Alcohol-induced adipogenesis in a cloned bone-marrow stem cell.
BACKGROUND
Alcohol has been shown to be associated with osteoporosis and osteonecrosis in patients and in animal models. Recent studies have demonstrated that alcohol contributes to abnormal lipid metabolism in the stromal cells of bone marrow, but the mechanisms have not been defined. The purpose of this study was to evaluate the effects of alcohol on the differentiation of a stem cell that was cloned from bone marrow.


METHODS
D1 cells (cloned bone-marrow stem cells from a BALB/c mouse) were treated either with increasing concentrations of ethanol (0.09, 0.15, and 0.21 mol/L) or without alcohol to serve as controls. Morphologic features of the cells were monitored with use of a phase-contrast microscope. Alkaline phosphatase activity was determined with use of a colorimetric assay. The expression of genes that are indicators of adipogenesis [422(aP2), PPARgamma] and osteogenesis (osteocalcin) was evaluated using Northern blot and reverse transcription-polymerase chain reaction assays.


RESULTS
The cells treated with ethanol started to accumulate triglyceride vesicles at day seven. The number of adipocytes and the percentage of the area that contained the cells with fat vesicles increased significantly (p < 0.05), and the level of alkaline phosphatase activity diminished with longer durations of exposure to ethanol and with higher concentrations. Analysis of gene expression showed diminished expression of osteocalcin. This occurred without a significant increase in the expression of either the fat-cell-specific gene 422(aP2) or PPARgamma in cells treated with ethanol, suggesting that adipogenesis may occur at a point downstream in the fatty-acid-metabolism pathway.


CONCLUSIONS
Alcohol treatment decreases osteogenesis while enhancing adipogenesis in a cloned bone-marrow stem cell, indicating that alcohol abuse may be one of the mechanisms leading to osteoporosis and osteonecrosis. This finding explains the clinical observation that there is increased adipogenesis in alcohol-induced osteoporosis and osteonecrosis.


CONCLUSIONS
The inhibition of bone-marrow adipogenesis and the concomitant enhancement of osteogenesis may provide a novel approach to the prevention or treatment of osteonecrosis and osteoporosis.
Cui
Quanjun
Q
Department of Orthopaedic Surgery, University of Virginia, School of Medicine, Box 800159, Charlottesville, VA 22908, USA. qc4q@hscmail.mcc.virginia.edu
Wang
Yisheng
Y
Saleh
Khaled J
KJ
Wang
Gwo-Jaw
GJ
Balian
Gary
G
D050156:Adipogenesis / Q000187:drug effects*; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D018929:Cell Culture Techniques; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D002999:Clone Cells; D000431:Ethanol / Q000494:pharmacology*; D050556:Fatty Acid-Binding Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects; D047495:PPAR gamma / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
D002492:Central Nervous System Depressants; C493411:Fabp4 protein, mouse; D050556:Fatty Acid-Binding Proteins; D047495:PPAR gamma; D012333:RNA, Messenger; D015675:Osteocalcin; D000431:Ethanol