Stem Cells, Regeneration, Regenerative Medicine

Abstract

When we think of regeneration we usually imagine the reconstruction of lost body parts. However, this is only one among several regenerative events that organisms perform. Re-generation means generation anew. In this general sense, regeneration occurs at all levels of life, including the level of macromolecules. Proteins suffer irreversible alterations with time (denaturation) and must be replaced by newly synthesized ones. Without renewal, slow loss of function in essential enzymes would eventually result in the death of the cell. Experimental evidence suggests that renewal of the molecular inventory and resulting rejuvenation takes place routinely in the course of cell divisions. Division-mediated rejuvenation confers potential immortality to the single-celled protist. In contrast, terminally differentiated cells, incapable of dividing, will sooner or later die. We will investigate this observation and its cause in Chap. 21. Rejuvenation by mitotic division can be supplemented or replaced by rejuvenation through sexual reproduction.