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Osteoarthritis Pain Model Induced by Intra-Articular Injection of Mono-Iodoacetate in Rats
Published on: May 20, 2020
Monoiodoacetic acid induces arthritis and synovitis in rats in a dose- and time-dependent manner: proposed
1Department of Joint Surgery and Sports Medicine, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
Objective:
In a rat monoiodoacetic acid (MIA)-induced arthritis model, the amount of MIA commonly used was too high, resulting in rapid bone destruction. We examined the effect of MIA concentrations on articular cartilage and infrapatellar fat pad (IFP). We also established an original system for "macroscopic cartilage and bone score" and "IFP inflammation score" specific to the rat MIA-induced arthritis model.
Design:
Male Wistar rats received a single intra-articular injection of MIA in the knee. The amount of MIA was 0.1, 0.2, 0.5, and 1 mg respectively. Articular cartilage was evaluated at 2-12 weeks. IFP was also observed at 3-14 days.
Results:
Macroscopically, low MIA doses induced punctate depressions on the cartilage surface, and cartilage erosion proceeded slowly over 12 weeks, while higher MIA doses already induced cartilage erosion at 2 weeks, followed by bone destruction. MIA macroscopic cartilage and bone score, OARSI histological score, and Mankin score increased in a dose- and time-dependent manner. The IFP inflammation score peaked at 5 days in low dose groups, then decreased, while in high dose groups, the IFP score continued to increase over 14 days due to IFP fibrosis.
Conclusions:
Punctate depressions, cartilage erosion, and bone destruction were observed in the MIA-induced arthritis model. The macroscopic cartilage and bone scoring enabled the quantification of cartilage degeneration and demonstrated that MIA-induced arthritis progressed in a dose- and time-dependent manner. IFP inflammation scores revealed that 0.2 mg MIA induced reversible synovitis, while 1 mg MIA induced fibrosis of the IFP body.
Insights
Monoiodoacetic acid (MIA) arthritis models show dose-dependent cartilage and bone damage. Lower MIA doses cause reversible synovitis, while higher doses lead to significant bone destruction and infrapatellar fat pad fibrosis.
Area of Science:
- Orthopedics
- Rheumatology
- Animal Models
Background:
- The monoiodoacetic acid (MIA) induced arthritis model is widely used to study osteoarthritis.
- Standard MIA concentrations often lead to rapid and severe bone destruction, limiting detailed analysis of early-stage cartilage and fat pad changes.
- There is a need for refined models to better understand dose-dependent effects on joint tissues.
Purpose of the Study:
- To investigate the effects of varying monoiodoacetic acid (MIA) concentrations on articular cartilage and the infrapatellar fat pad (IFP) in a rat arthritis model.
- To develop and validate a novel scoring system for macroscopic cartilage, bone, and IFP inflammation.
- To establish a more controlled MIA-induced arthritis model for studying osteoarthritis progression.
Main Methods:
- Male Wistar rats received intra-articular injections of MIA at doses of 0.1, 0.2, 0.5, and 1 mg.
- Articular cartilage was assessed macroscopically and histologically from 2 to 12 weeks post-injection.
- Infrapatellar fat pad (IFP) inflammation was evaluated from 3 to 14 days post-injection using a specific scoring system.
Main Results:
- Lower MIA doses (0.1-0.2 mg) induced superficial cartilage lesions and reversible IFP synovitis.
- Higher MIA doses (0.5-1 mg) resulted in rapid cartilage erosion and bone destruction, with significant IFP fibrosis developing by 14 days.
- Established macroscopic cartilage and bone scores, and IFP inflammation scores, demonstrated a clear dose- and time-dependent progression of arthritis.
Conclusions:
- The study successfully established a dose-dependent MIA-induced arthritis model in rats.
- Macroscopic scoring systems provide a reliable method for quantifying cartilage degeneration and IFP inflammation.
- This refined model allows for the differentiation between reversible synovitis and progressive fibrosis, offering better insights into osteoarthritis pathogenesis.
