镉致成骨细胞增殖、分化及矿化损伤的预后效应

Prognosis of Biological Functions of Osteoblast after Exposure to Cadmium

[目的]探讨镉染毒和染毒中止后成骨细胞增殖、分化及矿化等生物学功能的改变。[方法]采用混合酶消化法,分离SD大鼠颅盖骨成骨细胞,在5%CO_2、37℃条件下培养24h后,持续镉染毒组以不同浓度的氯化镉(0～2.000μmol/L)持续染毒72h;间断镉染毒组以同样浓度的氯化镉染毒48h后,更换成无镉培养液继续培养24h,以噻唑蓝(MTT)法测定细胞增殖能力改变,用对硝基苯磷酸二钠盐(PNPP)偶氮法检测碱性磷酸酶(ALP)活性。同时,成骨细胞培养7d后,以0.500μmol/L氯化镉持续作用3～13d,然后分别停止作用10、8、6、0d,采用茜素红S进行矿化结节染色并计算面积以观察镉暴露中止后成骨细胞矿化能力损伤的恢复情况。[结果]氯化镉可明显抑制成骨细胞增殖、ALP活性及矿化能力。间断镉染毒组在停止作用24 h后,成骨细胞的增殖、分化仍然明显低于对照组(P<0.05),与持续作用组比较没有明显改善。同样,间断镉染毒组在停止作用不同时间后,成骨细胞矿化结节数量和面积仍然明显低于对照组(P<0.05),与持续作用组相比没有明显恢复。[结论]镉暴露中止一定时间后,镉对成骨细胞的影响作用仍明显存在,表现为对成骨细胞增殖、分化及矿化能力的持续抑制。

[ Objective ] To investigate the effects of cadmium on proliferation, differentiation and mineralization in osteoblasts, and their evolution after cessation of exposure. [ Methods ] The osteoblast cells were harvested by sequential enzyme digestion from ealvaria of SD rats and then cultured. One group was treated with CdCl2 （ 0-2.000 μmol/L ） continually for 72 h; another group was exposed to cadmium （ 0-2.000 μmnol/L ）for 48 h, then shifted to culture with a medium free of cadmium for 24 h, then the proliferation was analyzed by methyhhiazolyldiphenyl-tetrazolium bromide （ MTT ） method, and the alkaline phosphatase （ ALP ） activity was assayed by p-nitrophenyl phosphate （ PNPP ）method. The effects of cadmium chloride （ 0.500 μmol/L ）exposure lasting for 3-13 d on osteoblast mineralization and evolution were also observed on 10 d, 8 d, 6 d, and 0 d after cessation of exposure. I Results Cadmium could inhibit the proliferation, ALP activity and mineralization of osteoblast ceils. The proliferation, differentiation and mineralization ability of osteoblasts after cessation of cadmium exposure were still significantly lower than that of the control, P 〈 0.05. No obvious improvement in proliferation, differentiation and mineralization were observed in osteoblasts after the cessation of cadmium exposure compared to that in the continuous exposure group. [ Conclusion ] Effects of cadmium on osteoblasts in the form of inhibition on proliferation, differentiation and mineralization remain even the exposure is blocked.