[Stem cell therapy and heart failure: hopes and disappointments].

Despite therapeutic advances, heart failure remains a common and serious event characterized by initial and progressive loss of cardiac myocytes, a loss that is currently untreatable. Cell therapy has emerged as a promising new approach to the treatment of heart failure, with very encouraging experimental results. Since 2000, when human stem cell therapy was first attempted in France, clinical trials with adult stem cells (myoblasts, bone-marrow derived cells, mesenchymal stem cells) have given variable results. The inconsistent and modest therapeutic benefit observed in these studies is due more to paracrine effects than to the hoped-for cell replacement, as adult stem cells do not turn into cardiomyocytes and their survival rate after transplantation is very low. In order to be effective, cell therapy should use heart muscle cells derived from pluri- or multipotent cells (human embryonic stem cells, induced pluripotent stem cells, resident cardiac cells), which are likely to have a higher survival rate in a hostile biological environment and deteriorated tissue scaffold. Cardiac tissue engineering assisted by nanotechnologies may eventually help to meet this challenge.