LABORATORY AND ANIMAL STUDIES

Effects of Dexamethasone and Lovastatin on the Expression of BMP2 in Bone Marrow Stroma Cells Cultured from Patients with Osteonecrosis
GJ Wang, JK Chang, ML Ho, CH Yeh
Orthopaedic Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan

Our previous study found that glucocorticoid shifted the properties of osteogenesis to adipogenesis in murine marrow stem cells. These effects may be one of the important mechanisms of the pathogenesis of osteonecrosis. Statins prevented these steroid effects. In this study, we investigated the effects of dexamethasone and lovastatin on the expressions of bone morphogenetic protein-2 (BMP2) in the bone marrow stroma cells cultured from osteonecrotic patients. Bone marrow fluid aspiration from iliac crest was performed in osteonecrosis (ON) and non-ON patients after surgical treatment for the hip disorder. The mean age of the patients were 58.7 in ON group and 62.9 in non-ON group. Nucleated stroma cells were isolated from bone marrow fluid by percol separation. The third passage cultures were used for experiments. Drug treatments for cultures were dexamethasone (10-7M), lovastatin (10-6 M) and dexamethasone plus lovastatin for 4 days. BMP-2 mRNA expressions were evaluated by RT-PCR. Different responses to drugs between ON group and non-ON group were compared. We found that the bone marrow stroma cells of ON patients have more susceptible to the suppressive effect of dexamethasone on BMP2 expression. Lovastatin stimulated the osteogenesis and reversed the steroid suppressive effect in bone marrow stroma cells in non-ON cases. However, this reverse effect is mild in ON cases.