Effects of timing on intracoronary autologous bone marrow-derived cell transplantation in acute myocardial infarction: a meta-analysis of randomized controlled trials

Background: Several cell-based therapies for adjunctive treatment of acute myocardial infarction have been investigated in multiple clinical trials, but the timing of transplantation remains controversial. We conducted a meta-analysis of randomized controlled trials to investigate the effects of timing on bone marrow-derived cell (BMC) therapy in acute myocardial infarction (AMI). Methods: A systematic literature search of PubMed, MEDLINE, and Cochrane Evidence-Based Medicine databases from January 2000 to June 2017 was performed on randomized controlled trials with at least a 3-month follow-up for patients with AMI undergoing emergency percutaneous coronary intervention (PCI) and receiving intracoronary BMC transfer thereafter. The defined end points were left ventricular (LV) ejection fraction, LV end-diastolic and end-systolic index. The data were analyzed to evaluate the effects of timing on BMC therapy. Results: Thirty-four RCTs comprising a total of 2,307 patients were included; the results show that, compared to the control group, AMI patients who received BMC transplantation showed significantly improved cardiac function. BMC transplantation 3-7 days after PCI (+3.32%; 95% CI, 1.91 to 4.74; P < 0.00001) resulted in a significant increase of left ventricular ejection fraction (LVEF). As for the inhibitory effect on ventricular remodeling, BMC transplantation 3-7 days after PCI reduced LV end-diastolic indexes (-4.48; 95% CI, -7.98 to -0.98; P = 0.01) and LV end-systolic indexes (-6.73; 95% CI, -11.27 to -2.19; P = 0.004). However, in the groups who received BMC transplantation either within 24 hours or later than 7 days there was no significant effect on treatment outcome. In subgroup analysis, the group with LVEF <= 50% underwent a significant decrease in LV end-diastolic index after BMC transplantation (WMD = -3.29, 95% CI, -4.49 to -2.09; P < 0.00001); the decrease was even more remarkable in the LV end-systolic index after BMC transplantation in the group with LVEF <= 50% (WMD = -5.25, 95% CI, -9.30 to -1. 20; P = 0.01), as well as in patients who received a dose of 10<^>7-10<^>8 cells (WMD = -12.99, 95% CI, -19.07 to -6.91; P < 0.0001). In the group with a follow-up of more than 12 months, this beneficial effect was significant and increased to a more pronounced effect of +3.58% (95% CI, 1.55 to 5.61; P = 0.0006) when compared with control. Conclusions: In this meta-analysis, BMC transfer at 3 to 7 days post-AMI was superior to transfer within 24 hours or more than 7 days after AMI in improving LVEF and decreasing LV end-systolic dimensions or LV end-diastolic dimensions. It is more effective in patients with lower baseline LVEF (<= 50%) and the effect can last more than 12 months.