title: [Biological mechanism of macrophage activation by wear particles at the bone-implant interface].
abstract: OBJECTIVE
  To observe the response of membrane Ca(2+) channel of macrophage-like cells (MCs) to wear particles and analyze the cytoplasmic [Ca(2+)]i change in macrophage activation at the bone-implant interface.
  
  
  METHODS
  The synoviocyte system of normal hip joint was established in vitro. Immunohistochemical technique (SABC) with CD68 Mab was used to differentiate MCs and fibroblast-like cells (FCs) in the system, and the time when MCs begin to perform phagocytosis was determined by SEM. 1.5 mg/ml (W/V) Ti alloy, Co-Cr alloy or UHMWPE particles suspension was added into the system to monitor the [Ca(2+)]i change in the MCs by confocal laser scanning microscope (CLSM).
  
  
  RESULTS
  Phagocytosis of MCs happened after 6 hours, but within 1 hour the Ca(2+) channel of their cell membrane opened for 1 - 6 times and caused rapid and transient pulses of [Ca(2+)]i in cytoplasm after different period of incubation. There was no significant difference between times or range of the [Ca(2+)]i pulse (P > 0.05). The group of UHMWPE particles had the longest incubation period (P < 0.05), but the interval of pulses was shorter than that in the group of Co-Cr alloy particles (P < 0.05). [Ca(2+)]i pulses still appeared when MCs were incubated by indomethecin (P > 0.05), but the phenomenon could be blocked by nimodipin.
  
  
  CONCLUSIONS
  Activation of macrophages at the bone-implant-interface could happen before they phagocytose wear particles. The primary switch-on mechanism of osteolysis mediated by cytokines at the bone-implant interface may be the opening of membrane Ca(2+) channel and pulse-like Ca(2+) influx of macrophages when stimulated by wear particles.
authors.affiliation: General Hospital, Chinese People's Liberation Army, Beijing 100853.
authors.forename: X
authors.initials: X
authors.lastname: Cai
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: Y
authors.initials: Y
authors.lastname: Hu
authors.forename: S
authors.initials: S
authors.lastname: Lu
authors.forename: W
authors.initials: W
authors.lastname: Bi
authors.forename: N
authors.initials: N
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Chuang
mesh_terms: D001672:Biocompatible Materials / Q000009:adverse effects*; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D007595:Joint Prosthesis; D008262:Macrophage Activation / Q000187:drug effects* / Q000502:physiology; D018613:Microscopy, Confocal; D010014:Osteolysis / Q000139:chemically induced; D011475:Prosthesis Failure; D013583:Synovial Membrane / Q000166:cytology
chemical_list: D001672:Biocompatible Materials; D015220:Calcium Channels; D002118:Calcium