Randomized Controlled Trial of Intramuscular or Intracoronary Injection of Autologous Bone Marrow Cells into Scarred Myocardium

Introduction Previous studies on the transplantation of autologous bone marrow cells (BMC) in patients with chronic ischemic heart disease have focused on their effects on viable, peri-infarct tissue. We conducted a blinded, randomized controlled study to investigate whether intramuscular (IM) or intracoronary (IC) administration of BMC into non-viable scarred myocardium during coronary artery bypass grafting (CABG) improves contractile function of scar segments compared with CABG alone. Methods 63 elective CABG patients, with established myocardial scars diagnosed by dobutamine stress echocardiography (DSE) and confirmed at surgery, were randomized into control, IM or IC treatment groups. The BMC obtained at the time of surgery were injected into the middepth of the scar in the IM group or via the graft conduit supplying the scar in the IC group. Contractile function of the scar segments was assessed by DSE before and 6 months after treatment. Cardiac magnetic resonance imaging was also performed in the last 33 patients at the same time points. Results 12.5-29.4% of patients showed improved wall motion in at least one scar segment after BMC treatment but this effect was similar to that in the control group. Quantitatively, %systolic fractional thickening in scar segments did not improve with BMC administration. Scar transmurality, %infarct volume, left ventricular volumes and ejection fractions were also not improved by BMC. Discussion Autologous BMC, injected directly into the scar or the artery supplying the scar, do not improve contractility of non-viable scarred myocardium. Furthermore, BMC do not reduce scar size nor improve left ventricular function.