Evaluation of osteoblast response to porous bioactive glass (45S5) substrates by RT-PCR analysis

Previous studies have shown that neonatal rat calvaria osteoblasts elaborat e substantial amounts of extracellular material with bone-like characterist ics when cultured on porous bioactive glass substrates in vitro. However, t he osteoblastic response to this material has not been fully characterized. The objective of this study was to characterize osteoblast response to por ous bioactive glass substrates following the expression of the classical ma rkers for osteoblast differentiation. In this study we synthesized porous b ioactive glass substrates, seeded them with osteoblast-like cells (ROS 17/2 .8) and followed the temporal expression of alkaline phosphatase (AP) activ ity, as well as the expression of mRNA for collagen type I (Coll-1), osteon ectin (OSN), osteopontin (OPN), osteocalcin (OCN), and bone sialoprotein (B SP). The data confirm that porous bioactive glass substrates are capable of supporting the in vitro growth and maturation of osteoblast-like cells. At a porosity of 42% and an average pore size of 80 mu m, the substrates prom ote the expression and maintenance of the osteoblastic phenotype. The resul ts additionally suggest that there is both a solution-mediated and a surfac e-controlled effect on cell activity.