title: Effect of size and dose on bone resorption activity of macrophages by in vitro clinically relevant ultra high molecular weight polyethylene particles.
abstract: Polyethylene wear debris generated at the bearing surfaces of total artificial hip joints is thought to play an important role in the periprosthetic osteolysis and ultimately the aseptic loosening of these prostheses. The macrophage is believed to be central to this process by releasing various cytokines and other mediators of osteolysis upon phagocytosis of the polyethylene wear debris. This study evaluated the in vitro bone resorption response of C3H murine peritoneal macrophages to clinically relevant GUR 1120 polyethylene particles. Macrophages were co-cultured in vitro with GUR 1120 particles with a mean size of 0.24, 0.45, 1.71, and 7.62, and GUR 1120 polyethylene resin with a mean size of 88 microm at various particle volume (microm)(3): macrophage ratios (0.1:1; 1:1; 10:1; and 100:1). The conditioned supernatants were incubated with (45)calcium radio-labeled mouse calvariae, and bone resorption was measured as (45)calcium release. The results showed that the 0.24 microm particles stimulated the macrophages to generate bone resorbing activity at a ratio of 10(microm)(3) per macrophage. The 0.45 and 1.71 microm particles were active at a ratio of 100( microm)(3) per macrophage, and the 7.62 and 88 microm particles were inactive at all the doses tested. The co-culture supernatants were also assayed for TNF-alpha, IL-1beta, IL-6, and PGE(2). The results followed the same trend for particle size and volume dose to that observed for the bone resorbing activity. This study has demonstrated, for the first time, the importance of size and dose of clinically relevant polyethylene particles on the osteolytic response of macrophages in vitro.
authors.affiliation: Departments of Biochemistry & Molecular Biology (Division of Microbiology), University of Leeds, Leeds LS2 9JT, UK.
authors.forename: T R
authors.initials: TR
authors.lastname: Green
authors.forename: J
authors.initials: J
authors.lastname: Fisher
authors.forename: J B
authors.initials: JB
authors.lastname: Matthews
authors.forename: M H
authors.initials: MH
authors.lastname: Stone
authors.forename: E
authors.initials: E
authors.lastname: Ingham
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology*; D001862:Bone Resorption / Q000503:physiopathology*; D002132:Calcium Radioisotopes / Q000493:pharmacokinetics; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D006622:Hip Prosthesis; D017737:Macrophages, Peritoneal / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008809:Mice, Inbred C3H; D008970:Molecular Weight; D011095:Polyethylenes / Q000494:pharmacology*; D011475:Prosthesis Failure; D012886:Skull / Q000502:physiology
chemical_list: D001672:Biocompatible Materials; D002132:Calcium Radioisotopes; C118164:GUR 1120; D011095:Polyethylenes