Cell-based therapies for cardiac disease: a cellular therapist's perspective

Cell-based therapy is an exciting, promising, and a developing new treatment for cardiac diseases. Stem cell-based therapies have the potential to fundamentally transform the treatment of ischemic cardiac injury and heart failure by achieving what would have been unthinkable only a few years ago-the Holy Grail of myocardial regeneration. Recent therapeutic approaches involve bone marrow (BM)-derived mononuclear cells and their subsets such as mesenchymal stem/stromal cells (MSCs), endothelial progenitor cells as well as adipose tissue-derived MSCs, cardiac tissue-derived stem cells, and cell combinations. Clinical trials employing these cells have demonstrated that cellular therapy is feasible and safe. Regarding delivery methods, the safety of catheter-based, transendocardial and -epicardial stem cell injection has been established. However, the results, while variable, suggest rather modest clinical efficacy overall in both heart failure and ischemic heart disease, such as in acute myocardial infarction. Future studies will focus on determining the most efficacious cell type(s) and/or cell combinations and the most reasonable indications and optimal timing of transplantation, as well as the mechanisms underlying their therapeutic effects. We will review and summarize the clinical trial results to date. In addition, we discuss challenges and operational issues in cell processing for cardiac applications.