Effects Of Aluminum Trichloride On Mineralization Process In Cultured Rat Osteoblasts

This experiment investigated the effect of Aluminum Trichloride (AICl3) on mineralization process in cultured rat osteoblasts (OB). OB was cultured to4th generation with mineralization medium (containing10mmol·L-1β-glycerophosphate,50μg·mL-1ascorbic acid and0.1μmol·L-1dexamethasone) and exposed to0(control group, CG),0.52mmol·L-1AICl3(test group, TG) for7,14and21d, respectively. The mineralized matrix nodules, the activity of bone alkaline phosphatase (B-ALP) in supernatant, the concentrations of extracellular calcium (Ca) and inorganic phosphate (Pi), the mRNA and protein expressions of osteopontin (OPN), and the mRNA expressions of type-Icollagen (CoL I), bone sialoprotein (BSP), transforming growth factor-β1(TGF-β1) and osteocalcin (OCN) were measured at the7,14and21d, respectively. The results showed as follows:1. The mineralized nodules in TG were less than in CG at the7,14and21d. And with the extension of experiment time, mineralized nodules increased in CG and decreased in TG increasingly, AlCl3decreased nodule formation.2. The concentration of extracellular Ca was lower and Pi was higher in TG than those in CG at the7,14and21d (P<0.01). The concentration of extracellular Ca was uptrend and Pi was downtrend with the extension of time in CG and TG. And there was a time-dependent effect. Thus, in our study, AlCl3inhibited the generation of mineral salts.3. The mRNA expression of CoL I (P<0.05; P<0.01) in TG were lower than those in CG at the7,14and21d. AlCl3inhibited stent of bone mineralization production.4. The mRNA expression of OCN in TG was lower than that in CG at the7and14d (P<0.01), AICl3suppressed the mineralization at the early and interim; the mRNA expression of BSP (P<0.01) in TG were lower than those in CG at the7,14and21d, AlCl3suppressed the startup of mineralization; the mRNA and the protein expressions of OPN in TG were lower than that in CG at the7,14and21d (P<0.01). AlCl3suppressed the regulation of mineralized crystal size and shape in the mineralization process.5. The B-ALP activity in supernatant in TG was lower than that in CG at the7,14and21d (P <0.01). And with the extension of experiment time, the B-ALP activity decreased in CG and TG increasingly, AlCl3decreased the generation of Pi.6. The mRNA expression of TGF-β1(P<0.01) in TG were lower than those in CG at the7,14and21d, AlCl3decreased OB mineralization.The above results showed that AlCl3suppressed mineralization process and formation of mineralized nodules by the inhibited the generation of mineral salts, reduced production of mineralization stent, reduced the non-collagen proteins, the activity of B-ALP and regulatory factors on mineralization in rat OB. And, the results may provide a theoretical foundation for revealing the pathogenesis of aluminum-related bone disease.