Effects of Glucocorticoid on Apoptosis of Human Bone Marrow Osteogenic Stromal Cells / 대한내분비학회지

ABSTRACT

BACKGROUND: Osteoporosis is one of the most serious side effects of long-term glucocorticoid therapy, but the mechanism of glucocorticoid-induced bone loss remains poorly defined. Glucocorticoid induces decreased bone formation and death of isolated segments of bone (osteonecrosis) suggesting that glucocorticoid excess may affect the birth or death rate of bone cells and thereby reduce their numbers. It has been known that reduction in bone formation is due to reduced proliferation in osteoblast precursor cells and reduced matrix synthesis in mature osteoblast. Here, we present evidence for dexamethasone-induced apoptosis on human bone marrow stromal cells (hBMSC). To understand the mechanism of glucocorticoid-induced osteoporosis, we investigated the effects of glucocorticoid on primary cultured hBMSC. METHEODS Treatment with dexamethasone at the concentration of 10-9 M for 3~5 days significantly decreased cleavage tetrazolium salt WST-1 level/concentration by mitochondrial dehydrogenase in viable cells. Greater decrease was observed with higher concentration of dexamethasone (10-7 M, and 10-5 M). Apoptosis was measured by annexin V binding/propidium iodide using fluorescence-activated cell sorter (FACS) analysis and nuclear morphology stained with the fluorescence dye, Hoechst 33342. RESULTS: The level/concentration of apoptotic hBMSC (annexin V positive / PI negative) was increased with 10-9 M dexamethasone (1.2% to 5.3%) and further increased with 10-7 M, and 10-5 M concentration (11.7% and 12.5%, respectively). The same result was observed with Hoechst 33342 staining. CONCLUSION: These results indicate that glucocorticoid induces apoptosis on osteoblast precursor cell, hBMSC, and may contribute to decrease bone formation