NRF2-overexpressing mesenchymal stem cells support epithelial barrier repair and mucosal tissue recovery in experimental colitis.

Ulcerative colitis is characterized by oxidative stress, epithelial barrier dysfunction and persistent mucosal injury. Mesenchymal stem cells (MSCs) have barrier-supportive and tissue-reparative properties, but oxidative inflammatory conditions may impair their survival and functional activity. Nuclear factor erythroid 2-related factor 2 (NRF2) is a central regulator of cellular antioxidant responses and may improve MSC adaptation to oxidative stress. Here, stable NRF2-overexpressing MSCs (MSCs-NRF2) were generated by lentiviral transduction and evaluated in an H2O2-induced Caco-2/HT-29 epithelial injury model and a dextran sulfate sodium (DSS)-induced acute colitis mouse model. qRT-PCR, immunofluorescence staining, transcriptomic analysis and 16S rRNA sequencing were used to assess oxidative-stress responses, epithelial barrier restoration, mucosal injury and microbial alterations. NRF2 overexpression enhanced antioxidant and anti-inflammatory gene expression in MSCs and improved MSC viability under oxidative stress. Conditioned medium from MSCs-NRF2 more effectively supported ZO-1 and occludin recovery in injured epithelial co-cultures than conditioned medium from control MSCs. In DSS-induced colitis, MSCs-NRF2 were associated with reduced mucosal injury, improved tight-junction and mucus-barrier markers, and altered gut microbial profiles. These responses were accompanied by increased NRF2-related antioxidant signalling in intestinal tissue. These findings indicate that NRF2 overexpression strengthens MSC adaptation to oxidative inflammatory stress and supports epithelial barrier repair and mucosal tissue recovery in experimental colitis.