Recently, the Affiliated Hospital of Zhejiang University School of Medicine, with the cooperation of Zhejiang University School of Medicine and other research units, completed an autologous cartilage transplantation for a 17-year-old patient with cartilage loss in the knee, and the patient became one of the first patients in China to receive autologous cartilage transplantation in vitro culture to “repair” the cartilage defect. Seventeen-year-old Jie suddenly felt a twist in his left knee during a basketball game. Six months later, he felt pain in his knee and went to the hospital for a CT examination, which revealed that a walnut-sized piece of cartilage had fallen out of the femoral condyle of Jie’s knee joint and was free in the knee joint. The doctor analyzed that Jie’s sprain had caused cartilage damage, and that the constant wear and tear of the movement had led to a larger and larger area of cartilage loss. Xuesong Dai, Department of Orthopedics, The Second Hospital of Zhejiang University School of Medicine If this disease occurs in adults, in very serious cases, doctors may recommend replacing the artificial joint to achieve the purpose of walking again. But because Jie’s epiphysis has not yet closed, it means that Jie’s development is not yet complete, which is a contraindication to joint replacement; and a traditional treatment method called “microfracture” is not very effective. According to Dr. Dai Xuesong, director of the Department of Orthopedics at the Second Hospital of Zhejiang University, foreign countries have been doing research on chondrocyte regeneration, targeting patients like Xiao Jie. At present, Zhejiang University School of Medicine Professor Ouyang Hongwei and other researchers, has studied a new technology for the treatment of cartilage injury – tissue-engineered cartilage transplantation (MACI). By harvesting the patient’s own cartilage cells, the patient is successfully cultured in vitro and then “patched” back to the patient. Prof. Ouyang Hongwei and Dr. Xuesong Dai, the chief physician, evaluated Jie and decided that this technique could be tried to change his condition. In the first surgery, Dr. Dai used an arthroscope to remove the cartilage that had fallen out, and then took a few pieces of normal cartilage around the cartilage defect in Jie’s knee the size of a grain of rice, which they would use as seeds to grow new cartilage. However, the human body is an extremely complex tissue, and it is difficult to simulate the human environment to let the cells grow out. The researchers cut up the rice-sized cartilage tissue and treated it with special enzymes, then collected the cells and placed them in a special cell culture medium, which was kept in a CO2 incubator at 37 degrees Celsius, where the culture medium was regularly changed and the cells were spot-checked. This simulates the metabolism of tissues in vivo. The scattered newborn cells gather on a scaffold called gelatinous material. The scaffold is like a blanket, and a single chondrocyte, which will comfortably lie in the gaps of the carpet, forms cartilage. This scaffold crawling with cells, like cloth, can be cut and stitched, which gives clinicians more room to maneuver. A few days ago, this precious piece of newborn cartilage was escorted to the Second Hospital of Zhejiang Hospital, where Dr. Xuesong Dai, the chief surgeon, personally took the lead and precisely transplanted the trimmed regenerated cartilage to the defective joint surface through a small, minimally invasive incision.