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Polymorphonuclear leukocyte degranulation with exposure to polymethylmethacrylate nanoparticles
1Department of Orthopaedics, University of Illinois, College of Medicine, Chicago 60680.
Abstract:
Polymethylmethacrylate (PMMA) is clinically employed in a wide range of orthopaedic procedures. The etiology of the inflammatory reaction of recipient tissues to PMMA remains unresolved. Classically, polymorphonuclear leukocytes (PMNs) release cytoplasmic lysosomal granules when exposed to a variety of proinflammatory stimuli. Such degranulation contributes, and partially defines, the local tissue reaction to this foreign material. In the present investigation, PMMA particles (50-60 nm) were mixed with human PMNs, and the amount of lactate dehydrogenase, lysozyme, and beta-glucuronidase released from the cells was quantitated. In all cases, a dose-dependent increase in degranulation followed the addition of increasing amounts of PMMA to the PMNs. In addition, the migration of PMNs was diminished in a dose-dependent manner with exposure to increasing amounts of the cement. These results suggested that PMMA stimulates the release of leukocyte lysosomal contents and alters the migration characteristics of these cells in a manner that is consistent with the local inflammatory reaction to this cement.
Insights
Polymethylmethacrylate (PMMA) cement triggers inflammatory responses by causing polymorphonuclear leukocytes (PMNs) to release lysosomal contents. This study shows PMMA particles increase PMN degranulation and decrease their migration, explaining tissue reactions.
Area of Science:
- Biomaterials Science
- Immunology
- Orthopaedic Surgery
Background:
- Polymethylmethacrylate (PMMA) is widely used in orthopaedic surgery.
- The inflammatory reaction to PMMA in tissues is not fully understood.
- Polymorphonuclear leukocytes (PMNs) are key immune cells involved in inflammatory responses.
Purpose of the Study:
- To investigate the effect of PMMA particles on human PMNs.
- To determine if PMMA induces degranulation and affects PMN migration.
- To elucidate the cellular mechanisms behind PMMA-induced inflammation in orthopaedics.
Main Methods:
- Human PMNs were incubated with varying concentrations of PMMA particles (50-60 nm).
- Release of lactate dehydrogenase, lysozyme, and beta-glucuronidase from PMNs was measured.
- PMN migration assays were performed following exposure to PMMA.
Main Results:
- PMMA particles caused a dose-dependent increase in the release of lysosomal enzymes from PMNs.
- Exposure to increasing amounts of PMMA significantly reduced PMN migration.
- These findings indicate PMMA directly stimulates inflammatory cell responses.
Conclusions:
- PMMA particles stimulate the degranulation of human PMNs, releasing inflammatory mediators.
- PMMA alters PMN migration, potentially contributing to the foreign body response.
- Understanding these cellular interactions is crucial for managing PMMA-related inflammation in orthopaedic implants.