The exact definition of stem cell is sometimes cloudy, but we do know 2 generally accepted criteria: stem cells are able to renew themselves and could differentiate into other type of cells. First, they are unspecialized, mitotic cells that renew themselves for any (i.e. long) periods through series of cell divisions, which result in similar unspecialized stem cells. This is the so called and overstated “immortality” characteristics. The other side of the stem cell coin is that under certain physiologic or experimental conditions (know it’s vague a bit), they can be induced to become differentiated cells with special functions such as the contractile cells of the striatal muscle or the insulin-producing cells of the pancreas. So stem cells are those cells, which give rise to an identical, undifferentiated, mitotic stem cell and a more specialised cell with another phenotype through an asymmetric cell division. The resulting progenitor cells mature into functional, specialised cells of the organism. What kind of cells they could be, is partly the function of the developmental potential of the cells and the local environment, where these cells anchor.
Regenerative medicine is the science and technology built around stem cells’ regenerative capacity. This is a whole new concept compared to the traditional medicine: the aim is to facilitate and amplify or replace the native regenerative potential of the organism, the targeted tissue or organ based on the results of developmental biology and biotechnology. Classical medicine focuses on the patomechanism of the illness, the elimination of cell death, and tissue protection, while regenerative research does not care about the causes of the injury, and its aim is not to eliminate the harmful effects of the injury, but to replace, and renew the damaged function. Here, in the NIH Glossary, you can acquire the basic language of stem cell biology.
Human stem cells in a relative harmony. Nuclei stained with Hoechst (blue), which bind to DNA. Author’s shot.
Coming soon: Why is pimm theoretically and technologically possible? Two arguments.
Originally posted at May 4th, 2006, http://attilachordash.wordpress.com/