目的:讨论心肌梗死后经冠脉骨髓单个核细胞移植的最佳时间段。方法:建立大鼠心肌梗死模型,观察心肌梗死后1d、1周、2周及4周心脏的组织学改变,并且分别在心肌梗死后1d(n=10)、1周(n=10)、2周(n=10)及4 周(n=10)非选择性经冠脉内移植骨髓单个核细胞或PBS,4周后观察梗死面积大小及瘢痕厚度。超声心动图观察移植前后心功能和重构指标变化。结果:心肌梗死后1d炎症反应最严重,4周时瘢痕扩展并变薄(P<0.05)。心肌梗死后1周及2周,细胞移植组梗死面积缩小,胶原厚度增加最明显(P<0.05);2周组心功能改善最明显(P<0.05);1 周组其次(P<0.05)。结论:心肌梗死后1~2周进行骨髓干细胞移植得益最大。 OBJECTIVE: To discuss the optimal time period for transplanting coronary bone marrow mononuclear cells after myocardial infarction. Methods: The model of myocardial infarction in rats was established. The histological changes at 1, 1, 2 and 4 weeks after myocardial infarction were observed. The changes of cardiac histopathology were observed at 1 day (n = 10), 1 week After 2 weeks (n = 10) and 4 weeks (n = 10) non-selective intracoronary transplantation of bone marrow mononuclear cells or PBS, infarct size and scar thickness were observed after 4 weeks. Changes of cardiac function and remodeling indexes before and after transplantation were observed with echocardiography. Results: Inflammatory reaction was most serious at 1 day after myocardial infarction. Scars expanded and thinned at 4 weeks (P <0.05). At 1 and 2 weeks after myocardial infarction, the infarct size of the cell transplantation group was reduced and the collagen thickness was the most obvious increase (P <0.05). The improvement of cardiac function was the most obvious in the 2-week group (P <0.05), followed by the 1-week group (P <0.05). Conclusions: Bone marrow stem cell transplantation has the best benefit 1 to 2 weeks after myocardial infarction.