title: Systemic trafficking of macrophages induced by bone cement particles in nude mice.
abstract: Macrophages play an important role in the biological response to wear particles, which can result in periprosthetic osteolysis and implant loosening. In this study, we demonstrate that polymer particles induce systemic trafficking of macrophages by non-invasive in vivo imaging and immunohistochemistry. The distal femora of nude mice were injected with 10% (w/v) Simplex bone cement (BC) suspensions or saline (PBS). Reporter RAW264.7 macrophages which stably expressed the bioluminescent reporter gene fluc, and the fluorescence reporter gene gfp, were injected intravenously. Bioluminescence imaging was performed immediately and periodically at 2-day intervals until day 14. Compared to the non-operated contralateral femora, the bioluminescent signal of femora injected with BC suspension increased 4.7+/-1.6 and 7.8+/-2.9-fold at day 6 and 8, respectively. The same values for PBS group were 1.2+/-0.2 and 1.4+/-0.5, respectively. The increase of bioluminescence of the BC group was significantly greater than the PBS group at day 8 (p<0.05) and day 6 (p<0.1). Histological study confirmed the presence of reporter macrophages within the medullary canal of mice that received cement particles. Modulation of the signaling mechanisms that regulate systemic macrophage trafficking may provide a new strategy for mitigating the chronic inflammatory response and osteolysis associated with wear debris.
authors.affiliation: Department of Orthopaedic Surgery, Stanford University School of Medicine, R116, Edwards Building, 300 Pasteur Drive, Stanford, CA 94305-5326, USA.
authors.forename: Pei-Gen
authors.initials: PG
authors.lastname: Ren
authors.forename: Sheen-Woo
authors.initials: SW
authors.lastname: Lee
authors.forename: Sandip
authors.initials: S
authors.lastname: Biswal
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Goodman
mesh_terms: D000818:Animals; D001843:Bone Cements / Q000494:pharmacology*; D002465:Cell Movement / Q000187:drug effects*; D005269:Femur / Q000166:cytology; D005455:Fluorescent Antibody Technique; D005629:Frozen Sections; D008164:Luminescent Proteins / Q000378:metabolism; D008264:Macrophages / Q000166:cytology* / Q000187:drug effects*; D008297:Male; D051379:Mice; D008819:Mice, Nude; D008859:Microscopy, Polarization; D051598:Whole Body Imaging
chemical_list: D001843:Bone Cements; D008164:Luminescent Proteins