EFFECT OF POLYETHYLENE ON OSTEOCALCIN, ALKALINE-PHOSPHATASE AND PROCOLLAGEN SECRETION BY HUMAN OSTEOBLASTIC CELLS

We have studied the direct effects of polyethylene particles on osteob lastic function in primary human bone cell cultures. The cells were ob tained from trabecular bone fragments of patients undergoing knee reco nstructive surgery. When the cells reached confluency, they were subcu ltured into two flasks, one untreated (control culture) and the other treated with polyethylene particles, and incubated until confluency. O steoblastic function was evaluated by assaying osteocalcin, alkaline p hosphatase, and C-terminal procollagen type I, with and without 1,25(O H)(2)D stimulation, in the cell-conditioned medium. We found that addi tion of polyethylene to these osteoblastic cell cultures induced highe r levels of secreted osteocalcin after 1,25(OH)(2)D stimulation. Alkal ine phosphatase levels increased whereas C-terminal procollagen type I levels decreased in the cell conditioned medium after polyethylene wa s added to the cultures. Treatment of the control cultures with 1,25(O H)(2)D stimulated alkaline phosphatase levels and decreased C-terminal procollagen type I. However, these osteoblastic markers in 1,25(OH)(2 )D-treated cells did not change in cultures with polyethylene. This st udy demonstrates that polyethylene particles have a direct effect on o steoblastic markers in human bone cells in culture.