Key developments in stem cell therapy in cardiology.

A novel therapeutic strategy to prevent or reverse ventricular remodeling, the substrate for heart failure and arrhythmias following a myocardial infarction, is the use of cell-based therapy. Successful cell-based tissue regeneration involves a complex orchestration of cellular and molecular events that include stem cell engraftment and differentiation, secretion of anti-inflammatory and angiogenic mediators, and proliferation of endogenous cardiac stem cells. Recent therapeutic approaches involve bone marrow-derived mononuclear cells and mesenchymal stem cells, adipose tissue-derived stem cells, cardiac-derived stem cells and cell combinations. Clinical trials employing mesenchymal stem cells and cardiac- derived stem cells have demonstrated efficacy in infarct size reduction and regional wall contractility improvement. Regarding delivery methods, the safety of catheter-based, transendocardial stem cell injection has been established. These proof-of-concept studies have paved the way for ongoing pivotal trials. Future studies will focus on determining the most efficacious cell type(s) and/or cell combinations and the mechanisms underlying their therapeutic effects.