Stem cells and diabetes

Diabetes mellitus is a metabolic disorder affecting 2-5% of the population. Transplantation of isolated islets of Langerhans from donor pancreata coul d be a cure for diabetes; however, such an approach is limited by the scarc ity of the transplantation material and the long-term side effects of immun osuppressive therapy. These problems may be overcome by using a renewable s ource of cells, such as islet cells derived from stem cells. Stem cells are defined as clonogenic cells capable of both self-renewal and multilineage differentiation. This mean that these cells can be expanded in vivo or in v itro and differentiated to produce the desired cell type. There exist sever al sources of stem cells that have been demonstrated to give rise to plurip otent cell lines: 1) embryonic stem cells; 2) embryonic germ cells; 3) embr yonic carcinoma cells; and 4) adult stem cells. By using in vitro different iation and selection protocols, embryonic stem cells can be guided into spe cific cell lineages and selected by applying genetic selection when a marke r gene is expressed. Recently, differentiation and cell selection protocols have been used to generate embryonic stem cell-derived insulin-secreting c ells that normalise blood glucose when transplanted into diabetic animals. Some recent reports suggest that functional plasticity of adult stem cells may be greater than expected. The use of adult stem cells will circumvent t he ethical dilemma surrounding embryonic stem cells and will allow autotran splantation. These investigations have increased the expectations that cell therapy could be one of the solutions to diabetes. (C) 2001 Editions scien tifiques et medicales Elsevier SAS.