Alkahtani Ahmed, Alkahtany Sarah M, Anil Sukumaran
Associate Professor, Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Kingdom of Saudi Arabia, e-mail:
Lecturer, Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Kingdom of Saudi Arabia.
J Contemp Dent Pract. 2014 Jul 1;15(4):473-81. doi: 10.5005/jp-journals-10024-1565.
To evaluate and compare the cytotoxicity of various concentrations of sodium hypochlorite on immortalized human bone marrow mesenchymal stem cells (MSCs).
The 5.25 percent sodium hypochlo-rite (NaOCl) at concentrations of 0.5, 0.1, 0.025, 0.0125, and 0.005 mg/ml were used to assess the cytotoxic effect on MSCs. Immortalized human bone marrow mesenchymal stem cells (hTERT-MSCs) were exposed to NaOCl at 5 different concentrations. Cell viability was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and alamarBlue assays. The cell morphology changes were assessed with scanning electron microscopy (SEM) after exposure to 2, 4, and 24 hour incubation. The ethidium bromide/acridine orange (EB/ AO) fuorescent stain was applied to the cells in the 8-chamber slides after they were incubated with the testing agents for 2 and 4 hours to detect live and dead cells. The observations were quantitatively and qualitatively analyzed.
The cell viability study using MTT assay and AB assay showed significant reduction with varying concentration at 2 and 4 hours incubation period. The cell viability decreased with the higher percentage of NaOCl. The exposure time also revealed an inverse relation to the cell viability. The SEM analysis showed reduction in the number of cells and morphological alterations with 0.5 mg/ml at 2 and 4 hours compared to 0.025 mg/ml NaOCl. Destruction of the cells with structural alterations and lysis was evident under fuorescence microscope when the cells were exposed to 0.5 mg/ml NaOCl.
Within the limitations of this in vitro study it can be concluded that NaOCl is toxic to the human bone marrow MSCs. The cell lysis was evident with higher concentration of sodium hypochlorite. From the observations, it can be concluded that a lower concentration of NaOCl may be used as endodontic irrigant due to its cytotoxic properties. Further studies are mandatory to evolve a consensus on the optimal concentration of sodium hypochlorite to be used as endodontic irrigant.
评估并比较不同浓度次氯酸钠对永生化人骨髓间充质干细胞（MSCs）的细胞毒性。
使用浓度为0.5、0.1、0.025、0.0125和0.005mg/ml的5.25%次氯酸钠（NaOCl）评估其对MSCs的细胞毒性作用。将永生化人骨髓间充质干细胞（hTERT-MSCs）暴露于5种不同浓度的NaOCl中。通过3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐（MTT）和alamarBlue检测评估细胞活力。在暴露2、4和24小时后，用扫描电子显微镜（SEM）评估细胞形态变化。在用测试剂孵育2和4小时后，将溴化乙锭/吖啶橙（EB/AO）荧光染色应用于8孔载玻片上的细胞，以检测活细胞和死细胞。对观察结果进行定量和定性分析。
使用MTT检测和AB检测的细胞活力研究表明，在孵育2和4小时时，不同浓度下细胞活力均显著降低。NaOCl浓度越高，细胞活力越低。暴露时间也与细胞活力呈反比关系。SEM分析显示，与0.025mg/ml NaOCl相比，在2和4小时时，0.5mg/ml的细胞数量减少且形态改变。当细胞暴露于0.5mg/ml NaOCl时，在荧光显微镜下可见细胞结构改变和裂解。
在本体外研究的局限性内，可以得出结论，NaOCl对人骨髓MSCs有毒性。次氯酸钠浓度越高，细胞裂解越明显。从观察结果可以得出结论，由于其细胞毒性特性，较低浓度的NaOCl可作为根管冲洗剂。需要进一步研究以就用作根管冲洗剂的次氯酸钠最佳浓度达成共识。
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