ABSTRACT
In adults, stem cells are fundamental cell units within every tissue that function as a renewal source of highly specialized, terminally differentiated cells. The cell renewal serves to compensate for the normal cell turnover (cell death) or serves to provide reparative cells for the repair of minor defects. The stem cells can be thought of as the rejuvenation potential of the organism (high during the young or growth phase). Unfortunately, this renewal capacity decreases with age; even amphibians that are able to perfectly regenerate an entire limb lose this capacity with age [1]. Thus, one of the long-term goals of Tissue Engineering is to learn how to control and regulate this natural regeneration potential, so that tissue performance can be enhanced or massive defects can be repaired via an intrinsic regenerative pathway.
