Adult Stem Cell Therapy in Perspective

Abstract

Ventricular remodeling and ultimately heart failure are the inexorable consequences of substantial myocardial infarction. In recent years, the understanding that regenerative processes exist at the level of the myocardium has placed stem cell research at center stage in cardiology. Through cellular therapies, the concept of “growing” heart muscle and vascular tissue and manipulating the myocardial cellular environment has revolutionized the approach to treating heart disease. Unfortunately, however, the vast field of possibilities opened by stem cell therapy has frequently given rise to more questions than answers. A few of these questions include: Which patients with cardiovascular diseases should be considered for stem cell therapy? Which type of stem cell(s) should be used? What quantity and concentration of cells should be administered? By what mechanisms do stem cells engraft, survive, and differentiate? Is the functional and morphological cardiac improvement achieved actively (ie, by increasing contractility) or passively (ie, by limiting infarct expansion and remodeling)? What is the lifespan of transplanted stem cells in the heart? How safe is this therapy, and is there potential tumorigenesis of stem cells? What might be the potential benefits of cell transplantation in nonischemic heart failure? In this report, we wish to review available information about cardiovascular stem cell therapy, share our early experience in this new field, and speculate about future directions. Although embryonic stem cells have been shown to have greater potency for proliferation and differentiation than adult stem cells, their lack of availability and ethical issues hamper clinical applications. This report will, therefore, focus on the therapeutic applications of adult stem cells. The diverse literature on stem cell research comprises the work of basic and clinical scientists from many different subspecialties. This may account for the heterogeneous mixture of models, methods, types, quantity, and nature of the cells employed and the timing of …