Effects of in vivo cyclic compressive loading on the distribution of local Col2 and superficial lubricin in rat knee cartilage

• Published in: Journal of orthopaedic research Vol. 39; no. 3; pp. 543 - 552
• Main Authors: Ji, Xiang, Ito, Akira, Nakahata, Akihiro, Nishitani, Kohei, Kuroki, Hiroshi, Aoyama, Tomoki
• Format: Journal Article
• Language: English
• Published: United States 01.03.2021
• Subjects: ADAMTS5 Protein - metabolism; Animals; cartilage degeneration; Cartilage, Articular - physiology; Chondrocytes - physiology; Collagen Type II - metabolism; in vivo cyclic compression; Knee Joint - physiology; Male; Matrix Metalloproteinase 13 - metabolism; post‐traumatic osteoarthritis; Proteoglycans - metabolism; Random Allocation; rat model; Rats; Rats, Wistar; superficial lubricin; type II collagen; Weight-Bearing; type II collagen; cartilage degeneration; rat model; post-traumatic osteoarthritis; in vivo cyclic compression; superficial lubricin
• ISSN: 0736-0266; 1554-527X; 1554-527X
• DOI: 10.1002/jor.24812

This study aimed to examine the effects of an episode of in vivo cyclic loading on rat knee articular cartilage (AC) under medium‐term observation, while also investigating relevant factors associated with the progression of post‐traumatic osteoarthritis (PTOA). Twelve‐week‐old Wistar rats underwent one episode comprising 60 cycles of 20 N or 50 N dynamic compression on the right knee joint. Spatiotemporal changes in the AC after loading were evaluated using histology and immunohistochemistry at 3 days and 1, 2, 4, and 8 weeks after loading (n = 6 for each condition). Chondrocyte vitality was assessed at 1, 3, 6, and 12 hours after loading (n = 2 for each condition). A localized AC lesion on the lateral femoral condyle was confirmed in all subjects. The surface and intermediate cartilage in the affected area degenerated after loading, but the calcified cartilage remained intact. Expression of type II collagen in the lesion cartilage was upregulated after loading, whereas the superficial lubricin layer was eroded in response to cyclic compression. However, the distribution of superficial lubricin gradually recovered to the normal level 4 weeks after loading‐induced injury. We confirmed that 60 repetitions of cyclic loading exceeding 20 N could result in cartilage damage in the rat knee. Endogenous repairs in well‐structured joints work well to rebuild protective layers on the lesion cartilage surface, which may be the latent factor delaying the progression of PTOA. This study investigated the appropriate cyclic compression loading approach associated with the progression of post‐traumatic osteoarthritis on Rat model, and newly found localized type II collagen upregulated within 3 days after loading and superficial lubricin decreased immediately after damage yet recovered gradually to the normal level.