Implantation of CD133+ stem cells in patients undergoing coronary bypass surgery: IMPACT-CABG pilot trial.

BACKGROUND: The Implantation of Autologous CD133(+) Stem Cells in Patients Undergoing CABG (IMPACT-CABG) trial is investigating the feasibility, safety, and efficacy of intramyocardial injections of autologous CD133(+) stem cells during coronary artery bypass grafting (CABG) in patients with chronic ischemic cardiomyopathy. We are reporting the results of the first 5 open-label patients.

METHODS: Bone marrow was harvested from iliac crests and stem cells were isolated using the CliniMACS CD133(+) Reagent System (Miltenyi Biotec, GmbH, Bergisch Gladbach, Germany). Patients received CABG, followed by CD133(+) cellular injection in the revascularized hypokinetic myocardium.

RESULTS: Five males New York Heart Association (NYHA) class III patients aged 64 ± 10 years were treated. Immunomagnetic cell processing allowed an average of 100 ± 48-fold enrichment in CD133(+) cells, with 92 ± 11% recovery after selection. Mean number of CD133(+) cells injected was 8.4 ± 1.2 million. There were no protocol-related complications during the 18-month follow-up and all patients improved to NYHA class I. Six-month echocardiography showed no significant improvement in left ventricular ejection fraction (34 ± 2% at baseline vs 38 ± 12%: P = 0.50). However, cardiac magnetic resonance showed that systolic wall thickening increased from 15.0 ± 10.5% to 29.0 ± 22.1% (P = 0.01). In addition, mean segmental wall thickness also improved in comparison with baseline (10.7 ± 2.7% to 12.1 ± 4.8%; P < 0.01).

CONCLUSIONS: This work represents the first Canadian experience with CD133(+) stem cells for the treatment of chronic ischemic cardiomyopathy. These results demonstrate the initial safety and feasibility of the IMPACT-CABG pilot trial. Subsequent patients are now being randomized to receive either CD133(+) stem cell or placebo.