BMSCs-Exos relieved cartilage damage and pain in OA rats. (A) Western blot analysis of COL2A1 and MMP13 protein levels (* compared with the control group, # compared with the IL-1β group). (B) In vivo imaging after intra-articular injection of exosome (Fluo, Fluorescence, BF, brightfield). (C) General morphology of the knee joint in rats. (D) Saffron solid green staining of the knee joint (scale = 50 μm). (E) OARSI scores among different groups. (F) ELISA of inflammatory factors in cartilage. (* compared with Sham group, # compared with OA group, n = 8 for each group). (G) PWT and PWL of rats at different time. (H) Immunofluorescence staining of CGRP and iNOS proteins in DRG tissues (scale = 200 μm, * compared with Sham group, # compared with OA group, n = 4 for each group). (I) A model of knee OA induced pain in rats. Reproduced under the terms of the CC-BY 4.0 [144]. Copyright 2020, The Authors, published by Springer Nature.