Mesenchymal stem cell-derived exosomes derived from induced pluripotent stem cells ameliorate inflammation and promote mucosal healing via miR-34a-5p in Crohn disease.

Abstract

Background: Crohn disease (CD) is a chronic, recurrent inflammatory bowel disease. Mesenchymal stem cell-derived exosomes (MSC-Exos) have emerged as promising cell-free treatments for CD.

Objective: In this study we aimed to investigate the therapeutic effect and potential mechanisms of MSC-Exos derived from induced pluripotent stem cells (iPSCs) (iPSC-MSC-Exos) in patients with colitis.

Methods: iPSC-MSC-Exos were administered intraperitoneally to mice with trinitrobenzene sulfonic acid (TNBS)-induced colitis. The colonic stem cell markers Lgr5 and Bmi1, and the proliferation marker Ki-67 were assessed by immunofluorescence. Lamina propria mononuclear cells (LPMCs) were isolated from the mouse colons and analyzed by flow cytometry. Furthermore, microarray analysis was performed to identify the differential expression of micro RNAs (miRNAs) in the iPSC-MSC-Exos. iPSC-MSC-Exos with micro RNA (miR)-34a-5p overexpression (Exo-OE) or knockdown (Exo-KD) were used to treat colitis in the mice. The candidate targets of miR-34a-5p and its downstream signaling pathways were confirmed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting.

Results: The iPSC-MSC-Exos migrated to the inflamed colon and protected the colon stem cells against inflammatory damage, promoted epithelial cell proliferation, and decreased the infiltration of proinflammatory Th1/9/17, CD4 +  tumor necrosis factor alpha (TNF-α)+, and macrophage cells while increasing anti-inflammatory T-regulatory (Treg) and B-regulatory (Breg) cells to alleviate TNBS-induced colitis in the mice. The therapeutic effect was sustained for 7 days after a single injection. MiR-34a-5p Exo-OE magnified this effect, whereas Exo-KD abolished it. The iPSC-MSC-Exos also inhibited the proliferation and migration of CD4 + LPMCs isolated from patients with CD. The miR-34a-5p expression was significantly elevated in the iPSC-MSC-Exos, which inhibited PPP2R3A expression by directly targeting its 3' untranslated region (3'-UTR). MiR-34a-5p Exo-OE significantly decreased the expression of PPP2R3A while increasing the expression of the Wingless-related integration site (Wnt) signaling ligands of β-catenin (Wnt/β-catenin signaling) and CD44.

Conclusions: iPSC-MSC-Exos ameliorated colitis and promoted mucosal healing in a TNBS-induced CD-like model by activating Wnt/β-catenin signaling via miR-34a-5p, which targets PPP2R3A.