Fig. 4

FNDC5-OV/irisin ameliorated the paracrine dysfunction of BM-MSCs under hypoxia for 48 h. Representative ELISA assay illustrated the levels of VEGF (a), bFGF (b), IGF-1 (c), and HGF (d) in BM-MSCs under various groups. e Transmission electron micrograph of exosomes deprived from BM-MSCs. Cup-shaped structures, 30–100 nm in size, were identified as exosomes. Scale bar, 200 nm. f Representative Western blot analysis for the exosome markers Alix, CD63, and CD81 in exosomes. Semi-quantification of CD63 (g), CD81 (h), and Alix (i) expression. j NTA showed the concentration of the isolated exosomes derived from BM-MSCs and FNDC5-MSCs (n = 5). Data are expressed as the mean ± SEM; n = 5; *p < 0.05