兔心肌梗死后自体骨髓干细胞移植时机的确立*★

背景：心肌梗死发生后心肌组织将经历炎症反应、心肌纤维化等复杂病理过程，在此期间移植的骨髓干细胞其分化及存活情况均会受到影响。目的：实验选择兔心肌梗死后不同时间点行自体骨髓干细胞移植，通过心脏病变区域组织学变化分析最佳移植时机。设计、时间及地点：随机对照细胞观察，于2005-06/2006-04在东南大学试验动物中心完成。材料：清洁级雄性青紫蓝兔36只，随机分成细胞移植组、模型对照组，每组又设立造模后即刻、造模后2周、造模后4周3个亚组，6只/时间点。方法：两组兔均采用液氮冷冻法建立心肌梗死模型。细胞移植组自双侧髂骨抽取骨髓，FICOLL法分离骨髓单个核细胞，加入5-氮杂胞苷予以诱导，移植前行Brdu标记，分别于造模后即刻、2周、4周在心肌梗死部位与正常心肌交界处分4点注入制备好的骨髓干细胞悬液，细胞总数1.0×107个。模型对照组按同样方式于对应时间点注入等量DMEM培养液。主要观察指标：移植后4周心肌组织病理学变化。结果：免疫组织化学染色结果显示，造模后2周、4周细胞移植组均可见Brdu标记细胞，造模后即刻细胞移植组呈阴性。苏木精-伊红染色结果显示，造模后2周细胞移植组出现心肌样细胞，造模后即刻、4周细胞移植组均呈阴性。模型对照组于各时间点仅观察到瘢痕、纤维组织的出现，未见特异性结构。结论：兔心肌梗死后第2周是比较适宜的移植时机，植入后的自体骨髓干细胞可向心肌样细胞方向分化。

Optimal time of autologous bone marrow stem cell transplantation in rabbits after myocardial infarction

BACKGROUND: After myocardial infarction, inflammatory reaction and myocardial fibrosis can be detected in myocardium. During this process, differentiation and survival of transplanted bone marrow stem cells can be affected. OBJECTIVE: To study the optimal time for bone marrow stem cell transplantation in rabbits after myocardial infarction by analyzing histological changes in cardiac lesion region.DESIGN, TIME AND SETTING: A randomized control cell investigation was performed at the Experimental Animal Center of Central South University from June 2005 to April 2006. MATERIALS: Totally 36 clean male pigmented rabbits were divided into model control group and cell transplantation group. Each group was divided into 3 subgroups according to time points (immediately, 2 weeks and 4 weeks after establishing models), 6 rabbits in each time point. METHODS: Rabbit models of myocardial infarction were established by liquid nitrogen frozen in both groups. Bone marrow was extracted from bilateral iliac bone in the cell transplantation group. Mononuclear cells were harvested from bone marrow by FICOLL method, induced by 5-aza and labeled by Brdu. Subsequently, bone marrow stem cell suspension (number of cells 1.0×107) was injected into the juncture between infracted region and normal myocardium at 4 points immediately, 2 weeks and 4 weeks after establishing models. Using the same methods, DMEM of the same volume was injected into rabbits of the model control group at the corresponding time points. MAIN OUTCOME MEASURE: Pathological changes in myocardium 4 weeks after transplantation. RESULTS: Immunohistochemical staining demonstrated that Brdu-labeled cells were detected in the cell transplantation group 2 weeks and 4 weeks after establishing models, whereas Brdu-labeled cells were negative in the cell transplantation group immediately after establishing models. Hematoxylin and eosin staining confirmed that myocardium-like cells were found in the cell transplantation group 2 weeks after establishing models, whereas negative in the cell transplantation group immediately and 4 weeks after establishing models. Only scar and fibrous tissues were detected, but no specific structure was presented in the model control group at each time point. CONCLUSION: The optimal time for bone marrow cell transplantation is at week 2 after myocardial infarction in rabbit models. Autologous bone marrow stem cells can differentiate into myocardium-like cells after transplantation.