[Stem cells: hype and hope].

There is increasing interest in the use of stem cells for therapeutic purposes. The use of embryonic stem cells carries ethical and legal restrictions that limit their role in tissue regeneration. These restrictions do not apply to somatic stem cells, such as haematopoietic stem cells, which normally reside in the bone marrow. Preclinical studies have produced very promising results using these cells in experimental models of myocardial infarction. Bone-marrow cells have also been used to generate several different types of tissue. However, experimental data suggest that bone marrow also houses other non-haematopoietic stem cells, which could account for the alleged plasticity of haematopoietic stem cells. So far, the results of randomised clinical trials in patients with myocardial infarction or heart failure have been disappointing. It is clear that further research in this field is needed.