55S bioglass promoted differentiation of cultured rat osteoblasts and created a template for bone formation

摘要

We investigated the behavior of fetal rat osteoblasts cultured on bioactive glass with 55wtpercent silica content (55S) and on bioinert glass (60S). Morphological observations revealed that cells attached and spread to all substrata and formed multi-layered nodular structures by day 10 of culture. Cytoenzymatic localization of alkaline phosphatase (AP) and immunolabeling with bone sialoprotein antibody revealed a specific staining for the bone nodules formed in the 55S cultures. Furthermore, biochemical determination of AP activity after 12 days in culture revealed a significantly higher content of the isoenzyme for the 55S cultures than for the controls. Ultrastructural observations of undecalcified sections revealed the presence of an electron-dense layer, composed of needle-shaped crystals at the periphery of the material, that seemed to act as a nucleating surface for biological crystals. This data indicate better osteoblast expression on 55S bioactive glass compared to non-bioactive glass and revealed that mineralization can be initiated in vitro with 55S bioactive glass serving as a template for bone formation and controlling nucleation of biological crystals.