FLICKR, MARINA DEL CASTELLAs people age, hair follicle stem cells in the scalp accumulate mutations and the follicles themselves shrink, according to a study published last week (February 4) in Science. Analyzing scalp skin samples from women aged 22 to 70, Hiroyuki Matsumura of the Tokyo Medical and Dental University and colleagues found older women’s cells had more mutations and their follicles were smaller than younger women’s, on average. The researchers identified type XVII collagen (COL17A1) as a key player in hair thinning; DNA damage that depleted COL17A1 led to cellular shedding and follicular shrinkage, whereas mice engineered to produced extra COL17A1 did not experience follicle shrinkage or lose as much hair as wild-type mice.
Meanwhile, a team at the University of Colorado found that hair follicle stem cells go dormant, but that deleting the gene for the Foxc1 protein can avoid such dormancy. “We discovered that these cells ‘know’ when to stop,” said coauthor Rui Yi told STAT News. “If we can interfere with that factor, or take that factor away from the stem cell, we can shorten the dormant stage and instead induce the cells to continue dividing and stimulate hair growth.” Yi and colleagues published their results in Science last week (February 7).