Comparison of the Influence of Phospholipid-Coated Porous Ti-6Al-4V Material on the Osteosarcoma Cell Line Saos-2 and Primary Human Bone Derived Cells

Biomaterial surface functionalization remains of great interest in the promotion of cell osteogenic induction. Previous studies highlighted the positive effects of porous Ti-6Al-4V and phospholipid coating on osteoblast differentiation and bone remodeling. Therefore, the first objective of this study was to evaluate the potential synergistic effects of material porosity and phospholipid coating. Primary human osteoblasts and Saos-2 cells were cultured on different Ti-6Al-4V specimens (mirror-like polished or porous specimens) and were coated or not with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) for three weeks or five weeks. Selected gene expressions (e.g., classical bone markers: alkaline phosphatase, osteocalcin, osteoprotegerin (OPG), receptor activator of nuclear factor kappa-β ligand (RANKL) and runt-related transcription factor 2) were estimated in vitro. Furthermore, the expressions of osteocalcin and osteopontin were examined via fluorescent microscopy at five weeks (immunocytochemistry). Consequently, it was observed that phospholipid coating potentiates preferences for low and high porosities in Saos-2 and primary cells, respectively, at the gene and protein levels. Additionally, RANKL and OPG exhibited different gene expression patterns; primary cells showed dramatically increased RANKL expression, whereas OPG expression was decreased in the presence of POPE. A synergistic effect of increased porosity and phospholipid coating was observed in primary osteoblasts in bone remodeling. This study showed the advantage of primary cells over the standard bone cell model.