Various stem cell types have been tested for regenerating damaged myocardium after myocardial infarction. However, the results of clinical trials have not been consistent, with only some of the trials reporting small improvements in cardiac function. It seems that engraftment and survival of injected cells is limited and transplanted stem cells either do not differentiate into cardiac cells or differentiate into only limited number of cardiac cells. The exact mechanism(s) of cardiac functional improvement by cell therapy are unclear, but paracrine effect may play a central role. The resident cardiac progenitor cells identified within the adult myocardium have distinct advantages over other stem cell types for cardiac cell therapy, as they are likely precommitted to the cardiovascular fate. However, isolating and expanding these cells from cardiac biopsies is a challenge. More recently, direct reprogramming of fibroblasts into cardiomyocytes has given new hope for myocardial regeneration. Here we will review different stem cells used in cardiac cell therapy with a focus on the native cardiac progenitor cells and briefly outline future directions of cardiac cell therapy.
*Division of Cardiology, Department of Medicine;
†Cardiovascular Research Institute; and
‡Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA.
Reprints: Yerem Yeghiazarians, MD, Division of Cardiology, Department of Medicine, 505 Parnassus Avenue, Box 0103, University of California, San Francisco, San Francisco, CA 94143-0103 (e-mail: firstname.lastname@example.org).
Supported by the UCSF Cardiac Stem Cell Foundation.
The authors report no conflicts of interest.
Received March 12, 2013
Accepted May 01, 2013