Attachment and proliferation of osteoblasts and fibroblasts on biomaterials for orthopaedic use

Using a variety of cell types, cell attachment and growth was studied on prospective (polyethersulphone (PES) and polyetheretherketone) and currently used (titanium 318 alloy, cobalt chrome molybdenum alloy and ultra-high molecular weight polyethylene (UHMWPE)) orthopaedic biomaterials. Proliferation of fibroblasts and osteoblasts was measured using incorporation of tritiated thymidine into total DNA. Attachment of cells was assessed by indirect immunofluorescent labelling of vinculin, a component of the cell's focal adhesion plaque. The degree of cell attachment was quantified on the materials by determining the mean number of adhesion plaques and using an image analysis system to determine the mean total area of plaques per cell. Fibroblasts and osteoblasts responded differently to the materials tested. When grown on PES surfaces, rat tail fibroblasts synthesized significantly greater amounts of DNA than cells on all other surfaces, whilst fibroblasts on UHMWPE synthesized significantly less DNA than cells on all other materials. Interestingly, there was no significant difference between the amounts of DNA synthesized by osteoblasts grown on the various materials. Determination of the number of vinculin adhesion plaques per cell and the mean total area of the plaques per cell showed that the attachment of fibroblasts to UHMWPE was significantly reduced compared with other materials. In contrast there was no significant difference in the adhesion of osteoblasts to different materials. Scanning electron microscope (SEM) observations of cells on the materials correlated with the morphometric data. Cells with the greatest number and area of adhesion plaques were well spread and flattened whilst those with the least number of adhesion plaques were more rounded and less spread.