中文摘要：

目的观察体外血清剥夺诱导大鼠骨髓间充质干细胞（BMSCs）凋亡及BMSCs凋亡过程中Smac基因表达变化,进一步探索BMSCs凋亡机制。方法用密度梯度离心和差异贴壁相结合法分离BMSCs,体外培养、扩增。流式细胞术对培养的BMSCs进行免疫表型鉴定。BMSCs体外血清剥夺培养0h（正常对照组）、24h、48h,用AnnexinⅤ-FITC和碘化丙啶（PI）双标记行流式细胞术凋亡检测。通过逆转录聚合酶链反应（RT-PCR）生成cDNA,以荧光定量PCR检测分析Smac mRNA的丰度。结果体外培养第5代BMSCs流式细胞术免疫表型鉴定结果符合BMSCs特点。与0h比较,血清剥夺24、48h后,BMSCs发生显著凋亡,各组比较有统计学差异（F=170.96P〈0.01）,且24h点早期凋亡百分率达到（32.99±2.52）%。同时荧光定量PCR检测显示24h点Smac mRNA表达与正常对照组相比显著升高（t=2.814P〈0.05）。结论血清剥夺能诱导BMSCs凋亡,被诱导凋亡的BMSCs中Smac基因转录增加。

英文摘要：

Objective To observe the apoptosis of rat bone mesenchymal stem cells（BMSCs） induced by serum-deprivation and to investigate its effects on Smac gene transcription.Methods Rat BMSCs were separated using density gradient centrifugation joined with diversity wall-adhesion method,and cultured,amplified in vitro,the immunophenotype of BMSCs was detected by flow cytometry,BMSCs were normally cultured or exposed to serum-deprivation for 24,48 h. Cells were stained with Annexin Ⅴ-FITC/PI and the percentage of apoptosis was analyzed by flow cytometry.And the levels of Smac mRNA were measured by fluorescent quantitation polymerase chain reaction （PCR）.Results Compared with normal control, apoptosis of rat BMSCs suffered serum-deprivation was obvious（F=170.96 P〈0.01）.And the percentage of early-stage apoptosis reached （32.99±2.52）% at 24 h.Treated with serum-deprivation for 24 h, the levels of Smac mRNA in BMSCs measured by fluorescent quantitation PCR was significantly higher than that of normal control（t=2.814 P〈0.05）.Conclusions The apoptosis of BMSCs could be significantly induced by serum-deprivation.Its mechanism may be related to the up-regulation of Smac mRNA.