Modulation of bone ingrowth and tissue differentiation by local infusion of interleukin‐10 in the presence of ultra‐high molecular weight polyethylene (UHMWPE) wear particles

Abstract Interleukin‐10 (IL‐10) is a cytokine that plays a major role in suppressing the inflammatory response, particulary cell‐mediated immunity that is characteristic of the TH1 response. The purpose of this study was to determine whether local infusion of IL‐10 could mitigate the suppression of bone ingrowth associated with polyethylene wear particles. Drug test chambers were implanted in the proximal tibia of 20 mature New Zealand white rabbits. The DTC provided a continuous 1 × 1 × 5‐mm canal for tissue ingrowth. After a 6‐week period for osseointegration, the DTC was then connected to an osmotic diffusion pump. IL‐10 at doses of 0.1–100 ng/mL (0.25 μL/h) was infused with or without ultra‐high molecular weight polyethylene particles (0.5 ± 0.2 μm diameter, 10¹² particles/mL) present in the chamber for a 3‐ or 6‐week period. The tissue in the chamber was harvested after each treatment; sections were stained with hematoxylin and eosin for morphometric analysis. Osteoclast‐like cells were identified by immunohistochemical staining using a monoclonal antibody directed against the alpha chain of the vitronectin receptor, CD51. Osteoblasts were identified using alkaline phosphatase staining. In dose–response studies, infusion of 1 ng/mL IL‐10 yielded the greatest bone ingrowth in the presence of particles. The addition of polyethylene particles evoked a marked foreign body reaction and fibrosis; bone ingrowth was significantly suppressed (p = 0.0003). Bone ingrowth was increased by over 48% with infusion of IL‐10 for the final 3 weeks of a 6‐week ultra‐high molecular weight polyethylene particle exposure compared with particles alone (p = 0.027). IL‐10 is a cytokine that plays a major role in suppressing the inflammatory response, especially cell‐mediated immunity that is characteristic of the TH1 response. Local infusion of immune‐modulating cytokines such as IL‐10 may prove to be useful in abating particle‐induced periprosthetic osteolysis. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 43–50, 2003