Fig. 3

GMSC and GMSCExo block migration to and invasion of the secondary implant. A H&E-stained negative control secondary cartilage showing no RASF invasion. B H&E-stained positive control secondary cartilage showing deep RASF penetration throughout the tissue including perichondrocytic degradation, blue arrows. C H&E-stained secondary cartilage section from a RASF-treated, GMSC exosome-injected mouse showing no RASF invasion. D H&E-stained RASF-treated and GMSC-treated secondary cartilage showing no RASF invasion. E Invasion depth demonstrates very deep penetration of the secondary cartilage when treated with RASF alone. Treatment with either GMSC or GMSCExo blocks RASF invasion of the cartilage in the secondary implant (mean ± SE, n = 5 for RASF alone 1°, 2° and negative control, n = 10 for RASF + GMSC and RASF, n = 13 for GMSCExo, *p < 0.05; **p < 0.01). F Close-up image showing extensive perichondrocytic degradation in the RASF-treated secondary location