A new report suggests that stimulating adult stem cells might treat baldness, growing hair on heads that are bare. Previous work has shown that adult stem cells are still present in the hair follicles of the skin of bald men, in the follicle roots, but the stem cells have lost the ability to begin hair regeneration. Hair follicle stem cells need signals from within the skin to grow hair, but the source of those signals has been unclear until now.

Yale researchers used a mouse model to show that hair regeneration requires a type of stem cell, an adipose precursor, that forms new skin fat cells. These stem cells also produce a molecule called PDGF (platelet-derived growth factor) that stimulates other skin stem cells for hair growth. Senior author Valerie Horsley said:

"If we can get these fat cells in the skin to talk to the dormant stem cells at the base of hair follicles, we might be able to get hair to grow again."

The results are published in the journal Cell.