TNF‐α‐induced exosomal miR‐146a mediates mesenchymal stem cell‐dependent suppression of urethral stricture

• Published in: Journal of cellular physiology Vol. 234; no. 12; pp. 23243 - 23255
• Main Authors: Liang, Ying‐Chun, Wu, Yu‐Peng, Li, Xiao‐Dong, Chen, Shao‐Hao, Ye, Xiao‐Jian, Xue, Xue‐Yi, Xu, Ning
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.12.2019
• Subjects: Collagen; Cytokines; Enzyme-linked immunosorbent assay; Euthanasia; Exosomes; Fibroblasts; Fibrosis; Inflammation; Mesenchymal stem cells; Mesenchyme; miRNA; miR‐146a; Polymerase chain reaction; Stem cell transplantation; Stem cells; Stricture; TNF‐α; Transforming growth factor-b1; Tumor necrosis factor-TNF; Tumor necrosis factor-α; Ultrasound; Umbilical cord; Urethra; urethral stricture; urethral stricture; miR-146a; TNF-α; exosomes; mesenchymal stem cells
• ISSN: 0021-9541; 1097-4652; 1097-4652
• DOI: 10.1002/jcp.28891

The effective treatment of urethral stricture remains a medical problem. The use of proinflammatory cytokines as stimuli to improve the reparative efficacy of mesenchymal stem cells (MSCs) towards damaged tissues represents an evolving field of investigation. However, the therapeutic benefits of this strategy in the treatment of urethral stricture remain unknown. Here, we enriched exosomes derived from human umbilical cord‐derived MSCs pretreated with or without tumor necrosis factor alpha (TNF‐α) to evaluate their therapeutic effects in an in vivo model of TGFβ1‐induced urethral stricture. Male Sprague‐Dawley rats received sham (saline) or TGFβ1 injections to urethral tissues followed by incisions in the urethra. Animals in the TGFβ1 injection (urethral fibrosis) cohort were subsequently injected with vehicle control, or with exosomes derived from MSCs cultured with or without TNF‐α. After 4 weeks, rats underwent ultrasound evaluation and, following euthanasia, urethral tissues were harvested for histological and molecular analysis. In vitro, the effects of MSC‐derived exosomes on fibroblast secretion of collagen and cytokines were studied by enzyme‐linked immunosorbent assay (ELISA), quantitative real‐time polymerase chain reaction (qRT‐PCR), and western blot analysis. Exosomes derived from MSCs pretreated with TNF‐α were more effective in suppressing urethral fibrosis and stricture than exosomes from untreated MSCs. We found that miR‐146a, an anti‐inflammatory miRNA, was strongly upregulated in TNF‐α‐stimulated MSCs and was selectively packaged into exosomes. Moreover, miR‐146a‐containing exosomes were taken up by fibroblasts and inhibited fibroblast activation and associated inflammatory responses, a finding that may underlie the therapeutic mechanism for suppression of urethral stricture. Inhibition of miR‐146a in TNF‐α‐treated MSCs partially reduced antifibrotic effects and increased the release of proinflammatory factors of exosomes derived from these cells. Together these findings demonstrate that exosomes derived from TNF‐α‐treated MSCs are of therapeutic benefit in urethral fibrosis, suggesting that this strategy may have utility as an adjuvant therapy in the treatment of urethral stricture diseases. This study demonstrates that exosomes derived from MSCs primed with TNF‐α can suppress inflammatory responses and fibroblast activation, thereby significantly reducing urethral tissue fibrosis and urethral stricture. Mechanistically, TNF‐α‐mediated upregulation of miR‐146a in exosomes plays an important role in αMSC‐mediated tissue repair. Our current findings highlight potential new targets for the clinical treatment of stenosis and recurrence after urethrotomy.