The role of orthosilicic acid-induced autophagy on promoting differentiation and mineralization of osteoblastic cells:

Silicon, an element, has been reported to possess various osteogenic biological functions. However, the precise cellular action mechanism of silicon in osteogenesis is elusive. Here, we examine whether autophagy is associated with the osteogenic differentiation and mineralization of preosteoblasts stimulated by orthosilicic acid (unique soluble form of silicon). The autophagy induced by silicon was detected via autophagy-related protein expression. The correlation between orthosilicic acid-induced autophagy and the osteogenic process was verified by the autophagy inhibitor 3-methyladenine. We also investigated its applicability in vivo through bone mineral density, collagen staining, hydroxyproline, and immunohistochemistry on osteoporosis rats. Concentrations above 10 µM increased alkaline phosphatase activity, whereas those up to 50 µM decreased alkaline phosphatase activity. Orthosilicic acid at concentrations up to 20 µM increased the osteogenetic indicators, the expression of the autophagy-related fa...