[Adult neurogenesis and stem cells. Functional capacity].

The ability of stem cells to give rise to new neurons in the adult central nervous system is a phenomenon that has raised many hopes. The possible doors opened by the potentiality of these cells in benefit of neurological patients are numerous. But we need more research and facts to avoid raising false expectations. There is no sound scientific proof to sustain the excitement created by embryonic stem cell therapy. In general, because this therapy is still a distant goal; in particular because the widespread degenerative processes underlying Parkinson's and Alzheimer's diseases make complete repair through transplant practically impossible. It is also hard to understand why research in human embryonic stem cells is being promoted when there are no previous sound results using animal embryonic stem cells. In addition, there are existing alternatives to embryonic stem cells, without ethical problems, that can obtain cells to restore damaged adult tissues, using more promising techniques with already contrasted results.