Osteoarthritis Rat Model and Isorhy Treatment

The destabilized medial meniscus (DMM) model was used to mimic OA. 15 four-week-old male Sprague Dawley rats (200–250 g) were correctly partitioned into three portions: Normal group, OA group (surgery; normal saline treatment on the Monday of every week from the 5th to the 8th week after surgery) and OA + Isorhy group (surgery; 50 μM Isorhy treatment on the first day of every week from the 5th to the 8th week after surgery). After 4 weeks of drug treatment, all animals were euthanized through CO₂ induction. Then the rats had been processed without debridement of the knee specimens and fixed using 4% paraformaldehyde for two days. This study was conducted according to the NIH guidelines (NIH Pub No 85-23, revised 1996) and the Chinese Regulations for the Management of Laboratory Animals, and followed the Guide for the Care and Use of Laboratory Animals published by the National Institutes of Health (NIH) in 2011, which has already been permitted through the ethics committee of the Second Affiliated Hospital of Jiaxing University.