Retinoic acid, the active state of Vitamin A, appears to regulate how stem cells enter and exit a transient state central to their role in wound repair.
When a child falls off her bike and scrapes her knee, skin stem cells rush to the rescue, growing new epidermis to cover the wound. But only some of the stem cells that will ultimately patch her up are normally dedicated to replenishing the epidermis that protects her body. Others are former hair follicle stem cells, which usually promote hair growth but respond to the more urgent needs of the moment, morphing into epidermal stem cells to bolster local ranks and repair efforts. To do that, these hair follicle stem cells first enter a pliable state in which they temporarily express the transcription factors of both types of stem cells, hair and epidermis.
Now, new research demonstrates that once stem cells have entered this state,…
