Stem cells: an alternative to organ transplantation in chronic, degenerative and infectious diseases?

Even in the absence of damage or illness mature animals need billions of new cells every single day of their lives in order to survive and renew circulating blood cells and intestinal and skin lining. This task is accomplished by undifferentiated cells residing in most adult organs. These cells are designated adult stem cells (ASC) since they represent the adult counterpart, present in almost every organ, of the embryonal stem cells (ES) from which the entire human body develops. Scientists first hypothesized the existence of stem cells over a century ago, and haematopoietic stem cells (HSC) have been exploited for the therapy of human diseases for two decades. Other types of stem cells also circulating in the bloodstream have been described. We briefly describe the potential uses of each of these types of cells, including autologous circulating stem cells, for disease therapy and in particular for the possible reversal of liver failure due to chronic hepatitis and/or cirrhosis.