The utility of magnetic resonance imaging in cardiac tissue regeneration trials.

The past decade has seen the emergence of paradigm shifts in concepts involving cardiovascular tissue regeneration, including the idea that adult stem cells originate in hematopoietic or bone marrow cells, the belief that even adult organs, such as the heart and nervous system, are capable of post-mitotic regeneration, and the concept of inherent plasticity in cells that have undergone limited lineage differentiation. There has consequently been a flurry of proposed regenerative strategies, and safety and limited efficacy data from both animal and limited human trials have been presented. The drive to push these advances from the bench to the bedside has created a unique environment where the therapeutic agents, delivery approaches, and methods of measuring efficacy (often imaging technology) are evolving practically in parallel. The encouraging results of recent cell-therapy trials should therefore be assessed cautiously and in consonance with an understanding of the advantages and limitations of delivery strategies and end points. Arguably, the use of imaging technologies to evaluate surrogate end points might help overcome the difficulty posed by large sample sizes required for hard end point trials in cardiovascular therapeutics. Cardiac magnetic resonance imaging is one of the most sensitive techniques available to assess spatial and temporal changes following local or systemic therapies, and the availability of a bevy of complementary techniques enables interrogation of physiology, morphology, and metabolism in one setting. We contend that cardiac magnetic resonance imaging is ideally suited to assess response to myocardial regeneration therapy and can be exploited to yield valuable insights into the mechanism of action of myocardial regeneration therapies.