低氧对人牙周膜细胞增殖、细胞周期及分化潜能的影响

A preliminary study on effects of hypoxia on the proliferation,cell cycle and differentiation of human periodontal ligament cells

目的：研究低氧对人牙周膜细胞（hPDLC）增殖、细胞周期以及干细胞表面标志物（STRO-1和CD146）表达水平的影响。方法采用组织块法体外分离培养hPDLC；取第3~5代细胞分别在常氧和低氧（1.5%~2.0% O2）条件下培养12、24、36、48 h,采用MTT法检测低氧对细胞增殖的影响；并通过流式细胞术检测低氧条件下细胞周期的变化以及细胞表面STRO-1和CD146表达水平的变化。结果两组细胞增殖率随时间延长而增加,12和24 h低氧组细胞增殖率比常氧组稍高,差别无统计学意义。36和48 h低氧组增殖活性较常氧组降低,差异有统计学意义（t36 h=3.538, P36 h=0.024；t48 h=5.349,P48 h=0.006）；12 h低氧组细胞的增殖指数（PI）比常氧组低,24和36 h低氧组细胞PI比常氧组高,但差异均无统计学意义,48 h低氧组细胞PI比常氧组高,差异有统计学意义（t48 h=-5.768,P48 h=0.004）；4个时间点低氧组细胞STRO-1和CD146的表达水平与常氧组比较差异无统计学意义。结论低氧抑制hPDLC的增殖,但促进hPDLC DNA合成；hPDLC在低氧条件下能保持其分化潜能。

Objective To investigate the biological effect of hypoxia on the proliferation, cell cycle and expression level of stem cell marker （STRO-1 and CD146） of human periodontal ligament cells （hPDLCs）. Methods HPDLCs were isolated and cultured by the method of tissue lump. Third to fifth passage of HPDLCs were cultured at the condition of hypoxia （1.5% ~ 2.0% O2） and normaxia for 12, 24, 36 and 48 h, and MTT was used to evaluate the proliferation of HPDLCs; cell cycle and expression level of stem cell marker STRO-1 and CD146 was detected by flow cytometry. Results Both of hypoxia and normoxia groups of HPDLCs proliferation gradually increased as time went on. Proliferation rate of HPDLCs was slight higher in the hypoxia groups than in the normoxia groups at 12 or 24 h, and both were not significantly statistical difference. At 36 h or 48 h of incubation, proliferation rate of HPDLCs in hypoxia groups were lower than in normoxia groups （t36 h=3.538,P36 h=0.024;t48 h=5.349,P48 h=0.006）; Proliferative index （PI） of HPDLCs in hypoxia group was slightly lower than in normoxia group at 12 h of incubation; PI of HPDLCs in hypoxia group was slightly higher than in normoxia group at 24 h or 36 h of incubation, but both were not statistically difference. PI of hPDLCs in hypoxia group was significantly higher than in normoxia group at 48 h of incubation （t48 h=-5.768,P48 h=0.004）. The expression level of STRO-1 and CD146 were not significantly statistical difference in both of hypoxia group and normoxia group at four tested time point. Conclusions Hypoxia inhibits the＆amp;nbsp;proliferation of hPDLCs, but promote the DNA synthesis of hPDLCs. HPDLCs can maintain differentiation potential under hypoxic conditions.