中文摘要：

目的观察氧化低密度脂蛋白（ox－LDL）对造血干细胞（HSCs）细胞周期调控基因p16、p21、CDK2、CDK4及细胞周期蛋白（cyclinD）表达的影响，探讨ox-LDL诱导HSCs衰老的可能分子机制。方法采用免疫磁性分选法分离纯化小鼠Sca-1＋HSCs，并与ox-LDL共培养，通过衰老相关β-半乳糖苷酶（SA-β-Gal）染色检测衰老HSCs，四唑氮盐（MTS）比色法与多向造血祖细胞（CFU-Mix）混合集落培养检测HSCs自我更新能力和多向分化潜能，流式细胞术分析细胞周期分布，荧光定量PCR及Westernblotting检测HSCsp16、p21、CDK2、CDK4及cyclinD表达。结果与对照组比较，ox-LDL能增加HSCsSA-β-Gal染色阳性细胞率；促进HSCs停滞于G1期，G0／G1期细胞增多、S期细胞减少，减弱HSCs自我更新与多向分化能力；ox-LDL能上调HSCsp16和p21mRNA及蛋白表达水平，下调CDK4及cyclinD蛋白表达，而对CDK2蛋白表达无影响。结论ox-LDL能通过上调p16、p21表达及下调CDK4、cyclinD表达，在体外促进HSCs衰老。

英文摘要：

Objective To observe the effect of oxidation low density lipoprotein on aging of hematopoietic stem cells （HSCs） and to reveal the underlying mechanisms that ox-LDL induce the aging of HSCs. Method Mouse HSCs were isolated by magnetic cell sorting with Sea-1 staining. Sea-1 ＋ HSCs were cultured with ox-LDL. Senescence-associated β-galactos idase （SAβ-Gal） staining was used to identify aging HSCs. The capacity of self-renewal of HSCs was evaluated by MTS assay. CFU-Mix cultivation was used to evaluate the potency of differentiation in HSCs. Cell cycles were detected by flow cytometry. The expressions of p16, p21, CDK4 and cyelinD were determined by real-time quantitative PCR （ qRT- PCR） and Western blotting analysis. Results Exogenous ox-LDL significantly increased the number of SAβ-Gal staining postive in HSCs, promoted HSCs to arrest at S stage, elevated the ratio of G0/G1 stage , decreased the ratio of S stage and the number of CFU-Mix, and inhibited the proliferation of HSCs compared to HSCs without ox-LDL treatment group. ox-LDL remarkedly upregulated the expression of p16 and p21 in mRNA and protein levels, decreased the protein expression of CDK4 and cyclinD. There was no significant difference in the protein expression of CDK2 in HSCs. Conclusion ox-LDL may induce mice HSCs aging through upregulating the expressions of p16 and p21, and downregulating CDK4 and eyclinD expressions.