锌对人脐带血间充质干细胞的细胞周期蛋白D2和细胞周期蛋白依赖性激酶4含量的影响

INFLUENCES OF ZINC ON CONCENTRATIONS OF CYCLIN D2 AND CYCLIN-DEPENDENT KINASE 4 OF HUMAN UMBILICAL CORD BLOOD-DRIVED MESENCHYMAL STEM CELLS

目的探讨锌对人脐带血间充质干细胞(human umbilical cord blood-drived mesenchymal stem cells,hUCBMSCs)细胞周期蛋白D2(cyclin D2)、细胞周期蛋白依赖性激酶4(cyclin-dependent kinase4,CDK4)、DNA和总蛋白含量的影响。方法采用密度梯度离心法分离培养hUCBMSCs。传代培养时将实验分为7组,对照组采用含15%FBS的DMEM培养基行传代培养,6个锌处理组于上述培养基中加入ZnSO4?7H2O,使锌终浓度分别为0.5、1.5、2.5、3.5、4.5、5.5mg/L。用流式细胞仪检测第3代hUCBMSCs表面抗原CD29、CD34、CD44和CD45;MTT法检测细胞活性,筛选最佳锌浓度组定为实验组。取实验组和对照组第3代hUCBMSCs绘制细胞生长曲线,流式细胞仪检测细胞DNA含量和增殖周期,Western blot检测总蛋白及cyclin D2和CDK4含量。结果 hUCBMSCs表面抗原CD29和CD44阳性表达率均>70%。MTT检测示,2.5mg/L浓度组细胞活性最高,定为实验组。培养7、14、28d,实验组hUCBMSCs的总蛋白含量、DNA含量、cyclin D2和CDK4含量均明显高于对照组(P<0.01);细胞增殖指数、S期细胞百分比均较对照组明显升高(P<0.01)。结论 0.5～4.5mg/L浓度的锌能增强hUCBMSCs活性,其中2.5mg/L为最佳浓度,可促进hUCBMSCs增殖和DNA复制,增加细胞cyclin D2、CDK4和总蛋白含量。

Objective To explore effects of zinc on the contents of cyclin D2, cyclin-dependent kinase 4 （CDK4）, and their DNA and total cellular protein in human umbilical cord blood-drived mesenchymal stem cells （hUCBMSCs）. Methods hUCBMSCs were isolated and cultured by density gradient centrifugation adherence method in vitro. At the serial subcultivation, the hUCBMSCs were randomly divided into 7 groups. In control group, hUCBMSCs were cultured with DMEM medium （containing 15%FBS）. In treatment groups, hUCBMSCs were cultured with DMEM medium （containing 15%FBS plus ZnSO 4 ？7H 2 O）. The final concentrations of zinc were 0.5, 1.5, 2.5, 3.5, 4.5, and 5.5 mg/L, respectively. The cellular surface antigens of CD29, CD34, CD44, and CD45 at the 3rd generation of hUCBMSCs were detected by flow cytometry. MTT assay was used to detect cell activity of the 3rd generation of hUCBMSCs. The optimum concentration of zinc was selected by the results of MTT as experimental group. The cell growth curves of experimental group and control group were drown by counting cell. The cell surface antigen, reproductive cycle, and DNA content were detected by flow cytometry motheds. The contents of cyclin D2 and CDK4 were detected by Western blot method. Results The positive expression rates of CD29 and CD44 were more than 70% in hUCBMSCs. The cell activity of 2.5 mg/L treatment group was superior to other treatment groups, as experimental group. At 7, 14, and 28 days, the contents of DNA, total cellular protein, cyclin D2, and CDK4 of hUCBMSCs were significantly higher in experimental group than those in control group （P〈0.01）. The percentage of hUCBMSCs at S stage and proliferation index in experimental group were also significantly higher than those in control group （P〈0.01）. Conclusion Zinc （0.5-4.5 mg/L） has the promoting effect on the hUCBMSCs activity, and 2.5 mg/L is the optimal concentration. Zinc （2.5 mg/L） can accelerate the proliferation and DNA reproduction of hUCBMSCs and increase the contents of cyclin D2 , CDK4, and cellular total protein.