In LATE-TIME (Late Timing in Myocardial Infarction), patients with left ventricular (LV) ejection fraction ≤45% received intracoronary autologous bone marrow cells or placebo 2 to 3 weeks after reperfused ST-segment-elevation myocardial infarction. Although the overall results did not show benefit, the prevalence of CD34+, CD133+, and CD45+/CXCR4 (C-X-C chemokine receptor 4) cells and higher endothelial colony formation units correlated with improved LV function. In addition, comorbidities negatively altered bone marrow cells composition, function, and surface marker expression. Last, in the TIME trial (Timing in Myocardial Infarction), patient received intracoronary autologous bone marrow cells or placebo 3 or 7 days post-ST-segment-elevation myocardial infarction. Infarc size reduction at 6 months was correlated with CD31+ cell number and colony formation unit, suggesting additional predictive markers.