These adult stem cells are known as progenitor cells. This means they remain dormant (do nothing) unless they witness some level of tissue injury. It’s the tissue injury that turns them on. So, when a person has a degenerative type problem, the stem cells tend to go to that area of need and stimulate the healing process. We’re still not sure if they simply change into the type of injured tissue needed for repair or if they send out signals that induces the repair by some other mechanism. Suffice it to say that there are multiple animal models and a plethora of human evidence that indicates these are significant reparative cells.
