Congestive eat Failure (CHF) is one of the leading causes of mortality and morbidity in developed countries. Despite the major advances in prophylaxis, medical therapy and revascularization procedures for coronary artery disease, a substantial proportion of patients suffer from HF in the aftermath of myocardial infarction . It is estimated that more than 250,000 people in the United States die each year from CHF. The prognosis for CHF patients is poor, with a median survival after onset of only 1.7 years in men and 3.2 years in women. Current treatments for HF are of limited effectiveness and do not substantially improve patients' condition, while the availability of hearts for transplantation is severely limited.

Regeneration of all or part of the akinetic scar tissue and/or blood supply to damaged, areas formed during the progression of CHF should improve cardiac function and impede progressive left ventricular (LV) remodeling. The discovery that stem and progenitor cells may possess the capability of promoting tissue regeneration in ischemic tissue has led to a large number of studies devoted to the evaluation of the use of stem/progenitor cell therapy as an effective treatment for severe myocardial diseases.

Two promising sources of cells that may provide regeneration of damaged myocardium include skeletal myoblast and mesenchymal stem cells.

Extensive studies in large and small animals have shown improvement in heart function in animals where myocardial infarction was created and stem cells or myoblast were injected.

It is estimated that more than a thousand patients have been treated with various stem cells under different protocols.

In early trials, stem cells transplantation was combined with Coronary artery bypass grafting. Menasche first reported the implantation of autologous skeletal myoblasts into the postinfarction scar during a coronary artery bypass surgery. In 10 patients a mean of 871 x 106 autologous myoblasts were injected into the scar during bypass grafting in that study. There was improvement in contraction and viability in the cell-implanted scars at an average follow-up of 10.9 months; however four patients developed episodes of ventricular tachycardia early after the surgery that was managed by defibrillator implantation. A later larger Phase 2 trial showed that the incidence of arrythmias was no greater in the cell transplant group than the placebo group.

Stamm on the other hand, injected purified autologous CD133+ stem cells into the infarct border, in six patients who were good candidates for CABG. All patients experienced an acute transmural MI between 10 days and 3 months prior to the procedure. No patient complained of ventricular arrhythmias at 9-10 months follow-up, although there was little effect on local contractibility in the study. Notwithstanding, all patients reported an improvement to their lifestyle. The improved myocardial perfusion observed was a likely consequence of the angiogenic stimulation by CD133+ cells.