How to evaluate efficacy of stem cell therapy: The role of current imaging modalities

Left ventricular dysfunction and adverse remodeling due to myocardial ischemia is one of the common manifestations in chronic coronary artery disease. Timely restoration of blood flow can reduce infarct size, but ischemic regions of myocardium remain in up to two-thirds of patients due to microvascular obstruction. Ischemic left ventricular dusfunction and remodeling with viable or partially viable myocardium may have better outcomes when receive appropriate therapy. One of the novel therapeutic strategies to reduce or probably prevent adverse remodeling is stem cell-based therapy. Ability to measure and visualize cardiac remodeling at cellular level may be extremely useful for clinicians and shifts paradigm of treating cardiovascular diseases. Due to the technical limitations of the “in vivo” visualization of transplanted stem cells, the therapeutic mechanisms and biosafety of stem cells are poorly defined, which limits the speed of clinical translation. We hypothesize that evaluation of viability might give insights into a state of myocardium at cellular or molecular level. Viability simply refers to a cell that is not irreversible damaged and may indicate a myocardial substrate that can improve in response to a range of interventions. The goal of viability testing as a surrogate is to identify amount of viable myocardium that would provide reverse remodeling , reflecting molecular processes in myocardium under stem cell therapy.