hWJMSC-MVs alleviate the renal fibrosis in injured kidney tissues and improve renal functions after two weeks. (A) Representative micrographs of Masson’s tri-chrome staining in tubular interstitial areas. Ischemic injury caused a progressive increase in positive-staining collagen deposition, whereas the MVs group had a remarkable reduction in collagen deposition. (The original magnification is 400×, Scale bar = 50 um). (B) Fibrosis score. The highest fibrosis score was achieved by the vehicle group, whereas the MV group had a significantly lower score. The score was obtained by the addition of all scores for collagen staining from 30 random high power fields with a maximum score of 300. All quantitative data are shown as mean ± SD of six kidney samples for each experimental condition. (n = 6, *P <0.05, sham versus vehicle; #P <0.05, MVs versus vehicle, **P <0.05, sham versus MVs). (C, D) Serum creatinine and BUN levels were measured at the indicated times after injury in the sham, vehicle and MVs groups. The right uninjured kidneys of rats were removed on Day 12, and serum samples collected at different times. Values are the mean ± SD of data with six animals in each group (n = 6, *P <0.05, sham versus vehicle; #P <0.05, MVs versus vehicle). hWJMSC-MVs, human Wharton-Jelly MSCs derived microvesicles.