Primary human osteoblast and mesenchymal stem cell responses to apatite/tricalcium phosphate bone cement modified with polyacrylic acid and bioactive glass.

In this work, three different modified cements, control apatite/beta-tricalcium phosphate cement (CPC), polymeric CPC (p-CPC), and bioactive glass added polymeric cement (p-CPC/BG) were evaluated regarding their physical properties and the responses of primary human osteoblast cells (HObs) and mesenchymal stem cells (MSCs). Although polyacrylic acid (PAA) increased compressive strength and Young's modulus of the cement, it could cause poor apatite phase formation, a prolonged setting time, and a lower degradation rate. Consequently, bioactive glass (BG) was added to PAA/cement to improve its physical properties, such as compressive strength, Young's modulus, setting time, and degradation. For in vitro testing, HObs viability was assessed under two culture systems with cement-preconditioned medium (indirect) and with cement (direct). HObs viability was examined in direct contact with cements treated by different prewashing conditions. HObs presented a more well spread morphology on cement soaked in medium overnight, as compared to other cements with no treatment and washing in PBS. In addition, the proliferation, differentiation, and total collagen production of both HObs and MSCs adhered to the cement were detected. Cells showed excellent proliferation on PAA/cement and PAA/BG/cement. Furthermore, the higher released Si ion and lower acidosis of PAA/BG/cement-conditioned medium resulted in an increase in osteogenic differentiation (HObs and MSCs) and enhanced collagen production (HObs in osteogenic medium and MSCs in control medium). Therefore, our findings suggest that BG incorporated PAA/apatite/ß-TCP cement could be a promising formula for bone repair applications.

Nodule formation and mineralisation of human primary osteoblasts cultured on a porous bioactive glass scaffold.

The aim of this study was to analyse human osteoblast responses to a porous bioactive glass scaffold. It was hypothesised that osteoblasts would attach, proliferate and form mineralised nodules in response to culture on the bioactive glass. As dissolution products are a key feature of bioactive glasses, this was measured by inductively coupled plasma optical emission spectroscopy to determine effects of both the glass surface and ion release. Osteoblasts attached and proliferated on the foams as demonstrated by scanning electron microscopy. Nodule formation was also observed in the pores of the glass and also in conditioned medium containing dissolution products at certain concentrations and these nodules were shown to be mineralised by alizarin red staining. Undiluted dissolution products from the foams however caused significant apoptosis suggesting an ion concentration dependent response.