Polyether ether ketone (PEEK) has been increasingly employed as biomaterials for trauma, orthopeadic, and spinal implants. However, concern has been raised about the inertness of PEEK which limits bone integration. In this study, we have coated PEEK with a functional material seeking to promote osteogenic differentiation of human mesenchymal stem cells (hMSC). We have used spray drying to coat poly(ethyl acrylate) (PEA) as a coating on PEEK. This technique is simple, allows a range of controlled coating thicknesses (from hundred nm to a few um), cost effective and easily translatable to scaffolds or implant surfaces for existing or new orthopaedic applications. PEA induces the organisation of fibronectin (FN) into nanonetworks upon simple adsorption from protein solutions. These FN nanonetworks on PEA represent a microenvironment for efficient growth factor binding and presentation in very low but effective doses. In this study we show cell adhesion and stem cell differentiation towards an osteogenic lineages when bone morphogenetic protein 2 (BMP2) was adsorbed on these engineered PEEK/PEA/FN microenvironments in very low doses. Overall, the developed functional coatings on PEEK has the potential to allow the translation of this material into orthopaedic applications.
Recent studies have shown that random disorder nanotopography increases osteoblast differentiation and bone formation. This has great potential merit in producing surfaces where osteointegration is required such as spinal fusion surgery and arthroplasty. However, the long-term failure of orthopaedic implants is often related to osteoclast mediated osteolysis and loosening. It is vitally important that we understand the effect of nanotopography on osteoclast formation and bone remodeling. We developed an unique osteoblast/osteoclast co-culture system derived from human mesenchymal and haematopoetic stem cells. This was co-cultured on both nanopatterned and unpatterned polycarbonate substrates. We assessed the co-culture using electron microscopy (SEM), protein expression using immunofluorescence and histochemical staining and gene expression using polymerase chain reaction (PCR). Co-culture of both osteoclasts and osteoblasts was confirmed with mature bone nodules and resorption pits identified on both surfaces. Significantly increased osteoblast differentiation and bone formation was noted on disordered nanotopography. Antagonistic genes controlling osteoclast activity were both upregulated with no significant difference in osteoclast marker gene expression. Our results confirm successful co-culture of osteoblasts and osteoclasts using an unique method closely resembling the
