Alcohol-induced adipogenesis in a cloned cell line from bone marrow stroma

Quanjun Cui, MD, Yisheng Wang, MD, Kevin Mulhall, MD, Khaled Saleh, MD,
Gwo-Jaw Wang, MD, and Gary Balian, PhD, Presenting Author: Kevin Mulhall, MD

University of Virginia School of Medicine, Department of Orthopaedic Surgery
Box 800159, Charlottesville, VA 22908

Introduction: Alcohol can induce osteoporosis and osteonecrosis. Recent study demonstrated that alcohol contributed to abnormal lipid metabolism in cells in bone marrow but the mechanisms have not been defined. The purpose of this study was to evaluate the effect of alcohol on the differentiation of a pluripotential cell cloned from bone marrow.

Methods: The cells were maintained in culture and 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 using a phase-contrast microscope. Alkaline phosphatase activity was determined using a colorimetric assay. Gene expression of adipogenesis [422 (aP2), PPAR ?] and osteogenesis ( osteocalcin ) was evaluated using Northern blot technique and reverse transcription-polymerase chain reaction (RT-PCR). ANOVA was used for statistical analysis.

Results: The cells treated with ethanol started to accumulate triglyceride vesicles at Day 7, the number of adipocytes and the percentage of the area that contained the cells with fat vesicles increased significantly, 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 and without a significant increase in the expression of the fat cell specific gene, 422 (aP2), and PPAR ?, in cells treated with ethanol, suggesting that adipogenesis may occur at a point downstream in the fatty acid metabolism pathway.

Discussion: Alcohol induces bone marrow fatty changes in patients and in animal models contributing to osteoporosis and osteonecrosis. This study demonstrated that alcohol treatment decreased osteogenesis while enhancing adipogenesis by bone marrow stromal cells, which may be one of the mechanisms leading to osteoporosis and osteonecrosis. Inhibition of adipogenesis may lead to the prevention of the disease.

Clinical relevance: This is a novel finding that alcohol induces adipogenesis in a cloned bone marrow stromal cell. The results explain the clinical observation that there is increased adipogenesis in alcohol-induced osteoporosis and osteonecrosis.