Graduate School of Biomedical Sciences | Stem Cell Research and Regenerative Medicine

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Cardiac Stem Cell

(Lay Summary)

Heart disease is a major problem in the United States of America with more than one million succumbing annually. During heart attack, the heart turns on repair mechanisms to compensate for the damage. However, the repair methods used by the heart often can cause more harm than good (Figure 1). Thus, the only known way that a heart muscle can have the permanent damage fixed is by heart transplantation. The method has a low rate of success, compounded by the availability of few donors.

Recent research studies have reported on the existence of cardiac stem cells. These stem cells have been found to develop into heart muscle, blood vessels, and smooth muscle cells to replace the damaged areas of the heart (Figure 2). The research studies in the test tube and in animal studies have found signatures for the cardiac stem cells. They are referred as c-kit, MDR-1 and SCA-1. The cardiac stem cells can have one or combinations of these markers (Table 1).

Enthusiasm about the ability of the cardiac stem cells to restore the damaged heart in animal models has generated a flurry of human clinical trials. Most of these trials are still in phase I therefore they are primarily designed to test the safety of the treatment. One of the problems with these studies is the absence of certain steps with visible discrepancies in the type of donor cells, routes of delivery, associated procedures and onset of disease. Furthermore, absence of control groups, shorter follow-ups and limited number of patients has precluded researchers from a comprehensive picture of the cardiac stem cell.

Although phase I trials did not report on the ability of cardiac stem cell to repair the damaged heart, the studies however presented evidence that this type of cell therapy is safe, and also offers a promising tool to regenerate the myocardium.

Experiments with other stem cells such as embryonic, hematopoietic and mesenchymal stem cells treated with various proteins and or chemicals have provided other ways to get heart muscle cells. However, these cells have certain disadvantages associated with their use in cardiac muscle repair such as ethical issues or the possibility of rejection by the recipient. It is these disadvantages that could be bypassed with future research with cardiac stem cells.

Heart disease continues to be the leading cause of mortality and morbidity in industrialized countries. Current approaches targeting blood flow and ventricular remodeling are discouraging due to the inability for repairing the damaged cardiac muscle. Studies in animal models and human clinical trials have documented the ability of cardiac stem cells to participate in heart regeneration. Researchers have successfully identified cardiac stem cells in the heart, and have also identified their locations within the heart. Current research studies are focused on making the cardiac stem cells expand and survive ex vivo. This would lead to the availability of large quantity of cardiac stem cells for research studies. Animal models and randomized, double-blinded human clinical trials with cardiac stem cells have been, and will be imperative to gather more safe and efficient data that elucidate the underlying mechanism of cardiac regeneration. Through the use of cardiac stem cells in regenerative medicine of the heart, there could be significant improvement in a disease that continues to be a clinical dilemma.

Acknowledgements

This review was prepared by the following graduate students in the Stem Cell Biology Class, Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey: Comfort Amoh-Tonto, Walter Alzate, Nadin Exantus, and Nora Gashi (in alphabetical order).

Teaching Assistant: Raghav G. Murthy

The review was edited by two stem cell biologists.