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

Authors

Naomasa Yokota, Takeo Kambayashi, Yu Tanabe

Published in

Orthopedics. Volume 49. Issue 4. Pages e351-e358. Epub Aug 14, 2026.

Abstract

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.
A total of 29 patients (33 knees) with KOA received 6 intra-articular injections of UC-EVs (1 × 10¹¹ 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.
Significant improvements in all KOOS subscale scores and VAS for pain were observed at all follow-up time points compared with baseline (P < .01), with all scores exceeding predefined minimal clinically important difference thresholds. 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.
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.

PMID:
42611014
Bibliographic data and abstract were imported from PubMed on 18 Aug 2026.

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