Most people notice that as their body ages, it tends not to function as well as it used to. Conditions like osteoarthritis begin to appear, old injuries can be a continuing source of discomfort and recovering from new injuries frequently is slow and incomplete. Part of the reason for this less-than-optimal functionality is that the body does not produce as many stem cells as it did when it was young. The body contains some 200 different kinds of cells. Many of these are assigned a specific purpose in the body. Others, like stem cells, can take on any identity that the [...]