Fig. 4.

Characterization of MSCs and MSC-secreted exosomes. a Morphological observation of MSCs (100×). b Identification of surface marker molecules in MSCs using flow cytometry. c Osteogenic and adipogenic induction culture of MSCs (400×). (a) Osteogenic differentiation evaluated by alizarin red staining; (b) adipogenic differentiation evaluated by oil red O staining; (c) chondral differentiation-Alcian blue staining (200×). d Identification of exosomes by a transmission electron microscopy. e Detection of exosome diameter by dynamic light scattering. f Exosome surface markers CD63 and HSP70 measured using Western blot analysis; lane 1, extracted exosomes; lane 2, supernatant after extraction of exosomes. g The content of CD63, a surface marker in exosomes, detected using flow cytometry; *p < 0.05 vs. lane 1; measurement data were shown as mean ± standard error. The experiment was repeated three times to obtain the mean value