Mesenchymal stem/stromal cells: a new ''cells as drugs'' paradigm. Efficacy and critical aspects in cell therapy.

Mesenchymal stem cells (MSCs) were first isolated more than 50 years ago from the bone marrow. Currently MSCs may also be isolated from several alternative sources and they have been used in more than a hundred clinical trials worldwide to treat a wide variety of diseases. The MSCs mechanism of action is undefined and currently under investigation.