Stem cells and their significancefor the medical practice

摘要

A review on the sources and the different methods forproducing stem cells was made. 'Also the limitations and perspectives fortherapeutic use of the human stem cells were considered. Embryonic stem(ES) cells derived from the inner cell masses (ICM) of blastocysts, fetalprimordial germ cells, stem cells from umbilical cord blood and from adulttissues are a valuable source of cells for regenerative therapy of damaged ordegenerating tissues and even of damaged organs. But there exist immuneresponses associated with the transplantation of the various stem cells, andthus lead to requirement for immunosuppressive drugs and/or immuno-modulatory protocols that carry the risk of serious and potentially life-threatening complications. Also, because of ethical considerations thepractical use of human ES cells produced from normal or nuclear tran-nsferred (NT) embryos is restricted. Three alternatives have been proposed:1) production of ES cells from preimplantation parthenogenetic or androge-netic embryos, homozygous for the genes of major histocompatibilitycomplex (MHC); 2) ES cells from preimplantation embryos produced bynuclear transfer from cells of adult humans in enucleated animal eggs; 3) EScells directly from adult somatic cells without NT. Even in these cases existspotential risk of incorrect expression of many genes, mainly imprinted genes,and this can lead to anomalies or even to cancer in the recipients. It isimportant, therefore, to continue research and to improve the understandingabout the molecular events that take place during nuclear reprogramming, inorder to develop potential new therapies. Especially useful can be the animalmodel systems connected with in vitro culture techniques.