Fig. 5

W-Exo-L@GelMA shows a significant joint retention effect and attenuates cartilage lesions in the OA murine model. A Joint retention assessed by in vivo fluorescence method. The hydrogel with Cy5-loaded exosomes or the Cy5-loaded exosomes alone was injected into the knee joint of the 12-week-old C57BL/6 mice. W-Exo-L@GelMA delayed the dissipation of the Cy5 fluorescence signal, indicating that the hydrogel can be retained 14 days after injection. Data represent mean ± SD; N = 3/group. **P < 0.01 by Student’s t-test; the colored groups versus Exo-L@GelMA. #P < 0.05; ##P < 0.01 by Student’s t-test, the colored groups versus W-Exo-L@GelMA; $P < 0.05 by Student’s t-test, W-Exo-L@GelMA versus Exo-L@GelMA. B Safranin O-fast green staining of knee sections. W-Exo-L@GelMA exhibited a stronger ability to attenuate cartilage wear and degeneration induced by destabilization of the medial meniscus (DMM) than L@GelMA, Exo@GelMA, or Exo-L@GelMA. Scar bar: 200 μm. C Immunohistochemistry representative images of aggrecan protein levels. Scar bar: 200 μm. Aggrecan expression was increased in local chondrocytes after the intervention, especially W-Exo-L@GelMA. D Immunohistochemistry representative images of MMP13 protein levels. Scar bar: 200 μm. The expression of MMP13 in local chondrocytes decreased after treatments. E Statistical analysis of OARSI histological scores. Data represent mean ± SD; N = 6/group. *P < 0.05; **P < 0.01 by one-way ANOVA. ##P < 0.01 by one-way ANOVA, the DMM group versus the control group. F Quantitative statistics of immunohistochemistry analyses of aggrecan and MMP13. Data represent mean ± SD; N = 6/group. *P < 0.05; **P < 0.01 by one-way ANOVA. ##P < 0.01 by one-way ANOVA, the DMM group versus the control group