AIMS: The study assessed 4-year outcomes of intramyocardial injections of autologous bone marrow-derived mesenchymal stromal cells (MSCs) in patients with ischaemic heart failure.

METHODS AND RESULTS: The MSC-HF trial was a randomized, double-blind, placebo-controlled trial. Patients were randomized 2:1 to intramyocardial injections of MSCs or placebo. The primary endpoint was change in left ventricular end-systolic volume (LVESV), measured by magnetic resonance imaging or computed tomography. Sixty patients aged 30-80 years with ischaemic heart failure, New York Heart Association class II-III, left ventricular ejection fraction (LVEF) <45% and no further treatment options were randomized. Patients were followed clinically for 12 months and in addition 4-year data of hospitalizations and survival were retrieved. After 12 months, LVESV was significantly reduced in the MSC group and not in the placebo group, with difference between groups of 17.0 ± 16.2 mL (95% confidence interval 8.3-25.7, P = 0.0002). There were also significant improvements in LVEF of 6.2% (P < 0.0001), stroke volume of 16.1 mL (P < 0.0001) and myocardial mass (P = 0.009) between groups. A significant dose-response effect was also observed. Moreover, a significant reduction in the amount of scar tissue and quality of life score in the MSC group but not in the placebo group was observed. After 4 years, there were significantly fewer hospitalizations for angina in the MSC group and otherwise no differences in hospitalizations or survival. No side effects were identified.

CONCLUSIONS: Intramyocardial injections of autologous bone marrow-derived MSCs improved myocardial function and myocardial mass in patients with ischaemic heart failure.