Abstract| Volume 28, SUPPLEMENT 1, S16, April 2020

Additional Use of Synovial Mesenchymal Stem Cell Transplantation Following Surgical Repair of a Complex Degenerative Tear of the Medial Meniscus of the Knee

      Purpose: Complex degenerative tears of the medial meniscus in the knee are usually treated using meniscectomy. However, this procedure increases the risk of osteoarthritis, while other treatments aimed at meniscal repair remain challenging due to the high possibility of failure. The use of synovial mesenchymal stem cells (MSCs) is an attractive additional approach for meniscal repair, as these cells have high proliferative and chondrogenic potential. We surgically repaired a complex degenerative tear of the medial meniscus and then transplanted autologous synovial MSCs. We evaluated clinical outcomes at two years and assessed adverse events.
      Methods: We enrolled patients with clinical symptoms that included a feeling of instability in addition to pain caused by their complex degenerative tears of the medial meniscus. Two weeks after surgical repair of the torn meniscus, autologous synovial MSCs were transplanted onto the menisci of five patients.
      Results: The total Lysholm knee score, the Knee Injury and Osteoarthritis Outcome Scale (KOOS) scores for “pain,” “daily living,” “sports activities,” and the numerical rating scale were significantly increased after two years. Three adverse events, an increase in c-reactive protein (CRP), joint effusion, and localized warmth of the knee were recorded, although these could have been due to the meniscal repair surgery.
      Conclusions: This first-in-human study confirmed that the combination of surgical repair and synovial MSC transplantation improved the clinical symptoms in patients with a complex degenerative tear of the medial meniscus. No adverse events occurred that necessitated treatment discontinuation. After this clinical study, we started a clinical trial.