Exosome therapy for knee osteoarthritis: a network meta-analysis based on rat models

To compare the therapeutic effects of exosomes from different cell sources and doses in rat knee osteoarthritis models using network meta-analysis, and to identify potential optimal strategies for preclinical optimization and clinical hypothesis generation.

A systematic search of PubMed, Web of Science, Embase, and Scopus identified 27 eligible randomized controlled trials (456 rats). Traditional random-effects meta-analysis and frequentist network meta-analysis were conducted. Treatments were ranked using SUCRA values.

A total of 27 studies were included, comprising 456 rats. Traditional meta-analysis revealed that exosome therapy significantly reduced joint cartilage histopathological damage (reduced OARSI score: SMD = -3.78, 95% CI: -4.76, -2.80), promoted type II collagen synthesis (SMD = 3.41, 95% CI: 1.87, 4.95), and suppressed the expression of the inflammatory cytokine IL-1β (SMD = -3.26, 95% CI: -4.08, -2.44). Network meta-analysis further indicated that under high-dose conditions (≥100 μg), exosomes derived from human amniotic fluid stem cells (hAFSCs-Exo) and human umbilical cord mesenchymal stem cells (hUCMSCs-Exo) ranked highest in relative efficacy for improving the OARSI score. hUCMSCs-Exo also demonstrated the most potent anti-inflammatory effect by reducing IL-1β. Overall, exosome therapy exhibited a dose-related trend in efficacy, with high-dose transplantation showing higher probabilistic SUCRA rankings across most outcome measures. However, assessment of publication bias revealed marked asymmetry; after trim-and-fill correction, the effect size for type II collagen expression decreased from SMD = 3.41 to 1.26, suggesting that the magnitude of the treatment effect may have been overestimated. This overestimation reduces the certainty of the observed treatment effects. Despite the presence of publication bias and methodological limitations, the main conclusions remained statistically robust after trim-and-fill correction.

Current evidence from rat models suggests that exosome therapy may substantially ameliorate the pathological progression of KOA, with exosomes derived from early developmental tissues, particularly hAFSCs-Exo and hUCMSCs-Exo, showing favorable chondroprotective and anti-inflammatory effects in the probabilistic ranking when administered at high doses. Nevertheless, the findings from publication bias and trim-and-fill analyses indicate that the existing effect sizes are likely overestimated. These results require confirmation in larger-scale, methodologically more rigorous preclinical studies.