UHMWPE oxidation increases matrix metalloproteinase-2 (MMP-2) release in human fibroblast

MRC-5 human fibroblast were grown polystyrene plates, UHMWPE slices and UHMWPE slices oxidized in air in oven at 120degreesC for 80 h. Cell proliferation and cytotoxicity were assessed after 24, 48, and 72 h. Control cells grown on polystyrene doubled their number after 72 h while both cell population grown on UHMWPE and oxidized UHMWPE showed a reduced proliferation rate. Both UHMWPE types seem to induce a cytostatic rather than a cytotoxic effect, in fact, no difference in the LDH release were observed between the three cell populations at 24, 48, and 72 h. Gelatinase activity was assessed in cell medium at every time point using gelatin zymography. Only gelatinase B (MMP-2) activity was present in MRC-5 conditioned medium. Oxidized UHMWPE induced a strong release of MMP-2 after 72 h compared to control and UHMWPE samples. The augmented MMP-2 release in the absence of a cytotoxic phenomenon suggests a possible role for UHMWPE oxidation in the MMPs stimulation observed in the periprosthetic tissues.