Osteoblast Behaviour on Injectable Biomaterials Intended for Augmentation of Vertebral Compression Fractures

Abstract: Biomaterials used for stabilization of compressed vertebraes due to osteoporosis, have mainly been based on resin materials, like PMMA (polymethyl methacrylate), but have recently expanded to consist of injectable ceramics, such as calcium-aluminate. In this in vitro study human osteoblast-like cells, MG-63, were cultured on three different injectable biomaterials based on: Ca-aluminate, Bis-GMA (bisphenol A-glycidylmethacrylate) and PMMA, to investigate the cellular response elicited by these materials. Cell proliferation was measured by the NucleoCounter® system, cell viability was investigated by LDH (lactate dehydrogenase) analysis, cell differentiation and mineralization was evaluated by mRNA gene expression of the osteoblastic markers: ALP (alkaline phosphatase), OC (osteocalcin) and COLL-I (collagen type I) by qPCR (quantitative polymerase chain reaction) analysis. Two control materials were used: TCP (tissue culture polystyrene, negative control) and PVC (polyvinyl chloride, positive control). The results showed that all the bone cement materials were non-toxic and biocompatible, i.e. they provided good cell viability and proliferation of the MG-63 cells. They are specific for bone cells, since they expressed high values of the osteoblast-specific differentiation markers, and are thus promising as injectable bone cement materials. Among the bone cements, Xeraspine appears to be the most biocompatible material for bone cells. It is followed by Cortoss and then Vertebroplastic.