The Transendocardial Autologous Cells (hMSC or hBMC) in Ischemic Heart Failure Trial (TAC-HFT)

Overview

The technique of transplanting progenitor cells into a region of damaged myocardium, termed cellular cardiomyoplasty, is a potentially new therapeutic modality designed to replace or repair necrotic, scarred, or dysfunctional myocardium. Ideally, graft cells should be readily available, easy to culture to ensure adequate quantities for transplantation, and able to survive in host myocardium; often a hostile environment of limited blood supply and immunorejection. Whether effective cellular regenerative strategies require that administered cells differentiate into adult cardiomyocytes and couple electromechanically with the surrounding myocardium is increasingly controversial, and recent evidence suggests that this may not be required for effective cardiac repair. Most importantly, transplantation of graft cells should improve cardiac function and prevent adverse ventricular remodeling. To date, a number of candidate cells have been transplanted in experimental models, including fetal and neonatal cardiomyocytes, embryonic stem cell-derived myocytes, tissue engineered contractile grafts, skeletal myoblasts, several cell types derived from adult bone marrow, and cardiac precursors residing within the heart itself. There has been substantial clinical development in the use of whole bone marrow and skeletal myoblast preparations in studies enrolling both post-infarction patients, and patients with chronic ischemic left ventricular dysfunction and heart failure. The effects of bone-marrow derived mesenchymal stem cells (MSCs) have also been studies clinically. Currently, bone marrow or bone marrow-derived cells represent highly promising modality for cardiac repair. The totality of evidence from trials investigating autologous whole bone marrow infusions into patients following myocardial infarction supports the safety of this approach. In terms of efficacy, increases in ejection fraction are reported in the majority of the trials. Chronic ischemic left ventricular dysfunction resulting from heart disease is a common and problematic condition; definitive therapy in the form of heart transplantation is available to only a tiny minority of eligible patients. Cellular cardiomyoplasty for chronic heart failure has been studied less than for acute MI, but represents a potentially important alternative for this disease.