局部植入辛伐他汀诱导自体骨髓间充质干细胞归巢修复大鼠颅骨缺损

目的探讨局部植入辛伐他汀修复大鼠颅骨极限骨缺损的机制，即诱导自体骨髓间充质干细胞（BMSC）归巢。方法辛伐他汀5mg加聚乳酸20mg或单纯聚乳酸20mg分别溶解于200μl丙酮，制备辛伐他汀聚乳酸复合材料或单纯聚乳酸材料。16只SD大鼠尾静脉注射绿色荧光蛋白（GFP）标记的BMSC（GFP-BMSC）作为示踪细胞，48h后制作大鼠颅骨极限缺损模型，并植入辛伐他汀-聚乳酸复合材料（n=8）和单纯聚乳酸材料（n=8）进行修复。2周后经小动物活体荧光成像系统检测缺损处绿色荧光信号，冰冻切片荧光显微镜下观察辛伐他汀组（n=4）和对照组（n=4）缺损处GFP-BMSC归巢。颅骨脱钙后经免疫组化染色检测辛伐他汀组（n=4）和对照组（n=4）缺损处骨形态发生蛋白-2（BMP-2）表达。结果小动物活体荧光成像系统检测显示，辛伐他汀组缺损处有较强的绿色荧光信号，对照组缺损处绿色荧光信号较弱；冰冻切片荧光显微镜下观察发现，辛伐他汀组缺损处较对照组缺损处GFP阳性细胞数量明显增加；免疫组化检测发现，辛伐他汀组BMP-2表达增加。结论局部植入辛伐他汀可诱导自体BMSC归巢至缺损部位并参与修复，其诱导归巢过程可能与BMP-2表达上调有关。

Locally applied simvastatin recruits bone marrow stromal cells to repair rat calvarial defect

Objective To investigate that locally applied simvastatin promotes bone healing by recruiting autogenous bone marrow stromal cells （BMSC） to the defect. Methods Simvastatin （5 mg） compounded with polylactic acid （PLa, 20 mg） or only PLA （20 mg） was dissolved in acetone （200μl） to prepare locally applied materials （simvastatin-PLA scaffolds, PLA scaffolds）. Green fluoresent protein （GFP） BMSCs were transplanted into sixteen Sprague Dawley rats through the tail vein as tracer cells. After 48 hours, critical-sized calvarial defects （φ = 5 rnrn） were surgically created on rats and implanted with simvastatin-PLA scaffolds （n = 8） or PLA scaffolds （n = 8） as control. Fourteen days later, GFP signals in the defect were detected using a fluorescence-based small animal imaging system and rat calvarial bones were sliced and observed under a fluorescence microscope （n = 4）. The expression of bone morphogenetic protein 2 （BMP-2） in the defect area was detected by imrnunohistochemistry staining （n= 4）. Results Intense GFP signal was detected in the rat defect region 14 days after simvastatin implantation, while tenuous GFP signal was presented in the control group. Frozen sections histology of the defect region confirmed the existence of GFP-BMSCs in the simvastatin group under fluorescence microscopy. The expression of BMP-2 was up-regulated in the simvastatin group. Conclusions Locally applied simvastatin can recruit autogenous osteogenic stem ceils to participate bone healing and BMP-2 may mediate the process of recruitment.