Proliferation and migration of human NP cells treated with exosomes. (A) Light microscopy images of the scratch wound assay (scale bar, 100 µm) and (B) quantified migration distance indicating that ADSC-derived exosomes significantly stimulated the migration rate of human NP cells. (C) The Cell Counting Kit-8 assay demonstrated that the proliferation rate of human NP cells grown with ADSC-derived exosomes was higher than that in the control group. *P<0.05 vs. 0 h. NP, nucleus pulposus; ADSC, adipose-derived stem cell; Ctrl., control; Expe., experimental; OD, optical density.