Arthritis Model

Model Introduction

Osteoarthritis (OA) is a class of chronic degenerative diseases characterized by articular cartilage degeneration, subchondral bone changes, and synovial inflammation. Recent studies suggest that OA is not a single disease but exists in different phenotypes, including:

• Traumatic OA
• Metabolic OA
• Aging-related OA
• Genetic OA
• Pain-related OA Different phenotypes exhibit significant differences in pathological mechanisms and treatment responses; therefore, reasonable and stable animal models must be established based on phenotypic characteristics.

Research Applications

OA animal models can be used to:

• Study the pathological mechanisms of different OA phenotypes.
• Evaluate chondroprotective and repair treatments.
• Explore the roles of inflammatory cytokines and metabolic abnormalities.
• Study age-related OA progression.
• Evaluate the efficacy of analgesic and anti-inflammatory drugs. Phenotypic modeling helps improve research precision.

Experimental Design Key Points

I. Traumatic OA Model

(A) Invasive Induction Methods

1. ACLT (Anterior Cruciate Ligament Transection)
   • Simple operation, minimal structural damage.
   • Progression is slower than MMT, suitable for pharmacological research.
   • Evaluated using Mankin or OOCHAS scores.
   • Vibration or weight-bearing training can accelerate model progression.
2. MMT (Medial Meniscal Transection)
   • Faster progression than ACLT.
   • Commonly used for short-term studies.
   • Can simulate early OA within 4 weeks.
3. Modified Hulth Method
   • Retains part of the ligaments.
   • High success rate.
   • Forced exercise can shorten the cycle.
4. Closed Joint Scoring/Groove Method
   • Minimal trauma.
   • Suitable for early OA research.

(B) Non-invasive Induction Methods

1. Intra-articular Tibial Plateau Fracture Method
   • Controlled impact force.
   • Applicable for acute injury research.
2. Cyclic Joint Compression Method
   • Simulates chronic overuse.
   • Different loads produce different levels of severity.
3. Tibial Compression Overload Method
   • Single high-energy impact.
   • Suitable for early OA research.

II. Metabolic OA Model

1. High-Fat Diet Model
   • Does not destroy joint stability.
   • Close to the mechanism of obesity-related OA.
   • Usually requires approximately 20 weeks for modeling.
2. Ovariectomy Model
   • Simulates estrogen imbalance.
   • Can be combined with exercise to accelerate progression.
   • CTX-I and CTX-II are associated with degeneration.

III. Aging-Related OA Model

1. Natural Aging Model
   • Hartley guinea pigs are commonly used.
   • Pathologically similar to humans.
2. Anti-aging Gene Knockout Model
   • e.g., SIRT1 knockout.
   • Can be combined with ACLT+MMT to establish advanced-age models.

IV. Genetic OA Model

Relevant genes include:

• Col11a1, Col2a1, Del1
• Type II and Type IX collagen
• Copper transport genes
• MMP-13, BMP-1a receptor, ADAM-15, MMP-14
• IL-6, Mig-6, A-1 integrin
• Fibromodulin, Biglycan, etc. Suitable for genetic mechanism research and efficacy evaluation.

V. Pain-Related OA Model

(A) Intra-articular Injection Method

1. Monosodium Iodoacetate (MIA)
   • Inhibits the Krebs cycle.
   • Induces chondrocyte apoptosis.
   • Pain severity correlates with dose and time.
   • Classic pain model.
2. Papain
   • Induces cartilage destruction.
   • Early OA forms in 4–6 weeks.
3. Collagenase
   • Degrades cartilage matrix.
   • Pathological changes visible in 3 days.

(B) Cold Stimulation Method

• 4°C fixation.
• Cartilage damage appears after 6 weeks.
• Elevated levels of IL-1β, TNF-α, etc.

(C) Blood Circulation Blockage Method

• Vein ligation.
• Early to mid-stage OA forms in 8 weeks.

Key Detection Indicators

• Cartilage histological scores (Mankin, OOCHAS).
• Subchondral bone changes.
• Inflammatory cytokines (IL-1β, TNF-α, etc.).
• CTX-I, CTX-II.
• Imaging evaluation.
• Pain behavioral assessment.