Research published in the January 2011 issue of the Journal of Clinical Investigation (Vol. 121, issue 1) reveals another breakthrough in the medical community’s understanding of the causes of — and possible cure for — androgenetic alopecia, or common male pattern baldness. The new research shows that the presence of a certain type of cell, called progenitor cells, is significantly reduced in men with common baldness compared to men who are not bald.
An article on AOL, which calls these “faulty” stem cells the root of hair loss in men, sheds light on the findings:
Using cell samples from men having hair transplants, a team led by University of Pennsylvania dermatologist Dr. George Cotsarelis compared follicles from portions of bald scalp to follicles from scalp areas with hair.
They learned that on the same person, the bald patches had an equal number of stem cells as the patches with hair. But they did find a difference: the areas of bald scalp had a significantly lower number of a more mature type of cell, called a progenitor cell.
That finding suggests that stem cells in parts of the head without hair have malfunctioned, losing their ability to convert into progenitor cells. ((AOL, “Scientists Trace Root of Male Hair Loss to Faulty Stem Cells,” January 5th 2011))
The study showed that, contrary to conventional wisdom, it is not the total “number” of stem cells that causes hair loss. In fact, the scientists’ original hypothesis was that, “the miniaturization of the hair follicle seen in [androgenetic alopecia] may result from loss of hair follicle stem cells.” That hypothesis turned out to be inaccurate. Instead, the authors of the study indicate that the findings:
…Support the notion that a defect in conversion of hair follicle stem cells to progenitor cells plays a role in the pathogenesis of [androgenetic alopecia]. ((J Clin Invest. doi:10.1172/JCI44478.))
The study’s results suggest that further research into the mechanism for the conversion of hair follicle stem cells to progenitor cells is warranted. If scientists can devise a way to correct that mechanism, then, in theory, stem cells in men who are predisposed to have androgenetic alopecia can be converted to progenitor cells at a normal rate. That correction would, in theory, eliminate that person’s susceptibility to the hair follicle miniaturization which causes hair loss, and would effectively cure his male pattern baldness.
Compared to stem cells, progenitor cells are further along in the process of differentiating into their target tissue, in this case mature hair follicles. Whereas stem cells are pluripotent, meaning that they can differentiate into a number of types of cells, progenitor cells are already committed to a specific cell line. Another important difference between stem cells and progenitor cells is that stem cells can replicate indefinitely, whereas progenitor cells can only divide a limited number of times.
For further reading on this stem cells and the causes of hair loss, here are some links:
- Posts tagged “Stem Cells” on the Hair Transplant Blog
- Read about causes of hair loss in men for a discussion on miniaturization and how it causes hair loss
- Article on the use of stem cells to treat hair loss
- The study publication in the Journal of Clinical Investigation
- Discussion of progenitor cells and stem cells on wikipedia