MicroRNAs involved in human skin burns, wound healing and scarring

MicroRNAs are small, non-coding RNAs that regulate gene expression, and consequently protein synthesis. Downregulation and upregulation of miRNAs and their corresponding genes can alter cell apoptosis, proliferation, migration and fibroproliferative responses following a thermal injury. This review summarises the evidence for altered human miRNA expression post-burn, and during wound healing and scarring. In addition, the most relevant miRNA targets and their roles in potential pathways are described. Previous studies using molecular techniques have identified 197 miRNAs associated with human wound healing, burn wound healing and scarring. Five miRNAs alter the expression of fibroproliferative markers, proliferation and migration of fibroblasts and keratinocytes post-burn: hsa-miR-21 and hsa-miR-31 are increased after wounding, and hsa-miR-23b, hsa-miR-200b and hsa-let-7c are decreased. Four of these five miRNAs are associated with the TGF-beta pathway. In the future, large scale, in vivo, longitudinal human studies utilising a range of cell types, ethnicity and clinical healing outcomes are fundamental to identify burn wound healing and scarring specific markers. A comprehensive understanding of the underlying pathways will facilitate the development of clinical diagnostic or prognostic tools for better scar management and the identification of novel treatment targets for improved healing outcomes in burn patients.