Novel engineered human fluorescent osteoblasts for scaffolds bioassays

Many cellular models have been used to investigate bone substitutes including coral-derived hydroxylapatite (HA). The aim of this study was to verify whether a new cellular model represented by Saos-eGFP cells can be used to test biomaterials by in vitro assays. Saos-eGFP cells which express the enhanced Green Fluorescent Protein (eGFP), were derived from the osteoblast-like cell line Saos-2. To this purpose Saos-eGFP cells were employed to investigate the in-vitro bioactivity of a well characterized coral-derived HA biomaterial, in block and granule forms. This engineered cell line, by evaluating the emitted fluorescence, allowed us to assay (i) cell adhesion, (ii) cell proliferation and (iii) colony capability. Electron microscopy analysis was employed to evaluate the (iv) morphology of cells seeded on the biomaterial surface. (v) Histological analysis of the bone grown after scaffold implantation was carried out in specimens from two clinical cases. Saos-eGFP cells indicate, as established before, that the coralline-HA biomaterials has a good in vitro cytocompatibility when tested with human osteoblast-like cells. Some differences in proliferation activity was detected for the two different forms assayed. Cytocompatibility data from in vitro analyses were confirmed by in vivo behaviour of biomaterials. Our tests suggest that the engineered cell line Saos-eGFP represents a suitable in vitro mode for studying the biocompatibility, the cell adhesion, spreading and proliferation on biomaterials developed for clinical applications. The main advantages of this cellular model are (i) less time consuming and (ii) a reduced cost of the experiments.