Question: how does the cemical siganal wake the stem cells?

James Chan answered on 16 Mar 2011:

Haha, lots of people have asked me that. Let me explain it like this. I work with adult stem cells, so these are stem cells that can be found in all the different organs in your body. I usually extract them from the muscles and bones of people who have been run over by a car and need an operation – don’t worry, I take them from the bits that were going to go in the bin anyway!!
So, these stem cells usually don’t do much in a healthy person. But when an injury happens, then they are recruited to the injury site to heal the wound. How does this happen? Well, when you get an injury, like a cut or something, your white blood cells detect this damage and start releasing thousands of different chemicals. Many of these recruit other white cells, and others ‘wake up’ the stem cells. So these stem cells, which otherwise would just be sitting there, can either start dividing and making more of themselves, or start moving towards the injury site, and maybe even turn into a different cell type. In my research, we have found a chemical that causes the stem cells to move to the broken parts of the bone and once they get there, they turn into bone cells to help with the healing. It’s pretty clever. Check out the link on my profile and you’ll see some cool animation of how this happens.
Hope this explains your question!