Isotonic medium treatment limits burn wound microbial colonisation and improves tissue repair.

Burn injuries undergo a complex healing process in which progressive spreading of epithelial damage can lead to secondary complications such as wound infection, which is a major driver of mortality among burn patients. We recently reported that burning larval zebrafish triggers dysregulated keratinocyte dynamics compared to mechanical injury. Here, we investigate keratinocyte behaviour following burn injury and the subsequent potential for microbial colonisation of burn wounds over time. Real-time imaging, coupled with tracking of photoconverted cells, revealed that early keratinocyte motility contributes to the spread of epithelial damage beyond the initial site of burn injury and that increased epithelial damage was associated with wound colonisation by the fungal pathogen Candida albicans. Modulating osmotic balance by treating larval zebrafish with isotonic medium limited the spread of epithelial damage and reduced microbial colonisation of burn wounds. Using cultured human skin, we found that topical treatment with isotonic solution (saline) similarly prevented the spread of epithelial damage over time. These findings indicate that keratinocyte behaviour contributes to burn wound progression in larval zebrafish and links keratinocyte dynamics to microbial colonisation of burn wounded tissue.