Scientists have identified a cell-signalling pathway in rodents that allows them to regenerate hair follicles and skin while their wounds recover. Researchers from The John Hopkins University in Baltimore, Maryland, who published their findings in Cell Stem Cell, say that this pathway is present in all mammals "presumably including people". This pathway, they suggest, could encourage the growth of new hair, skin and other organ tissue in scarred individuals or burn victims.
The study "uncovers a novel role for a protein that works as a master regulator of regeneration in the skin", says senior study author Luis A Garza, associate professor of dermatology at the John Hopkins University School of Medicine. "Medications that turn on this protein have the powerful potential to decrease scarring as healing of wounds takes place, thereby promoting skin and hair follicle regeneration." The lead author also said that the team conducted their research with the knowledge that damaged skin omits double-stranded RNA – a genetic code that some viruses are known to carry. This RNA is received by a "protein called toll-like receptor 3 (TLR3)" that plays a key role in recognising disease-causing organisms that trigger the immune system into action.
During the healing of wounds, TLR3 also activates genes known as IL6 and STAT3 that promote hair-follicle regeneration. It also activates other molecules that help with hair development, such as Wnt and Shh signalling pathways and a gene called EDAR. Garza explains that the developing embryos have everything they need to make organs and skin in genetic material within the cells, and that advanced knowledge about the pathway may lead to therapies that reactivate them in a bid to help healing.
Garza: "A lot of human disability is from scarring. After a heart attack, we're really good at replacing the blood flow, but it's the scar on the heart afterward that's the real problem. We and others in the field of regenerative medicine are interested in how to enhance or trigger regeneration in such situations. One implication from our work is that all of those different rejuvenation techniques are likely working through dsRNA pathways. It may also be that dsRNA could be directly used to stimulate rejuvenation in aging or hair-follicle growth in burn patients to regain structures that have been lost."
He says that based on their work, pharmaceutical companies have begun work on drugs that activate TLR3, which itself activates the immune system and could be tested to promote regeneration.