Figure 3 Human umbilical cord-derived mesenchymal stem cell (UC-MSC) treatment ameliorated inflammation in the interstitial cystitis (IC)-induced rat model. (A) (a–c): Hematoxylin and eosin staining; (d–f): Toluidine blue staining; (g–i): Masson’s trichrome staining. Hemorrhage, submucosal edema, vascular structure destruction (a–c) were more severe in the IC+PBS group, and recovered better in the IC+MSC group. The mast cell infiltration (white arrows in e and f) could be more easily observed in the IC+PBS group, compared with in the IC+MSC and sham groups. Tissue fibrosis (blue straining in g–i) was significantly decreased below the urothelium in the IC+MSC group (collagenous fiber, 24.52%) compared with in the IC+PBS group (collagenous fiber, 50.19%), but were similar to the sham group (collagenous fiber, 20.33%). Magnification ×200. (B) Comparison of histamine, 5-hydroxytryptamine (5-HT), and TNF-α among the 3 groups in bar charts. (C) Comparison of the number of infiltrating mast cells in the bladder of rats among the 3 groups in bar charts. ** P<0.01 vs sham group; ## P<0.01 vs IC+PBS group.