Most wounds clear up by themselves, but some fail to heal and become chronic. An international team of researchers led from Karolinska Institutet, now unveil the important role of so-called microRNAs in regulating skin wound healing, pointing to new therapeutic possibilities for the treatment of hard-to-heal wounds. Chronic wounds affect 0.2-1 percent of the population in developed countries and represent an increasing health problem and an economic burden to society. Current treatments focus on optimising controllable factors such as clearing infections. There is a major medical need for treatments that have a direct impact on the wound healing process, and this is why the researchers set out to find therapeutic targets for chronic skin wounds.

Wound healing is a complex process that can be divided into several phases -- two of these are the inflammatory and the proliferative phase. During the inflammatory phase, damaged and dead cells, bacteria, and debris are cleared out by immune cells. Next is the proliferative phase, where skin cells multiply and there is growth of new tissue. The transition between these two phases is a critical regulatory point that can determine the outcome of the healing process. Hence, the researchers decided to look for factors that mediate this transition.

MicroRNAs, or miRNAs, are short pieces of genetic code that, instead of coding for proteins, regulate the expression of genes. Since the discovery of miRNAs in 1993, many studies have shown that miRNAs are involved in a range of diseases. 

"There is very little known about the expression and function of miRNAs in human skin wounds, but we have previously shown that miRNAs play important roles in the regulation of the cells in the outermost layer of the skin, also called keratinocytes", says Dr. Ning Xu Landén, principal investigator at the department of medicine, Solna, Karolinska Institutet.