Fig. 6

Scaffold/UC-MSCs transplantation facilitates collagen degradation in uterine scars via upregulation of MMP-9. a Masson’s trichrome staining of uterine scars at days 30 and 60 post-transplantation in the PBS group, the scaffold group, the UC-MSCs group and the scaffold/UC-MSCs group. Arrowheads indicate repair sites. Scale bars, 150 μm. b Immunohistochemical staining of matrix metalloproteinase-9 (MMP-9) in uterine scars at days 30 and 60 post-transplantation in the PBS group, the scaffold group, the UC-MSCs group and the scaffold/UC-MSCs group. Scale bars, 30 μm. Statistical analysis of the number of cells positive for MMP-9 counted from six randomly selected fields per section under a magnification of × 400. Data were presented as mean ± SEM. ^* P < 0.05 and ^** P < 0.01. c Uterine scars were transplanted with CM-Dil-labelled UC-MSCs or scaffold/UC-MSCs. At day 30 post-transplantation, uterine tissues containing the scarred areas were collected, embedded and sectioned. Cell nuclei were stained with DAPI (blue). UC-MSCs were tracked by the red fluorescence of CM-Dil. The sections were stained with anti-MMP-9 antibody and observed under a fluorescence microscope (green). Scale bars, 20 μm. d Western blot analysis of MMP-9 protein in cell lysates and culture medium of human endometrial stromal cells (hESCs), UC-MSCs in the monolayer culture (2D culture), UC-MSCs co-cultured with degradable collagen fibres (3D culture). Serum-free medium served as the negative control and Ishikawa cells served as the positive control. Blots were probed with β-actin and stained with Ponceau to ensure equal protein loading and transfer. PBS phosphate-buffered saline, UC-MSCs umbilical cord-derived mesenchymal stem cells