Characterization of a mineralizing bone-like culture system for evaluation of biological interactions with medical devices. This project was designed to (a) explore the parameters of cell proliferation and cellular expression of a bone derived cell type by using primary rat calvarial derived osteoblast-like cells. Conditions that effect cell responses were explored. This included the determination that cell density at 5 X 104 cells/mm2 will provide a culture system capable of developing mineralizing nodules in the presence or not of exogenous phosphate sources. This system was not found to proliferate but instead allow for the acceleration of the developmental plan in which bone specific markers were used to characterize the formation of the mineralizing matrix. These markers involved the developmental osteonectin, BAG-75 and other noncollagenous proteins. These assorted assay were then used to evaluate the formation of bone matrix as a function of different titanium oxide surfaces that were altered through different sterilizing treatments. A second component of this project involved the exploration of the cell kinetics and equilibrium condition of cell adhesion using osteoblast-like cells derived in the same way as described above. The results on this series of studies suggests that in contrast to the current paradigm concerning the relative importance of cell surface integrin family members (in mediating cell adhesion) that cell surface glycosaminoglycans (especially cell surface Chondroitin Sulfate/Dermatan Sulfate as well as Heparan Sulfate) are of critical importance in mediating osteoblast cell adhesion to biomaterial surfaces when assayed in this cell adhesion system. The use of these two approaches, evaluation of a mineralizing bone culture system and the formation of a cell adhesion system in which the cell surface GAG's critical in mediating cell adhesion allows the formation and exploration of mechanistic models for the improved design of artificial materials used in orthopaedics and dentistry.
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