Cellular cardiomyoplasty--a novel approach to treat heart disease.

Cell transplantation is a novel experimental strategy to treat heart disease, such as myocardial infarction and heart failure. Its beneficial effects may include active contribution of transplanted cells to contractile function, passive improvement of the mechanics of the heart, induction of neoangiogenesis or other indirect influences on the biology of the heart. Several cell types have been used for cardiac cell transplantation including cardiac cells from fetal or newborn animals and cardiac muscle cell lines, skeletal myoblasts and skeletal muscle cell lines, smooth muscle cells, and a variety of stem cells, either adult or embryonic. With many of these cells, encouraging results in experimental ischemic and nonischemic heart disease have been obtained including successful cell survival after transplantation, integration into the host myocardium, and improvement of the function of diseased hearts. Most of these studies found cardiac contractility improved and some found enhanced angiogenesis. However, the mechanisms of these effects remain obscure, and the impact of dosage (cell number) on functional response is completely unclear. In addition, not enough comparative studies were performed to allow preference of one cell type over the other. The current data suggest that whatever cell species is used, the best survival and integration may be accomplished if immature and undifferentiated cells are used. Any kind of stem cell has obvious advantages in terms of endless reproducibility and plasticity, but the complete differentiation and maturation into cardiac myocytes still needs to be proven. At present several clinical studies are exploring the therapeutic benefits of cellular cardiomyoplasty in patients with ischemic heart disease, but it has to be noted that there are many issues that need to be addressed before this strategy will add to the therapeutic options for patients with heart disease.