Exercise intervention increases expression of bone morphogenetic proteins and prevents the progression of cartilage-subchondral bone lesions in a post-traumatic rat knee model

• Published in: Osteoarthritis and cartilage Vol. 24; no. 6; pp. 1092 - 1102
• Main Authors: Iijima, H, Aoyama, T, Ito, A, Tajino, J, Yamaguchi, S, Nagai, M, Kiyan, W, Zhang, X, Kuroki, H
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2016
• Subjects: Animals; Bone micro-CT; Bone morphogenetic protein; Bone Morphogenetic Proteins; Cartilage; Cartilage, Articular; Exercise; Exercise Therapy; Male; Osteoarthritis; Rats; Rats, Wistar; Rheumatology; X-Ray Microtomography; Cartilage; Exercise; Bone morphogenetic protein; Bone micro-CT; Osteoarthritis
• ISSN: 1063-4584; 1522-9653
• DOI: 10.1016/j.joca.2016.01.006

Summary Objective This study aimed to determine whether treadmill walking (TW) prevents the progression of post-traumatic osteoarthritic changes in cartilage-subchondral bone unit, and whether the exercise timing changes the exercise efficacy in destabilized medial meniscus (DMM) rat knees. Design Twelve-week-old male Wistar rats underwent DMM surgery on their right knees and sham surgery on their left knees and were assigned to either the sedentary ( n  = 10) or walking ( n  = 24) groups. The rats in the walking group were subjected to TW from day 2 through 4 weeks, from 4 through 8 weeks, or from day 2 through 8 weeks ( n  = 8 per group). Osteoarthritic changes of cartilage and subchondral bone were assessed with micro-computed tomography, histology, and immunohistochemistry 8 weeks after surgery. Results TW prevented the progression of cartilage and subchondral bone lesions induced by the DMM, and increased bone morphogenetic protein (BMP)-2 and -6 expressions in superficial zone chondrocytes and bone-lining cells including osteoblasts. Furthermore, the TW-induced increase in BMPs varied with the exercise timing. Beginning TW 4 weeks after DMM surgery was the best option for increasing BMPs, coinciding with the most robust prevention of osteoarthritic changes. Conclusions TW increased the expression of BMPs and prevented the progression of cartilage-subchondral bone lesions in rat knees with a DMM. Selective exercise timing may be a key factor in the development of an exercise regimen for preventing the progression of post-traumatic osteoarthritis (PTOA). Furthermore, exercise may have favorable effects even after the PTOA has been developed.