尾静脉注射骨髓间充质干细胞修复衰老小鼠颅骨损伤

Tail vein injection of bone marrow mesenchymal stem cells for repair of skull injury in aging mice

背景:局部应用骨髓间充质干细胞具有促进骨组织再生修复的能力,但是经静脉注射途径是否能发挥显著作用,及其对于不同生理年龄状态下的骨组织再生修复能力尚需明确。目的:探索尾静脉注射骨髓间充质干细胞对年轻小鼠与衰老小鼠颅骨损伤修复能力的影响。方法:取40只1月龄昆明小鼠作为年轻小鼠,40只12月龄昆明小鼠作为衰老小鼠,再随机分为年轻小鼠实验组、年轻小鼠对照组、衰老小鼠实验组、衰老小鼠对照组。构建颅骨缺损模型,术后1,8,15 d实验组小鼠尾静脉注射0.2 mL骨髓间充质干细胞悬液(1×10^(10) L^(-1));对照组小鼠注射等量生理盐水。术后1周和3周取颅骨缺损标本,进行形态学、组织病理学、光学、免疫组织化学观察分析。结果与结论:①Micro-CT检测:术后1周,年轻小鼠与衰老小鼠骨缺损区域大小无显著差异;术后3周,实验组骨缺损区域孔径显著缩小;②苏木精-伊红染色、Masson染色:术后1周,缺损区域内有新生胶原纤维;术后3周,缺损区域出现新生骨基质,其中实验组显著多于对照组;③非线性光学显微镜检测:术后3周,缺损区域胶原蛋白水平比较:年轻小鼠实验组>年轻小鼠对照组;衰老小鼠实验组>衰老小鼠对照组;④免疫组化分析:术后1周和3周,年轻小鼠实验组的Sirt1蛋白表达均低于年轻小鼠对照组;术后1周,衰老小鼠实验组的Sirt1蛋白表达高于衰老小鼠对照组;术后3周,衰老小鼠实验组的Sirt1蛋白表达低于衰老小鼠对照组;⑤结果表明,经尾静脉注射骨髓间充质干细胞明显促进不同年龄段小鼠颅骨缺损修复,其主要通过激活小鼠体内Sirt1表达而促进骨再生。

BACKGROUND:Local application of bone marrow mesenchymal stem cells has the ability to promote bone tissue regeneration and repair;however,whether it could play a significant role via vein injection and its ability of bone tissue regeneration and repair at different ages still need to be clarified.OBJECTIVE:To explore the effects of bone marrow mesenchymal stem cells on the repair ability of skull injury in young and aging mice via vein injection.METHODS:Totally 401-month-old Kunming mice were obtained as young mice,and 4012-month-old Kunming mice were obtained as aging mice.The mice were divided into young experimental group,young control group,aging experimental group,and aging control group.The bone defect was made in the cranium of the mice.At 1,8,and 15 days after surgery,0.2 mL bone marrow mesenchymal stem cell suspension(1×10^(10) L^(-1))was injected into the tail vein of mice in the experimental groups;meanwhile,an equal volume of saline was used in the control groups via tail vein.The mice were sacrificed at 1 and 3 weeks after surgery.The specimens were repaired for the following experiments:morphological,histopathological,optical,and immunohistochemical analyses.RESULTS AND CONCLUSION:(1)Micro-CT imaging:At 1 week after surgery,there was no significant difference in the size of bone defect area between the young and aging groups,and the size of the bone defect area was reduced significantly in the experimental groups at 3 weeks after surgery.(2)Hematoxylineosin staining and Masson staining:The collagen fibers appeared at 1 week after surgery;meanwhile,the bone matrix emerged at 3 weeks after surgery in the defect area.The collagen fibers and the bone matrix were significantly more in the experimental groups than those in the control groups.(3)Non-linear light microscopy:At 3 weeks after the operation,the comparison of collagen content in the defect area was as follows:young experimental group>young control group;aging experimental group>aging control group.(4)Immunohistochemical analysis:At 1 and 3 weeks after operation,Sirt1 protein expression was more in the young groups than that in the aging groups.At 1 week,the Sirt1 protein expression was more in the experimental groups than that in the control groups.At 3 weeks,the Sirt1 protein expression was less in the aging experimental group than that in the aging control group.(5)It is concluded that bone marrow mesenchymal stem cells promoted the repair of skull defects in the mice of different ages significantly via the tail vein injection,which mainly promotes bone regeneration by activating Sirt1 expression in mice.