低氧微环境促进人嗅黏膜间充质干细胞的增殖及其机制

摘要

BACKGROUND: Human olfactory mucosa mesenchymal stem cells (hOM-MSCs) not only have the basic characteristics of mesenchymal stem cells, but also originate from the ectoderm and are prone to differentiate into neurons, which are a kind of ideal seed cells for nerve repair and regeneration. Cells are conventionally cultured in about 21% in vitro, while only 3%-9% oxygen is found in the human body and tissue space. There is still no report on the effect of hypoxia on the proliferation and activity of hOM-MSCs.OBJECTIVE: To explore whether hypoxic microenvironment can promote hOM-MSCs proliferation and activity and the related mechanism. METHODS: hOM-MSCs were isolated, cultured and identified by flow cytometry and immunofluorescence. The passage 4 hOM-MSCs were divided into three groups: 21% O2 group, 3% O2 group and 3% O2+20 μmol/L YC-1 (HIF-1α inhibitors) group. Proliferation and apoptosis of hOM-MSCs was detected by flow cytometry after 72 hours of culture. The proliferating cell nuclear antigen protein expression was detected by western blot. The mRNA and protein expression of HIF-1α and TWIST were detected by Q-PCR and western blot. RESULTS AND CONCLUSION: The purity of hOM-MSCs was up to 97%, as defined by flow cytometry. The proliferation index of 3% O2 group was higher than the 21% O2 group (P < 0.05), and cell survival and apoptosis ratio (apoptotic cells included mechanical death + early apoptosis + late apoptosis) between the two groups had no significant difference (P > 0.05). Western blot results showed that the proliferating cell nuclear antigen protein expression in the 3% O2 group was significantly higher than that in the other groups (P < 0.05). The HIF-1α and TWIST expressions at mRNA and protein levels in the 3% O2 group were significantly higher than those in the other groups (P < 0.05). To conclude, hypoxic microenvironment can promote the hOM-MSCs proliferation and has no effect on the apoptosis, and the HIF-TWIST signal pathway plays an important role in this progress.%背景:人嗅黏膜间充质干细胞不仅具有一般间充质干细胞的基本特征,因其来源于外胚层,还能更多地向神经元方向分化,是一种用于神经损伤修复与再生的理想种子细胞.常规细胞体外培养的氧气体积分数约为21%,而人体正常组织和组织间隙中的氧气体积分数为3%-9%.低氧对人嗅黏膜间充质干细胞增殖及活性的影响尚未见报道.目的:探讨低氧微环境对人嗅黏膜间充质干细胞增殖、活性的影响及其相关机制.方法:分离培养人嗅黏膜间充质干细胞,应用流式细胞学和免疫荧光方法分别进行鉴定;实验将第4代人嗅黏膜间充质干细胞分成3组:体积分数为21%O2组(常氧组)、体积分数为3%O2组(低氧组)、体积分数为3%O2+20μmol/L YC-1(HIF-1α抑制剂)组(抑制剂组),干预72 h后采用流式细胞技术检测各组细胞的细胞周期和细胞凋亡情况;采用Western blot方法检测增殖细胞核抗原的蛋白表达;采用Q-PCR及Western Blot分别检测HIF-1α和TWIST的mRNA及蛋白表达.结果与结论:①分离培养出了人嗅黏膜间充质干细胞,第4代人嗅黏膜间充质干细胞的纯度达97%以上;②低氧组比常氧组的增殖系数大(P<0.05),且两组间的存活细胞及总体的凋亡细胞(机械死亡+早期凋亡+晚期凋亡)比例差异无显著性意义(P>0.05);③低氧组的增殖细胞核抗原蛋白表达显著增高,与常氧组和抑制剂组比较差异有显著性意义(P<0.05);④低氧组中HIF-1α和TWIST mRNA和蛋白表达显著上调,与常氧组和抑制剂组比较差异有显著性意义(P<0.05);⑤低氧微环境能促进人嗅黏膜间充质干细胞的增殖而对其细胞活性无明显影响,且此过程与人嗅黏膜间充质干细胞内HIF-TWIST信号通路被激活有关.