A new study has identified the process involved in the growth of hair inside nevi, a finding that may help researchers develop new molecular therapies for androgenetic alopecia.
The mouse study, led by the University of California, Irvine, details the essential role played by osteopontin and CD44 molecules in the activation of hair growth inside hairy skin nevi. The researchers note that while nevi accumulate particularly large numbers of senescent pigment cells, robust hair growth still occurs. The study was published in Nature.
“We found that senescent pigment cells produce large quantities of a specific signalling molecule called osteopontin, which causes normally dormant and diminutive hair follicles to activate their stem cells for robust growth of long and thick hairs,” said lead corresponding author Maksim Plikus, University of California, Irvine professor of developmental and cell biology in a press release.
“Senescent cells are typically viewed as detrimental to regeneration and are thought to drive the aging process as they accumulate in tissues throughout the body, but our research clearly shows that cellular senescence has a positive side to it.”
The study used mouse models with pigmented skin spots that had hyperactivated hair stem cells and displayed accelerated hair growth, similar to the clinical observations seen in human hairy skin nevi. The senescent pigment cells, according to the researchers, produced high levels of osteopontin, and hair stem cells had a matching receptor molecule, CD44. Molecular interaction between osteopontin and CD44 activated the hair stem cells, resulting in significant hair growth.
“Our findings provide qualitatively new insights into the relationship between senescent cells and tissue’s own stem cells and reveal positive effects of senescent cells on hair follicle stem cells,” said first author Xiaojie Wang, UCI associate specialist in developmental and cell biology, in the press release.
“As we learn more, that information can potentially be harnessed to develop new therapies that target properties of senescent cells and treat a wide range of regenerative disorders, including common hair loss.”