Fig. 2
![Fig. 2](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs13287-021-02481-9/MediaObjects/13287_2021_2481_Fig2_HTML.png)
Effect of MSC-EVs on meniscus regeneration. A Histological and immunohistochemical (IHC) staining of regenerated menisci with or without MSC EV treatment. Samples were stained with HE, safranin-O/fast green, type II collagen (Col II), and type I collagen (Col I) (n = 6; 3 weeks). B Semiquantitative evaluation of meniscus regeneration by modified Pauli’s score. C Quantitative evaluation of the safranin-O-positive area by ImageJ. Three sections per knee were evaluated. Data are the means ± SD. *P < 0.05 according to the Mann-Whitney U test