Voronov, I 1, J. P. Santerre 1, A. Hinek 2, J. W. Callahan 2, J. Sandhu 4, E. L. Boynton 1, 4, 5 *
1Centre for Biomaterials, Department of Chemical Engineering, University of Toronto, Toronto, Canada 2Division of Cardiovascular Research, Research Institute, Hospital for Sick Children, Department of Pathology, University of Toronto, Toronto, Canada 3Division of Neurosciences, Research Institute, Hospital for Sick Children, Department of Biochemistry, University of Toronto, Toronto, Canada 4Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Department of Immunology, University of Toronto, Toronto, Canada 5Department of Surgery, University of Toronto, Women's College Hospital, 76 Grenville Street, Suite 244, Toronto, Ontario M55 182, Canada
Keywords: polyethylene particles; macrophages; phagocytosis; cytokines; histology
Abstract
In this study, an in vitro model has been developed to examine the interactions of macrophages with ultrahigh molecular-weight polyethylene (UHMWPE) and high-density polyethylene (HDPE) particles. Polyethylene particles are the major constituent of the material debris formed as a result of orthopedic implant wear. However, the study of polyethylene particle interactions with cells has been limited. UHMWPE (18-20 m) and HDPE (4-10 m) were suspended in soluble collagen type I and subsequently solidified on glass coverslips. The particle chemistry was characterized by Fourier transform infra-red spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Mouse cell line macrophages (IC-21) were established on the collagen-particle substrata and maintained for up to 24 h. The response of the cells to the particles was examined by light and transmission electron microscopy (LM and TEM), as well as by scanning electron microscopy (SEM), and compared to cells on control collagen surfaces without particles. Histological analysis of the samples revealed that the macrophages surrounded larger particles (18-20 m) and the cells appeared to be attached to the surface of the particles, and the smaller particles (4-10 m) had been phagocytosed within 2 h. Inflammatory cytokines (TNF-, IL-1, IL-1, and IL-6), lysosomal enzymes (-galactosidase and hexosaminidase), and prostaglandin E2 were released into the medium, and IL-1, IL-1, PGE2, -galactosidase, and hexosaminidase levels were significantly increased over collagen control values. The results demonstrate active phagochemotaxis by macrophages for wear particulates and validate this model as a means of studying the specific in vitro interactions of polyethylene with cells. J Biomed Mater Res, 39, 40-51, 1998.
Received: 8 July 1996; Accepted: 14 February 1997
*Correspondence to E. L. Boynton, Centre for Biomaterials, Department of Chemical Engineering, University of Toronto, Toronto, Canada
Funding Agency: Zimmer of Canada Inc. Funding Agency: Ontario Ministry of Health Trillium Fund and Career Scientific Award Program
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