Immunosuppression and xenotransplantation of cells for cardiac repair

The death of highly vulnerable cardiomyocytes during ischemia leads to cardiac dysfunction, including heart failure. Due to limited proliferation of adult mammalian cardiomyocytes, the dead myocardium is replaced by noncontractile fibrotic tissue. Introducing exogenous cells to participate in the regeneration of infarcted myocardium has thus been proposed as a novel therapeutic approach. In view of the availability of various xenogeneic cells and fewer ethical and political concerns that surround human embryonic stem cells and fetal cardiomyocytes, cellular xenotransplantation may be a potential alternative approach for cardiac repair in humans. However, one of the most daunting challenges of xenotransplantation is immunorejection. This article summarizes the progress in cellular xenotransplantation for cardiac repair in experimental settings and the current understanding of possible immune responses following the engraftment of xenogeneic cells. The public attitude towards xenotransplantation is reportedly more favorable to receiving cells or tissues than a whole organ, but many scientific obstacles need to be overcome before the utilization of xenogeneic cells for cardiac repair in patients with heart disease becomes applicable to clinical practice. (C) 2004 by The Society of Thoracic Surgeons.