title: The effect of ultra-high molecular weight polyethylene wear debris on MG63 osteosarcoma cells in vitro.
abstract: BACKGROUND
  Focal osteolysis due to ultra-high molecular weight polyethylene wear debris involves effects on both bone resorption and bone formation.
  
  
  METHODS
  The response of MG63 osteoblast-like osteosarcoma cells to ultra-high molecular weight polyethylene wear debris isolated by enzymatic digestion of granulomatous tissue obtained from the sites of failed total hip arthroplasties was examined. Scanning electron microscopy, particle-size analysis, and Fourier transform infrared spectroscopy were used to characterize the number, morphology, size distribution, and chemical composition of the particles. Cell response was assessed by adding particles at varying dilutions to confluent cultures and measuring changes in cell proliferation (number of cells and [3H]-thymidine incorporation), osteoblast function (alkaline-phosphatase-specific activity and osteocalcin production), matrix production (collagen production and proteoglycan sulfation), and local cytokine production (prostaglandin-E2 production).
  
  
  RESULTS
  The mean size of the particles was 0.60 micrometer, and 95 percent of the particles had a size of less than 1.5 micrometers. The number of particles per gram of tissue ranged from 1.39 to 3.38x10(9). Three of the four batches of particles were endotoxin-free. Exposure of the cells to particles of wear debris significantly increased the number of cells (p<0.05) and the [3H]-thymidine incorporation (p<0.05) in a dose-dependent manner. In contrast, the addition of particles decreased alkaline-phosphatase-specific activity and osteocalcin production. Collagen production and proteoglycan sulfation were also decreased, while prostaglandin-E2 synthesis was increased by the addition of particles.
  
  
  CONCLUSIONS
  Ultra-high molecular weight polyethylene particles isolated from human tissue stimulated osteoblast proliferation and prostaglandin-E2 production and inhibited cell differentiation and matrix production. These results indicate that particles of wear debris inhibit cell functions associated with bone formation and that osteoblasts may produce factors in response to wear debris that influence neighboring cells, such as osteoclasts and macrophages.
  
  
  CONCLUSIONS
  Particles of wear debris, especially ultra-high molecular weight polyethylene, have been implicated in the loosening of implants and the development of osteolysis. The present study shows that particles of ultra-high molecular weight polyethylene isolated from human tissue inhibit osteoblast functions associated with bone formation. In addition, particles of wear debris induced osteoblasts to secrete factors capable of influencing neighboring cells, such as osteoclasts and macrophages. These results suggest that osteoblasts may play a role in the cascade of events leading to granuloma formation, osteolysis, and failure of orthopaedic implants.
authors.affiliation: Department of Orthopaedics, University of Texas Health Science Center at San Antonio, Texas 78284-7774, USA. deand@uthscsa.edu
authors.forename: D D
authors.initials: DD
authors.lastname: Dean
authors.forename: Z
authors.initials: Z
authors.lastname: Schwartz
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: C R
authors.initials: CR
authors.lastname: Blanchard
authors.forename: C M
authors.initials: CM
authors.lastname: Agrawal
authors.forename: J D
authors.initials: JD
authors.lastname: Mabrey
authors.forename: V L
authors.initials: VL
authors.lastname: Sylvia
authors.forename: C H
authors.initials: CH
authors.lastname: Lohmann
authors.forename: B D
authors.initials: BD
authors.lastname: Boyan
mesh_terms: D000328:Adult; D000469:Alkaline Phosphatase / Q000378:metabolism; D002455:Cell Division; D003094:Collagen / Q000096:biosynthesis; D017077:Culture Media, Conditioned; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D008970:Molecular Weight; D010006:Osteoblasts / Q000473:pathology* / Q000502:physiology; D010014:Osteolysis / Q000378:metabolism*; D012516:Osteosarcoma / Q000473:pathology*; D010316:Particle Size; D011095:Polyethylenes; D011475:Prosthesis Failure; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D017077:Culture Media, Conditioned; D011095:Polyethylenes; D003094:Collagen; D000469:Alkaline Phosphatase; D013936:Thymidine