Objective:In our previous study,tumor necrosis factor (TNF)-α was showed to enhance the osteogenic differentiation of bone marrow derived mesenchymal stem cells (MSC). In this study,we aimed to investigate what effects of TNF-α pre-treated bone marrow MSC on myeloma cells when they were in vitro co-cultured. Methods:Normal bone marrow MSC was treated with TNF-α for once (T+1 cohort ) or once a day for seven days (T+7 cohort),then the TNF-α pre-treated MSC was directly co-cultured with myeloma cell line H929 cells for four days. At the end of co-culture,H929 cells were harvested and tested for the number of colony-forming units (CFU),mRNA levels of POU5F1,SOX2 and NANOG and miroRNA levels of miRNA-15a/16 by real-time PCR. The results from T+7 cohort were statistically compared with both T+1 and control cohorts. Results:TNF-α treatment did not cause any evidently morphological alterations on bone marrow MSCs. When compared with the control and T+1 cohort,our data showed the number of CFU in H929 was statistically decreased in T+7 cohort,the mRAN levels of POU5F1 and SOX2 were statistically down-regulated in T+7 cohort as well. However,the microRAN levels of both miRNA-15a and miRNA-16 were statistically up-regulated. Conclusion:Multiple TNF-α pre-treated bone marrow MSC was showed to has inhibitory effects on MM cells.