State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.
Br J Pharmacol. 2010 Dec;161(7):1542-52. doi: 10.1111/j.1476-5381.2010.00998.x.
Caffeine is consumed extensively in Europe and North America. As a risk factor for osteoporosis, epidemiological studies have observed that caffeine can decrease bone mineral density, adversely affect calcium absorption and increase the risk of bone fracture. However, the exact mechanisms have not been fully investigated. Here, we examined the effects of caffeine on the viability and osteogenesis of rat bone marrow-derived mesenchymal stromal cells (rBMSCs).
Cell viability, apoptosis and necrosis were quantified using thymidine incorporation and flow cytometry. Sequential gene expressions in osteogenic process were measured by real-time PCR. cAMP, alkaline phosphatase and osteocalcin were assessed by immunoassay, spectrophotometry and radioimmunoassay, respectively. Mineralization was determined by calcium deposition.
After treating BMSCs with high caffeine concentrations (0.1-1mM), their viability decreased in a concentration-dependent manner. This cell death was primarily due to necrosis and, to a small extent, apoptosis. Genes and protein sequentially expressed in osteogenesis, including Cbfa1/Runx2, collagen I, alkaline phosphatase and its protein, were significantly downregulated except for osteocalcin and its protein. Moreover, caffeine inhibited calcium deposition in a concentration- and time-dependent manner, but increased intracellular cAMP in a concentration-dependent manner.
By suppressing the commitment of BMSCs to the osteogenic lineage and selectively inhibiting gene expression, caffeine downregulated some important events in osteogenesis and ultimately affected bone mass.
咖啡因在欧洲和北美被广泛消费。作为骨质疏松症的一个风险因素，流行病学研究观察到咖啡因可以降低骨密度，不良影响钙吸收，并增加骨折的风险。然而，确切的机制尚未被充分研究。在这里，我们研究了咖啡因对大鼠骨髓间充质基质细胞（rBMSCs）活力和成骨作用的影响。
使用胸苷掺入和流式细胞术定量细胞活力、细胞凋亡和细胞坏死。通过实时 PCR 测量成骨过程中的连续基因表达。通过免疫测定、分光光度法和放射免疫测定分别评估 cAMP、碱性磷酸酶和骨钙素。通过钙沉积来确定矿化。
用高浓度咖啡因（0.1-1mM）处理 BMSCs 后，其活力呈浓度依赖性下降。这种细胞死亡主要是由于坏死，在较小程度上是由于凋亡。成骨过程中顺序表达的基因和蛋白质，包括 Cbfa1/Runx2、胶原蛋白 I、碱性磷酸酶及其蛋白，除了骨钙素及其蛋白外，均显著下调。此外，咖啡因呈浓度和时间依赖性地抑制钙沉积，但呈浓度依赖性地增加细胞内 cAMP。
通过抑制 BMSCs 向成骨谱系的定向分化，并选择性地抑制基因表达，咖啡因下调了成骨过程中的一些重要事件，并最终影响了骨量。
