兔肩袖腱骨愈合过程中基质细胞衍生因子1的表达及作用机制

Expression and action mechanism of stromal cell-derived factor 1 in tendon-bone healing of rabbit rotator cuff

背景:近年在腱骨损伤领域部分学者将基质细胞衍生因子1搭载在组织工程支架上用以促进腱骨愈合,取得了较好的成效,但在基质细胞衍生因子1促进腱骨愈合机制及自然愈合过程中其是否参与修复,目前尚未明确。目的:研究兔肩袖全层冈上肌断裂后腱骨愈合过程中基质细胞衍生因子1表达,及其在腱骨损伤时对干细胞的迁移作用和最佳体外促迁移浓度。方法:随机取成年新西兰大白兔18只建立肩袖损伤模型,另取3只为空白对照。于造模后3,5,7,14,21,28 d各处死3只并处死空白组兔,取腱骨连接处组织保存在-80℃冰箱。应用ELISA反应检测损伤后各时间点愈合处基质细胞衍生因子1表达。取幼兔股骨骨髓间充质干细胞分离培养鉴定,通过transwell实验验证基质细胞衍生因子1对干细胞的促迁移作用效果及体外促迁移最佳浓度,将培养到P3代的干细胞与Brdu共培养后注入兔耳缘静脉,通过免疫组化染色验证干细胞是否迁移至损伤处。结果与结论:①基质细胞衍生因子1在肩袖腱骨愈合过程呈双峰表达,于伤后3 d明显增高(P<0.01)随后下降,于伤后5 d达最低,后再次升高于伤后14 d达峰值(P<0.01),然后下降;②细胞免疫组化染色可见标记有Brdu的干细胞确有迁移至损伤处;③transwell实验结果表明60-80 ng/mL的基质细胞衍生因子1对干细胞促迁移效果最好,而200 ng/mL浓度反而会起到抑制迁移作用;④基质细胞衍生因子1参与了肩袖腱骨愈合的炎症反应期和增殖期的愈合过程,其作用机制可能为通过促进干细胞迁移至损伤处并分化为各类细胞促进修复,并且基质细胞衍生因子1的促迁移作用存在于一定浓度范围,超出范围则可能起到抑制作用。

BACKGROUND:In recent years,some scholars in the field of tendon bone injury have attached stromal cell-derived factor 1 to tissue engineering scaffolds to promote tendon bone healing,and achieved good results.However,whether stromal cell-derived factor 1 promotes tendon bone healing mechanisms and participates in the repair of natural healing has not yet been defined.OBJECTIVE:To study the expression of stroma-cell derived factor 1 during tendon bone healing after rupture of the whole supraspinatus muscle of the rabbit rotator cuff and its migration effect and optimal in vitro migration promoting concentration on stem cells during tendon bone injury.METHODS:Totally 18 adult New Zealand rabbits were randomly selected to establish rotator cuff injury models,and an additional 3 rabbits were selected as blank controls.At 3,5,7,14,21,and 28 days after modeling,three rabbits were executed separately and the rabbits in the blank group were sacrificed.The tissues of tendon bone junction were taken and stored in a-80℃refrigerator.The expression of stromal cell-derived factor 1 was detected by ELISA at each time point after injury.Mesenchymal stem cells were isolated from the bone marrow of young rabbit femur,cultured,and identified.Transwell assay was performed to verify the migration-promoting effect of stromal cell-derived factor 1 on stem cells and the optimal migration-promoting concentration in vitro.The stem cells cultured to P3 were co-cultured with BrdU and injected into the rabbit ear marginal vein,and immunohistochemical staining was used to verify whether the stem cells migrated to the injury site.RESULTS AND CONCLUSION:(1)Stromal cell-derived factor 1 gene expression was bimodal during rotator cuff tendon bone healing.Stromal cell-derived factor 1 gene expression increased significantly at 3 days post-injury(P<0.01)and then decreased,reaching a minimum at 5 days post-injury.It increased again and reached a peak 14 days after injury(P<0.01)and then decreased.(2)Cell immunohistochemical staining displayed that stem cells labeled with BrdU did migrate to the injury site.(3)The results of the transwell experiment exhibited that 60-80 ng/mL stromal cell-derived factor 1 had the best effect on promoting migration of stem cells,while a concentration of 200 ng/mL inhibited migration.(4)Stromal cell-derived factor 1 is involved in the healing of rotator cuff tendon bone during the inflammatory response phase and the proliferation phase.The mechanism of action may be to promote the migration of stem cells to the injury and their differentiation into various types of cells to promote repair.In addition,the pro-migration effect of stromal cell-derived factor 1 exists at a range of concentrations,beyond which it may act as an inhibitor.