Specific response of osteoblast-like cells on hydroxyapatite layer containing serum protein

AP40 Bioactive Glass Ceramic by Sol-Gel Synthesis: In Vitro Dissolution and Cell-Mediated Bioresorption

In this work, the sol-gel synthesis of AP40 bioactive glass system was reported. The obtained powder was fully characterised in terms of microstructure, composition and thermal behaviour by X-ray diffraction (XRD) measurements, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry and differential thermal analysis (TG-DTA).In vitrodissolution tests were performed in order to assess the degradation behaviour of sol-gel derived AP40 samples thermally treated at different temperatures. Finally, preliminary results on cytocompatibility are reported, based on bioresorption activity of human peripheral blood monocytes differentiated into osteoclasts on sintered disks.

Apatite content of collagen materials dose-dependently increases pre-osteoblastic cell deposition of a cement line-like matrix

Bone matrix, mainly composed of type I collagen and apatite, is constantly modified during the bone remodeling process, which exposes bone cells to various proportions of mineralized collagen within bone structural units. Collagen-mineralized substrates have been shown to increase osteoblast activities. We hypothesized that such effects may be explained by a rapid secretion of specific growth factors and/or deposition of specific matrix proteins. Using MC3T3-E1 seeded for 32h on collagen substrates complexed with various apatite contents, we found that pre-osteoblasts in contact with mineralized collagen gave rise to a dose-dependent deposit of Vascular Endothelial Growth Factor-A (VEGF-A) and RGD-containing proteins such as osteopontin (OPN) and fibronectin (FN). This RGD-matrix deposition reinforced the cell adhesion to collagen-mineralized substrates. It was also observed that, on these substrates, this matrix was elaborated concomitantly to an increased cell migration, allowing a homogeneous coverage of the sample. This particular surface activation was probably done firstly to reinforce cell survival (VEGF-A) and adhesion (OPN, FN) and secondly to recruit and prepare surfaces for subsequent bone cell activity.