Researchers identify cells regulating hair growth, graying

New research identifies hair matrix progenitors charged with regulating hair growth and pigmentation.

“We identified the cells that directly give rise to hair, as well as the mechanism that causes hair to turn gray-findings that could one day help identify possible treatments for balding and hair graying,” says Lu Q. Le, M.D., Ph.D., associate professor of dermatology, University of Texas Southwestern Medical Center in Dallas.

Dr. Le and colleagues found that a protein more commonly linked to nerve development, KROX20, turns into skin cells that become the hair shaft. The hair progenitor cells go on to produce stem cell factor, a protein that is essential for hair pigmentation, according to a UT Southwestern press release.

Deleting the stem cell factor gene in the hair progenitor cells of mice turned the animals’ hair white and deleting the KROX20-producing cells caused baldness.

The researchers made these hair-related findings unexpectedly, while studying the rare genetic disorder Neurofibromatosis Type 1. The resulting study on hair, or lack of it, offers new insight for dermatologists.

Scientists already knew that epithelial stem cells contained in a bulge area of hair follicles are involved in making hair and stem cell factor. But what they didn’t know, in detail, was the identity of the cells that directly give rise to hair. They also didn’t know what happens after those stem cells move down to the base, or bulb, of hair follicles; which cells in the hair follicles produce stem cell factor; or that cells involved in hair shaft creation make the KROX20 protein, according to Dr. Le.

“In baldness, it appears that the epithelial stem cells in the bulge are still there. However, the hair shaft progenitor cells (which differentiated from the epithelial stem cells that are in the bulge) that directly give rise to hair--the KROX20-producing cells--are gone,” Dr. Le says. “This gives us hope that we can figure out a way to activate the differentiation of epithelial stem cells in the bulge into KROX20-producing cells in order to make hair again.”

The researchers will next study whether KROX20 in cells and the stem cell factor gene stop working effectively with aging, resulting in graying, hair thinning and male pattern baldness, according to the release.