Safety and Efficacy of Intra-Articular Injection of Umbilical Cord-Derived Extracellular Vesicles in Patients With Knee Osteoarthritis: A Retrospective Study

BACKGROUND: Extracellular vesicles derived from the umbilical cord (UCEVs) have emerged as a potential biological therapy for knee osteoarthritis (KOA). However, their clinical efficacy remains unknown. The purpose of this study was to evaluate the safety and efficacy of intra-articular injections of umbilical cord stem cell-derived UC-EVs in patients with KOA. MATERIALS AND METHODS: particles per dose) every 2 weeks. Clinical outcomes were assessed at 3, 6, and 12 months using the Knee Injury and Osteoarthritis Outcome Score (KOOS), visual analog scale (VAS), and Outcome Measures in Rheumatology and Osteoarthritis Research Society International (OMERACT-OARSI) responder criteria. VAS for pain decreased by a mean of 38.8 ± 25.5 mm, and the greatest KOOS improvement was seen in quality of life (32.8 ± 21.9) and sport and recreation function (28.6 ± 25.2). The OMERACT-OARSI responder rate was 66.7% overall (22/33 knees), with rates of 83.3%, 66.7%, and 44.4% for Kellgren-Lawrence grades 2, 3, and 4, respectively. No serious adverse events were observed. CONCLUSION: Intra-articular injection of UC-EVs demonstrated meaningful clinical benefits in patients with KOA, including reductions in VAS pain scores and improvements across all KOOS domains. Patients with Kellgren-Lawrence grade 2 or 3 showed greater treatment responses compared with grade 4. These findings suggest that intra-articular UC-EVs therapy may represent a promising next-generation treatment option for KOA.