Intramyocardial Transplantation of Bone Marrow Stem Cells in Addition to Coronary Artery Bypass Graft (CABG) Surgery

Overview

In spite of the fact that the post-myocardial infarction survival rate has improved with recent medical advances, reduced heart function attributed to irreversible loss of viable cardiomyocytes is still a major clinical problem. The aim of the current study is to determine whether intramyocardial injection of autologous CD133+ bone marrow stem cells yields a functional benefit in addition to coronary artery bypass graft (CABG) surgery in patients with chronic ischemic coronary artery disease.

Beginning in 2001, a phase-1 equivalent feasibility and safety evaluation of intramyocardial injection of autologous CD133+ bone marrow cells during elective CABG surgery was conducted at Rostock University. No procedure-related adverse events were observed and there was some improvement of myocardial contractility and perfusion. It was decided to proceed with a controlled efficacy testing, comparing the outcome of standard CABG surgery with that after CABG and CD133+ cell injection. The results of that study indicate that the additional cell injection yields a better left ventricular contractility than CABG alone (LVEF = 47.1±8% vs. 41.3±9% at 6 months). Although this result is encouraging, the trial had several limitations that hamper interpretation of the data. Most notably, no sham-injection of placebo material was performed in the control group, and standard 2D echocardiography served as the only measurement of global LV contractility. However, there were no procedure-related complications up to 18 months postoperatively, especially no new ventricular arrhythmia or neoplasia. Therefore, a prospective, double blinded, randomized, and placebo-controlled multi-center trial will be conducted in Germany, employing current state-of-the art measurement of global and regional LV contractility by cardiac MRI. The following hypothesis will be tested: "Patients who undergo CABG \& CD133+ cell injection do not have a higher LV ejection fraction than patient who undergo CABG alone, measured 6 months after the operation". A power analysis based on the previous trial results indicated that 71 patients per group need to be enrolled so as to reject the null-hypothesis with sufficient statistical power. A total of 142 patients will therefore be enrolled in the study. Patients will be randomized in a 1:1 ratio to undergo CABG surgery in conjunction with either intramyocardial injection of autologous CD133-enriched bone marrow cells or placebo. Bone marrow will be harvested one or two days prior to surgery and a CD133-enriched cell product (or placebo) will be prepared at a central cell processing GMP unit. Bypass surgery will be performed and the investigational product will be injected in the border zone of the infarcted myocardium. Random allocation will be performed in the cell production facility, so that neither the patient nor the surgeon nor any of the personnel involved in follow-up examinations will know whether the cell product or placebo was administered. The primary outcome parameter (LVEF at 6 months) will be measured by cardiac MRI, and secondary outcome parameters include physical exercise capacity, cardiac function, safety and Quality of Life (QoL).