Optimizing stem cell therapy for cardiac repair following a myocardial infarction

An extensive myocardial infarction (MI) frequently results in post-infarct remodelling, which can lead to heart failure. Emergency percutaneous coronary intervention (PCI) has reduced the mortality of ST-elevation MI, and the use of beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, and anticoagulants has improved the morbidity. However, progressive ventricular dysfunction is increasingly common. New treatments are urgently needed for MI survivors to prevent pathological remodelling and functional loss. Replacing the cells lost during the infarction might limit detrimental remodelling, but none of the proposed treatments have been shown to completely restore beating cardiomyocytes. Stem cell transplantation was originally proposed to replace these lost cells, but extensive animal and human studies have suggested that the benefits of cell implantation were the result of paracrine effects. Several stem cell populations that improved ven- tricular function in preclinical studies have also been beneficial in clinical trials to treat post-MI remodelling. However, most of these trials had mixed results, highlighting the need for further research into the mechanisms responsible for improved cardiac function and the need to develop new treatment strategies to augment the beneficial effects of stem cell transplantation.