Effect Of Myeloma Cells On RANKL Expressions Of Normal Osteocytes Measured By Using A Fluid Chamber Method

Objective: To establish a simulation device of flow fluid chamber on RANKL expression of osteocytes in myeloma cells and to determine the affect of myeloma cells on normal bone cells.Methods: Myeloma cell line U266 and mouse osteocytes cell line Y4 were maintained in vitro.Morphological features were examined by microscopy for the number and morphology of cells.RANKL levels were measured by Elisa assay of two kinds of cell-culture medium from myeloma cells and osteocyte cells.Culture medium was collected,and divided them into two groups,group A(Y4 cell medium)and group B(U266 cell medium),each group had 6 subgroups;the cells were then implanted into the FLOW FLUID CHAMBER.Results: Microscopic examination showed Y4 cells cultured with U266 medium decreased in number and underwent pleomorphic changes as compared with those cultured with Y4 cell-culture medium.The number of cells in B group was higher than that of without flow after 2 hours`flow in flow fluid chamber(P<0.05);RANKL level in Group A was found to be lower than that of group B.Flow mode showed effect on reduced RANKL than “no flow” mode(P<0.05).Osteocalcin differentiation TRAP staining results were positive,B group differentiation than the number of A group(P<0.05),The number of osteoclasts in the supernatant was lower than that in the no flow mode 。Conclusion: Myeloma bone disease is related to role of myeloma cells in inhibiting normal osteocyte cells through RANKL pathway.By myeloma cells affected,osteocytes can be highly expressed RANKL,stimulate osteoclast differentiation increased Flow dynamics may result in a decrease in the expression of RANKL,thereby reducing bone damage in myeloma bone disease.