Researchers at UT Southwestern Medical Center have 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.
“Although this project was started in an effort to understand how certain kinds of tumors form, we ended up learning why hair turns gray and discovering the identity of the cell that directly gives rise to hair,” said Lu Le, MD, PhD, associate professor of dermatology with the Harold C. Simmons Comprehensive Cancer Center at UT Southwestern and one of the authors of study, which was published in Genes and Development (May 2017). “With this knowledge, we hope in the future to create a topical compound or to safely deliver the necessary gene to hair follicles to correct these cosmetic problems.”
While studying Neurofibromatosis Type 1, a rare genetic disease that causes tumors to grow on nerves, the researchers found that a protein called KROX20, more commonly associated with nerve development, turns on in skin cells that become the hair shaft. These hair progenitor cells then produce a protein called stem cell factor (SCF) that the researchers showed is essential for hair pigmentation.
When they deleted the SCF gene in the hair progenitor cells in mouse models, the animal’s hair turned white. When they deleted the KROX20-producing cells, no hair grew and the mice became bald, according to the study.
Dr. Le notes that scientists already knew that stem cells contained in a bulge area of hair follicles are involved in making hair and that SCF is important for pigmented cells. What they did not know in detail is what happens after those stem cells move down to the bulb of the hair follicles, which cells in the hair follicles produce SCF, or that the cells involved in hair shaft creation make the KROX20 protein, he said.
The researchers will now try to find out if the KROX20 in cells and the SCF gene stop working properly as people age, leading to the graying and hair thinning seen in older people.
Image: Lu Le, MD, PhD