Myocardial infarction leads to an irreversible loss of vital myocardial cells. The transplantation of new cardiomyocytes into the heart was first described over 20 years ago and represents a straightforward approach to remuscularize a damaged heart. Due to the lack of human cells a clinical application seemed ambitious; however, dramatic progress in stem cell biology over the last two decades has paved the way towards a clinical application. This is especially important as the prognosis for patients with terminal heart failure is still poor. The transplantation of either cardiomyocytes or engineered heart tissue derived from pluripotent stem cells (either embryonic stem cells or induced pluripotent stem cells) might represent a new regenerative approach. Transplantation of either cells or tissue constructs has now been evaluated in several preclinical models, which have demonstrated that an injured heart can be (partially) remuscularized; however, major hurdles towards a clinical application are the transplantation-related occurrence of arrhythmia, the potential tumorigenicity of pluripotent cells and the required immunosuppression. Several groups are working hard to solve these problems and we are optimistic that the first clinical studies will take place within the next few years.
