COMPARISON OF THE EARLY PRODUCTION OF EXTRACELLULAR-MATRIX ON DENSE HYDROXYAPATITE AND HYDROXYAPATITE-COATED TITANIUM IN CELL AND ORGAN-CULTURE

In order to investigate the earliest changes at the bone-hydroxyapatit e (HA) interface, two materials, dense HA and HA-coated titanium alloy , were investigated for their ability to stimulate production of extra cellular matrix both in cell and organ culture. Osteoblast-like cells were obtained from rabbit calvariae after preliminary culture for 3 d and seeded out onto the two materials. When these cells were grown in culture on the dense HA no matrix production was seen with the scannin g electron microscope after 4 d, but there did appear to be matrix pro duced on the rougher surface of the HA coating. In contrast, extracell ular matrix production was greatly increased in organ culture where th e material was placed on a section of bone, particularly on the HA coa ting, where it formed an organized layer of collagen within 4 d. These results showed that extracellular matrix production by both osteoblas tic cells and in calvarial culture was greater on the HA coatings than dense HA. In addition, organ culture allows the investigation of the earliest changes in the bone-HA interface without having to undertake in vivo implantation studies of such short duration.