Exploring Stem Cells
While not immediately relevant to regenerative medicine, research reported at ScienceDaily provides an interesting new take on stem cells: "it could be the case that at least some of the known adult stem cell types are 'only' the rudiments of earlier embryonal differentiation processes, or even dispersed leftovers from previous evolutionary stages. Indeed, these cells are still showing plasticity which is a characteristic of stem cells, but no direct physiological function can be deduced from it." So the many existing stem cell categories could each be complex, mixed groups of varied function and usefulness - as a rule, when biologists find additional complexity, they're usually on to something. Simplicity in biology is always suspicious.
Link: http://www.sciencedaily.com/releases/2005/11/051102174449.htm