Even after optimal reperfusion strategies implementing percutaneous coronary intervention (PCI) with stent implantation and modern medical regimen for patients with acute myocardial infarction, myocardial salvage is often incomplete and adverse ventricular remodeling with subsequent heart failure develops. The transplantation of autologous bone marrow stem cells (BM-SCs) via the intracoronary delivery route after PCI of the infarct related artery (IRA) has been investigated in several observational studies which proved the safety and feasibility of the method. The results of the randomized studies were rather controversial. The BOOST study (Bone Marrow transfer to enhance ST-elevation infarction regeneration) was the first randomized study with patients receiving either bone-marrow derived mononuclear cells or placebo 5 days after primary PCI. The improvement of the ejection fraction reported in the cell infusion group at 6 months was attenuated during a follow-up study of 18 months. Of note, a similar restenosis rate (13%) was reported between the 2 groups
