31 microRNAs involved in keratinocyte specification. Various combinations were assessed for re-programming by transducing into dermal fibroblasts and monitoring conversion into keratinocytes in vitro. Four key genes were identified: DNP63A, GRHL2, TFAP2A and MYC (DGTM).
Ulcers were created in vivo and isolated using skin chambers to prevent migration of host keratinocytes and wound healing by contraction. Adenoviral delivery of DGTM genes resulted in epithelial-like tissue inside the chamber within 18 days, which resembled the skin adjacent to the wound by 28 days. Once the chamber was removed, the generated tissue then connected with the host tissue whilst maintaining a stratified structure. Further histological analysis revealed the DGTM-skin had intact barrier function, a cornified envelope and normal expression of keratins and loricrin.
Re- epithelialization was also observed when the DGTM-generated skin was wounded for a second time, and DGTM transduction promoted healing of old wounds (7 days post-wounding).
Efficiency of the transduction and conversion into keratinocytes was improved by delivery of the viruses in a collagen gel with FGF2 and a Rock inhibitor, with complete re-epithelialization within 2 – 2.5 weeks.
Although possible clinical applications of these methods are more than likely to be far into the future, they do offer an initial proof of principle for this technique in improving wound healing of skin and potentially other tissues.