P>Objective To study the effects of low dose sodium arsenite to human bone marrow mesenchymal stem cells(hBMSCs) differentiation during establishing of arsenic-resistant cell model. Methods hBMSCs were prepared in conventional method and continuously exposed to 1μmol/L sodium arsenite for ≥12weeks EM>in vitro/EM>. Forty-eight hours acute arsenite toxicity test was drived to assay if the cells acquired arsenic-resistance. The proliferation capacity of CAsE-hBMSCs was observed by the rate of colony formation.The expression of Oct-4 in CAsE-hBMSCs was assayed by RT-PCR and immunocytochemistry. The expression of ABCG2 in CAsE-hBMSCs was analyzed by RT-PCR. Results hBMSCs continuously exposed to 1μmol/L sodium asenite for ≥12 weeks exhibited dramatic resistance to acute arsenite toxicity. The LCSUB>50/SUB> for acute arsenite exposure in CAsE-hBMSCs was 35.59μmol/L versus 18.04μmol/L in control cells. Compared to control cells, the CAsE-hBMSCs didn’t show malignant proliferation ability. Expression of Oct-4 gene was positive in 4th, 18th passage hBMSCs and the hBMSCs induced by arsenite for 4 weeks but negative in CAsE-hBMSCs. The expression of Oct-4 protein was positive and weakly positive in 4th passage hBMSCs and CAsE-hBMSCs respectively, and the positive granules of Oct-4 distributed in cytoplasm. The expression of ABCG2 gene in CAsE-hBMSCs was obviously lower than that in control cells (EM>P/EM><0.001). Conclusion Human b