Effect of Alendronate on the metabolism of cartilaginous and disc cells in vitro

双膦酸盐已广泛用于治疗骨质疏松症。最近，阿仑膦酸钠可能具有软骨保护作用，可能与骨关节炎有关。聚集蛋白聚糖浓度福尔斯在软骨和椎间盘退变期间显著下降，具有不幸的生物力学和生理学后果。然而，关于阿仑膦酸钠对椎间盘细胞的影响仍有许多问题没有得到解答。本研究的目的是确定细胞外渗透压和氧张力在阿仑膦酸钠调节GAG产生中的作用及其对软骨和椎间盘基质周转的影响。从跖骨关节的软骨组织和牛尾椎间盘的髓核中分离细胞，包封在藻酸盐珠中，并在含有6%胎牛血清（FCS）的DMEM中以400 mOsmol以4百万细胞/ml的细胞密度培养。然后在21%氧气和10^<-1>-10 ^<-12>mol/l阿仑膦酸钠的条件下培养5天，以不含阿仑膦酸钠的细胞作为对照，比较渗透压和氧气浓度的影响。酶促测定乳酸盐产生，并使用DMB测定法检查糖胺聚糖（GAG）蓄积。硫酸盐GAG合成的速率使用标准的<35>2S-硫酸盐放射性方法测量。结果表明，10 <-10>- 10 μ <-8>mol/l的阿仑膦酸钠在培养5天后可增强软骨细胞和椎间盘细胞每百万细胞的GAG产量。在10 μ mol/l时增强效应最大<-8>。在<-8>病理条件下（270 mOsmol，&lt;1%氧气），阿仑膦酸钠（10 μ mol/l）诱导的每百万细胞GAG产量增加可通过抑制细胞代谢来阻止，如骨关节炎和椎间盘退变所见;但在健康条件下（400 mOsmol，5%氧气），阿仑膦酸钠可增加GAG产量、细胞代谢（乳酸盐产量）和GAG合成。总之，这些数据表明，阿仑膦酸钠可能对健康细胞有软骨保护作用。

Bisphosphonates have been widely used for treatment of osteoporosis. Recently, alendronate may have chondroprotective effects that could be of relevance in osteoarthritis. Aggrecan concentration falls markedly during cartilaginous and disc degeneration with unfortunate biomechanical and physiological consequences. However, many questions on the effect of alendronate to disc cells remain unanswered. The goals of this study were to determine the role of extracellular osmolality and oxygen tension in regulating production of GAG by alendronate and its effects on cartilahious and disc matrix turnover.Cells were isolated from the cartilaginous tissue of metatarsal joint and the nucleus pulposus of bovine caudal discs, encapsulated in alginate beads, and cultured in DMEM containing 6% foetal calf serum(FCS) at 400 mOsmol at cell densities of 4 million cells/ml. They were then cultured for 5 days under 21% oxygen with 10^<-1>-10^<-12> mol/l alendronate ; cell cultured without alendronate served as control and the effects of osmolarity and oxygen concentration were compared. Lactate production was measured enzymatically and glycosaminoglycan(GAG) accumulation was examined using a DMB assay. Rate of sulfate GAG synthesis was measured using a standard^<35> S-sulfate radioactive method. In the result, Alendronate at concentrations of 10^<-10>-10^<-8> mol/1 potentiated the GAG production per million cells by cartilaginous and disc cells in 5 days culture. The potentiated effect was maximal at 10^<-8> mol/l. Alendronate(10^<-8> mol/l)-induced increases in GAG production per million cells are prevented by inhibition of cell metabolism under pathologic conditions(270 mOsmol,<1% oxygen) as seen the osteoarthritis and degenerated disc ; but alendronate increased GAG production, cell metabolism(lactate production) and GAG synthesis in healthy conditions(400 mOsmol, 5% oxygen). In conclusion, this data suggest that alendronate may have chondroprotective effects on healthy cells.