Abstract:

Background: This study tested the hypothesis that various silicon ions concentrations have effects on osteoblast proliferation, gene and extracellular matrix expression. It also explored possible pathway of how silicon is effecting osteoblast differentiation.

Methods: MC3T3 cells were grow in vitro with alpha-mem solution and were treated with 10, 100, 1000uM silicon solution, and combination of Sp7/Osterix SiRNA and silicon solution. Cells were treated with cell proliferation assay, stained with Picosirius staining, and gene expressions were measured with reverse transcriptase polymerase chain reaction.

Results: Silicon treatment alone did not have an effect on cell proliferation compared to control during a 6-day period. Histology slides showed 100uM silicon has the most collagen fibrils compared to 10uM, 1000uM, and control on day 1. By day 7 the control and 100uM showed comparable amount of collagen fibrils where 10uM and 1000uM treatments had much fewer visible fibrils. Gene expression results agreed with histology slides. On day 1, cells with 100uM silicon treatment had a significant increase (p<0.05) in Col1α1 expression, and cells with 1000uM silicon had an increase (p<0.05) in Col1α2 expression. There were no significant differences in gene expression with various treatments by day 7. 100uM silicon caused significant increase (p<0.05) gene expressions for Sp7, Col5α3, BMP1, and Smad 5. Cells treated Sp7/Osterix SiRNA showed a significant decrease gene expression in Sp7, BMP1, Smad4, Smad5, and AKP2.

Conclusion: Silicon treatment did not effect cell proliferation, but did increase collagen expression in osteoblast cells. 100uM was the most optimum concentration for collagen expression compared to 10uM and 1000uM. One possible mechanism of how silicon effects osteoblast cells is through BMP1, that increase Smad5 production, and leads to cells signaling for more collagen production. More work is needed to confirm the mechanistic effect of silicon.