LAUSR

OBJECTIVE In multiple myeloma (MM), stimulation of osteoclasts and bone marrow (BM) lesions lead to hypercalcemia, renal failure, and anemia. Co-culture of the myeloma cells in both hypocalcemia and hypercalcemia concentrations with bone marrow-mesenchymal stem cells were evaluated. MATERIALS AND METHODS Viability and survival of myeloma cells were assessed by microculture tetrazolium test and flow cytometric assays. Mesenchymal stem cells (MSCs) were extracted from normal and myeloma patients and were co-cultured with myeloma cells. RESULTS Myeloma cells showed less survival in both hypocalcaemia and hypercalcemia conditions (P <.01). The paracrine and juxtacrine conditions of demineralized bone matrix-induced hypercalcemia increased the proliferation and survival of the cells (P <.05). Unlike myeloma MSCs, normal MSCs reduced the survival of and induced apoptosis in myeloma cells (P <.1). CONCLUSION Normal healthy-MSCs do not protect myeloma cells, but inhibit them. However, increasing the ratio of myeloma cells to MSCs reduces their inhibitory effects of MSCs and leads to their myelomatous transformation.