Effect of transforming growth factor-beta on osteoblast cells cultured on 3 different hydroxyapatite surfaces

In this study, the specific objective was to investigate the combined effec t of different treatments of transforming growth factor-beta (TCF-beta) and hydroxyapatite (HA) on osteoblast response in vitro. Since the nature of b one cell responses in vitro is influenced by the properties of HA ceramics, this study was divided into 2 components: a chemical and crystallographic characterization of the HA ceramics, and an in vitro cell culture study. Si ntered HA samples were observed to have the highest crystallite size, compa red to as-received HA and calcined HA samples. No differences in surface ro ughness and chemical composition were observed between the sintered, calcin ed, and as-received HA surfaces. In concurrence with the x-ray diffraction, high-resolution x-ray photoelectron spectroscopy of Ca 2p also indicated a higher crystallinity on sintered HA samples compared to calcined and as-re ceived HA samples. Protein production by osteoblast cells was not statistic ally different on the 3 HA surfaces in the absence of TGF-beta. However, th ere was a dose-dependent increase in TGF-beta-stimulated protein produc tio n on the 3 different HA surfaces. As indicated by increased alkaline phosph atase-specific activity, as well as 1,25 (OH2) vitamin D-3-stimulated osteo calcin production, a more differentiated osteoblastlike phenotype was obser ved on the sintered HA surfaces compared to the as-received HA and calcined HA surfaces. An increased osteoblast-like cell activity on sintered HA sur faces in the presence of different TGF-beta dosage suggested that sintering of HA surfaces may play an important role in governing cellular response.