Fluoride incorporation in high phosphate containing bioactive glasses and in vitro osteogenic, angiogenic and antibacterial effects

ObjectivesTo manufacture and assess bioactivity of low fluoride/high phosphate (low F−/high P2O5) bioglasses (BGs). Then the effects of BG-conditioned medium on osteoblast-like cell behavior and BG particles on bactericidal activity were investigated.MethodsBGs (0-7% F− content, constant 6.33% P2O5 in mol%) were designed and produced. BG particles was immersed in Tris Buffer solution or α-MEM to determine apatite formation and ion (Ca, P, Si and F) release. Osteoblast-like cells MC3T3-E1 were treated with BG-conditioned medium and assessed for cytotoxicity, pre-osteogenic and pro-angiogenic responses. Antibacterial ability was explored by incubating sub-gingival bacteria with BG particulates.ResultsRapid apatite formation was observed in F− containing BGs after only 2-8 h immersion in Tris buffer solution. In the F− free group, apatite was not detectable until 72 h. Peak Ca, P and F release into Tris buffer was at 2 h immersion, and then the levels decreased. In α-MEM, apatite formation in all the BGs was undetectable until 72 h immersion. Alkaline phosphatase activity, cell number, collagen formation, bone-like mineral nodules and osteogenic gene expression of MC3T3-E1 cells were significantly promoted in low F− BG (P6.33F1) conditioned medium. MC3T3-E1 VEGF gene expression was increased, and protein production was dose-dependently promoted with F− BG-conditioned medium. After incubation with BG particulates, the growth of sub-gingival bacteria, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis, was significantly inhibited; the antibacterial activity being dependent on the F− content of the BGs.SignificanceThese results show that low F−/high P2O5 BGs significantly accelerated apatite formation and promoted both pre-osteogenic and pro-angiogenic responses of MC3T3-E1 osteoblast-like cells and inhibited the growth of periodontal pathogens in vitro. These BGs may prove useful as bone graft substitutes.