Paracrine Hypothesis and Cardiac Repair

Last two decades of research has seen the emergence and progress of stem cells from a myth to reality and their expediency in the clinical perspective as an effective therapeutic modality. Despite immense progress and promising results from experimental animal studies and clinical trials, the provocative underlying mechanism of their functional efficacy has led to diverging opinions and indulging the researchers into a continuous discussion. With controversies clouding the potential of stem cells to adopt morpho functionally competent cardiac phenotype, paracrine activity of the transplanted stem cells has been put forth as an alternative mechanism associated with the beneficial outcome of cell therapy. Although unique paracrine activity of a cell, besides endocrine activity and juxtacrine activity, constitutes an integral part of the cell-to-cell communication, the release of trophic factors from the transplanted cells favorably modulates the local microenvironment in the cell transplanted region in the infarcted heart and positively impact the integration and reparability of the cell graft.