Cui Quanjun, Wang Yisheng, Saleh Khaled J, Wang Gwo-Jaw, Balian Gary
Department of Orthopaedic Surgery, University of Virginia, School of Medicine, Box 800159, Charlottesville, VA 22908, USA.
J Bone Joint Surg Am. 2006 Nov;88 Suppl 3:148-54. doi: 10.2106/JBJS.F.00534.
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.
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.
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.
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.
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.
在患者和动物模型中，酒精已被证明与骨质疏松症和骨坏死有关。最近的研究表明，酒精会导致骨髓基质细胞脂质代谢异常，但其机制尚未明确。本研究的目的是评估酒精对从骨髓克隆的干细胞分化的影响。
用递增浓度的乙醇（0.09、0.15和0.21mol/L）处理D1细胞（从BALB/c小鼠克隆的骨髓干细胞），或不使用酒精作为对照。使用相差显微镜监测细胞的形态特征。使用比色法测定碱性磷酸酶活性。使用Northern印迹和逆转录-聚合酶链反应测定法评估作为脂肪生成指标的基因[422(aP2)、PPARγ]和成骨指标的基因（骨钙素）的表达。
用乙醇处理的细胞在第7天开始积累甘油三酯囊泡。脂肪细胞数量和含有脂肪囊泡的细胞所占面积百分比显著增加（p<0.05），并且碱性磷酸酶活性水平随着乙醇暴露时间延长和浓度升高而降低。基因表达分析显示骨钙素表达降低。在用乙醇处理的细胞中，脂肪细胞特异性基因422(aP2)或PPARγ的表达均未显著增加，这表明脂肪生成可能发生在脂肪酸代谢途径的下游某个点。
酒精处理会降低克隆的骨髓干细胞的成骨能力，同时增强其脂肪生成能力，表明酗酒可能是导致骨质疏松症和骨坏死的机制之一。这一发现解释了酒精性骨质疏松症和骨坏死中脂肪生成增加的临床观察结果。
抑制骨髓脂肪生成并同时增强成骨作用可能为预防或治疗骨坏死和骨质疏松症提供一种新方法。
