微囊化重组CHO细胞移植促进大鼠心肌梗死后血管新生的实验研究

目的在大鼠心肌梗死部位植入微囊化重组中华仓鼠卵巢（chinese hamster ovary，CHO）细胞，观察其分泌的血管内皮细胞生长因子（VEGF）是否可以促进心肌梗死部位的血管新生，改善心功能。方法通过质粒转染的方法构建可以分泌VEGF的重组CHO细胞系，用微囊包裹，观察微囊内细胞的生长及分泌情况。制备大鼠心肌梗死模型，随机将48只8周龄SD雄性大鼠分成微囊化细胞移植组（MC—CHO组）、单纯细胞移植组（CHO组）、空微囊移植组（MC组）和无血清培养基移植组（对照组），每组12只。移植3周后检测心功能改善情况，病理切片观察微囊结构及囊内细胞存活情况，注射部位微血管计数比较促血管新生效果。结果体外检测可见重组CHO细胞在微囊生长迅速，第8d时培养上清中VEGF达3852pg／ml；移植3周后MC—CHO组左心室大小和心功能明显好于其它3组，差异有统计学意义（P〈0．05）；局部微血管密度MC—CHO组较CHO组、MC组和对照组明显增加（22．3±3．1vs．15．6±2．8，11．4±2．5和13．2±2．7个／每高倍视野，P〈0．05）；组织学检查可见微囊结构完整，内有存活且具有分泌功能的CHO细胞。结论微囊化重组CHO细胞移植可促进大鼠心肌梗死后血管新生，改善心功能。

Transplantation of Microencapsulated Recombinanted Chinese Hamster Ovary Cells Promotes Angiogenesis in Post-infarction Myocardium in Rats

Objective To transplant the microencapsulated recombinanted Chinese hamster ovary （CHO） cells into the infracted myocardium of rodent animals and investigate whether vascular endothelial growth factor （VEGF） secreted by the implanted CHO cells could augment angiogenesis and improve cardiac function. Methods The cDNA of VEGF was transferred into CHO cells with plasmid stable transfection. After microencapsulation, the cell growth in microcapsules and the VEGF level in the culture supernatant were evaluated. Two weeks after myocardial infarction, the microencapsulated CHO cells （MC-CHO group） were implanted into the border of infracted myocardium, as well as similar amount of CHO cells （CHO group）, blank microcapsule （MC group） and non-serum culture medium （control group） as controls, 12 rats per group. The cardiac function improvement was evaluated 3 weeks after transplantation, while the survival status of implanted CHO cells, in situ secretion of VEGF and capillary density were assayed by histology. Results CHO cells could grow and proliferate after microencapsulation. The secretion of VEGF was detectable in culture media supernatant, with the highest concentration of 3 852 pg/ml at day 8. As compared to the other three groups, the left ventricular dimension and cardiac function were significantly improved in MC-CHO group 3 weeks after transplantation. The capillary density of MC-CHO group were increased significantly than those of CHO group, MC group and control group （22.3±3.1 vs. 15.6±2.8, 11.4±2.5, 13.2±2.7 vessels per 0.13 mm^2, P〈0.05）. The implanted microcapsule maintained its original shape and protected the CHO cells in it. Conclusion Microencapsulaed recombinanted CHO cells transplantation might be a promising approach to augment angiogenesis and improve the cardiac function in infarction myocardium.