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目的采用心肌内注射方法将骨髓间充质干细胞(BMSCs)植入到正常或慢性梗死心肌中后, 研究短期内植入细胞的分布和可利用度。方法采用选择性冠状动脉结扎方法建立大鼠慢性心肌梗死模型( n =9) 。1个月后, 采用心肌内注射方法将 111 铟 - 羟基喹啉 ( 111Indium- oxine, 111In) 同位素标记的自体 BMSCs (2×106/50μL)植入到慢性梗死心肌和正常对照心肌中( n =6) 。采用序列平面针孔闪烁扫描方法测定 BMSCs移植后 2 h、1 d、3 d、7 d 时的心肌 111In 的放射活性, 并计算植入细胞在心肌内的驻留率。于细胞移植术后第 7 天切取制备心脏横断面冷冻切片, 进行组织放射微成像(Micro- imaging)和组织病理学分析, 观察植入细胞在心肌内的分布情况。结果慢性心肌梗死(MI)组的心肌 111In 的放射活性在所有测定的时间点均显著高于正常对照组(P<0.01)。心肌放射强度实测值在经由各相应时间点 BMSCs细胞 111In 的自发泄漏率的体外标定值校正后, 计算得出植入的 BMSCs 细胞在慢性梗死心肌(MI 组)中的驻留率平均为 60%, 而在正常对照组心肌中细胞的驻留率只有 25%(P <0.01), 并在 7 d 的随访期中保持稳定。组织放射微成像和组织病理学分析都证实植入的 BMSCs 主要分布于由注射针头插入损伤或慢性心肌梗死所造成的纤维瘢痕组织中。结论心肌内细胞移植术后 7 d 内,被植入到慢性梗死心肌中的 BMSCs 细胞的可利用度高于被植入在正常心肌中的 BMSCs 细胞的可利用度。植入心肌内的 BMSCs 主要分布于由注射针头插入损伤和慢性心肌梗死导致的纤维瘢痕组织中。
Objective To investigate the distribution and availability of implanted cells in bone marrow after intramyocardial injection of bone marrow mesenchymal stem cells (BMSCs) into normal and chronic infarcted myocardium. Methods The model of chronic myocardial infarction was established by selective coronary artery ligation (n = 9). One month later, 111Indium-oxine (111In) isotope labeled autologous BMSCs (2 × 106 / 50μL) were implanted into the myocardium of chronic infarction and normal control myocardium by intramyocardial injection (n = 6). The radioactivity of 111In in myocardium at 2 h, 1 d, 3 d and 7 d after BMSCs transplantation was measured by serial plane pin-hole scintigraphy and the resident rate of implanted cells in myocardium was calculated. On the 7th day after the cell transplantation, the frozen section of the heart was cut out and analyzed by Micro-imaging and histopathology. The distribution of the implanted cells in the myocardium was observed. Results The radioactivity of 111In in myocardial infarction (MI) group was significantly higher than that in normal control group at all time points (P <0.01). Myocardial radioimmunity measurements were corrected by in vitro calibration of 111In spontaneous leak rates of BMSCs at respective time points and the average resident rate of implanted BMSCs in MI group was 60% , While the resident rate of cells in the normal control group was only 25% (P <0.01), and remained stable during the follow-up period of 7 days. Tissue radiation micro-imaging and histopathological analysis confirmed that the implanted BMSCs mainly distributed in the fibrous scar tissue caused by the injection needle insertion injury or chronic myocardial infarction. Conclusions Within 7 days after intracardiac transplantation, the availability of BMSCs implanted into chronic infarcted myocardium is higher than that of BMSCs implanted in normal myocardium. BMSCs implanted in the myocardium are mainly distributed in the fibrous scar tissue caused by the injection needle insertion injury and chronic myocardial infarction.