RESPONSE OF HUMAN OSTEOBLASTS TO POLYMETHYLMETACRYLATE IN-VITRO

The effects of a polymethylmetacrylate (PMMA) powder with a diameter b etween 0.5 and 25 mu m have been studied in vitro on several human ost eoblast populations obtained from different sources. Parameters of cel l activity such as cell growth, collagen synthesis, osteocalcin, and i nterleukin-6 (IL-6) production have been evaluated. Cell proliferation and collagen synthesis were inhibited after exposure to bone cement, whereas osteocalcin and IL-6 production were stimulated. These results suggest that PMMA particles could affect osteoblast activity in a way that could contribute, together with other factors, to periprosthetic osteolysis through two different pathways: a reduced periprosthetic b one formation due to the reduced osteoblast proliferation and collagen synthesis, and an osteoblast-mediated activation of osteoclastic bone resorption as suggested by the increased osteocalcin and IL-6 synthes is. In fact, osteocalcin has been demonstrated to have a role in osteo clast recruitment to bone surfaces, and IL-6 is known to induce osteoc lastogenesis and to directly stimulate bone resorption.