[Myoblast transplantation for heart failure: where are we heading?].
Cell therapy in cardiology is already a reality, as evidenced by the number of ongoing clinical trials. These studies entail administration of either skeletal myoblasts in patients with severe ischemic left ventricular dysfunction or of bone marrow-derived cells in patients with acute myocardial infarction and in whom cell therapy is an adjunct to a percutaneous revascularization procedure. The techniques of preparation, expansion and storage of myoblasts are now quite effective. The problem is simpler for bone marrow cells as in most studies, the procedure is limited to an iliac crest biopsy followed by reinjection of the crude, unfractionated bone marrow, as routinely done in clinical haematology since many years. The results of these studies are not yet fully available. Some of them have been enthusiastically reported to be positive but should be interpreted cautiously because of the usually small sample sizes and the common lack of randomisation and double-blind assessment of outcomes. Thus, the fact that cell therapy has now become a reality should not lead to underscore the yet unsettled fundamental issue, i.e., the ability of this novel mode of therapy to truly regenerate areas of necrotic myocardium and restore function in once akinetic territories. From this standpoint, cell therapy is still a dream. Since the beginning, it has been clear that myoblasts were exclusively committed to differentiate into myotubes, without any evidence for a phenotypic conversion into cardiomyocytes. Although the debate is more controversial for bone marrow cells, the reliance on accurate genetic methods of cell tracking has led to increasingly challenge the purported plasticity of these cells. This by no means implies that cell therapy does not exert beneficial effects that could be mediated by alternate mechanisms like limitation of remodelling of paracrine effects. The basic point is that neither skeletal myoblasts nor bone marrow cells fulfill the major criteria required for a true cardiac regeneration: a coupling of the grafted cells with those of the recipient myocardium and the subsequent generation of a contractile force. It is therefore critical to go on exploring other paths, among which embryonic stem cells are particularly attractive.
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Services de chirurgie cardio-vasculaire et de cardiologie, Hôpital européen Georges Pompidou, Paris. philippe.menasche@hop.egp.ap-hop-paris.fr
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D001854:Bone Marrow Cells; D018929:Cell Culture Techniques; D002986:Clinical Trials as Topic; D006333:Heart Failure / Q000628:therapy*; D006801:Humans; D032446:Myoblasts / Q000637:transplantation*; D009206:Myocardium / Q000166:cytology; D010641:Phenotype; D033581:Stem Cell Transplantation / Q000639:trends*; D016277:Ventricular Function, Left; D020257:Ventricular Remodeling