SUPPRESSION OF OSTEOBLAST FUNCTION BY TITANIUM PARTICLES

In order to understand the effect of particulate debris on osteoblast function, we studied the effect of different particles, including tita nium and polystyrene, on bone collagen mRNA (messenger RNA) with the u se of Northern blot hybridization analysis, and we studied the effect of the particles on the biosynthesis of bone collagen with analysis of H-3-proline incorporation and with the Western blot technique, The st eady-state levels of mRNA for procollagens alpha(1)(I) and alpha(1)(II I) were markedly suppressed in human MG-63 osteoblast-like cells expos ed to phagocytosable titanium particles that were smaller than three m icrometers. Both titanium and polystyrene particles smaller than three micrometers suppressed the expression of the gene that codes for coll agen, and the suppression of the expression of the gene was related to the size but not to the composition of the particles. The biosynthesi s of both type-I and type-III collagen also was decreased in cells tha t had been treated with titanium particles, Neither the viability nor the proliferation of cells was affected by particulate debris. These d ata indicate that phagocytosable titanium particles can significantly suppress the expression of the gene that codes for collagen in osteobl ast-like cells (p < 0.05).