Cells and Materials


Previous implantation experiments have investigated the interaction between a series of PEO/PBT copolymers (Polyactive®) and bone tissue, and shown the morphology of bone-bonding with several PEO/PBT ratios. However, the underlying mechanism of bone-bonding remains largely unknown. Therefore, an in-vitro approach was chosen to obtain more information on the events occurring at the PEO/PBT copolymer-bone interface. Rat marrow cells were cultured on two PEO/PBT copolymer proportions: a 60/40 ratio which is known to bond with bone tissue in-vivo and a 30170 ratio which, within one year of implantation, does not bond with bone. Evaluation was performed with light microscopy, scanning, backscatter and transmission electron microscopy and X-ray microanalysis.

Surface calcification of the 60/40 material was observed. Undecalcified specimens revealed a continuum between material calcification and biologically elaborated mineralized matrix. An electron-dense region was frequently observed at the interface of this material. No signs of calcification were seen within the surface of the stiffer 30/70 polymer. Mineralized matrix was found in contact with the surface of the 30/70 but the absence of a continuity was evident at all resolutions. These results indicate that reproduction of the in-vivo findings and a rapid differentiation between different PEO/PBT ratios can be accomplished in-vitro. The rat marrow system may therefore represent a controlled tool to achieve a better understanding of the events occurring at the bone PEO/ PBT copolymer interface.