Wound closure rates in human organotypic skin models are increased by connexin mimetic peptides

Recent studies suggest significant increases in skin wound healing rates occur by altering gap junction intercellular communication. Connexin mimetic peptides, which directly target specific connexins (Cx), have great therapeutic potential. Thus we analysed their effect on cell migration responses during wound closure in an organotypic human skin model.
Primary skin fibroblasts and keratinocytes were derived from child foreskins obtained with ethical approval and patient consent. Keratinocytes were seeded onto Transwell inserts following culture of dermal fibroblasts on their undersides. Cells were cultured to confluence, and then exposed to the air-liquid interface forming organotypic living skin equivalents. Immunocytochemistry determined connexin and differentiation marker expression profiles. Cells were treated with connexin mimetic peptides targeted to Cx43 to block gap junction functionality: non-connexin specific Gap26M, and Cx43-specific Gap27. Following scrape wounding through the ‘epidermal layer’, migration studies compared rates of wound closure over 78 hours with and without peptide treatment, which was replaced every 12 hours.
Keratinocytes stratified in the model, expressing Cx43 in basal proliferating cells and patchy Cx26 predominantly in upper layers with limited co-localisation with Cx43. A range of differentiation markers, including loricrin and involucrin were expressed, confirming profiles seen in vivo. Gap26M and Gap27 (100 µM each) significantly increased wound closure rates (P < 0.01), with Gap27 closing wounds faster than Gap26M.
Connexin mimetic peptides increased wound closure rates in this human organotypic skin model, which was shown to be representative of human skin. Connexin mimetic peptides can directly improve wound closure and have therapeutic potential in wound healing.