Abstract
Mesenchymal stem cells (MSCs) are pluripotent cells that can be applied to the treatment of immune disorders, including inflammatory bowel disease (IBD). The therapeutic effects of MSCs have been mostly attributed to the secretion of soluble factors with paracrine actions, such as extracellular vesicles (EVs), which may play a relevant role in the repair of damaged tissues. In the present study, a mouse model of colitis was induced with the use of trinitrobenzene sulfonic acid (TNBS). EVs derived from human placental mesenchymal stem cells (hP‑MSCs) were used for the treatment of colitis by in situ injection. Clinical scores were applied to verify the therapeutic effects of EVs on mice with colitis. Inflammation in the colon was evaluated by measuring the levels of various inflammatory cytokines. The content of reactive oxygen species (ROS) was detected by the use of molecular imaging methods for real‑time tracking and the therapeutic effects of EVs on mucosal healing in mice with colitis were evaluated. The results revealed that the injection of EVs regulated the balance of pro‑inflammatory and anti‑inflammatory cytokines in colon tissue. Treatment with EVs also suppressed oxidative stress by decreasing the activity of myeloperoxidase (MPO) and ROS. Histological analysis further confirmed that the EVs significantly promoted mucosal healing, as reflected by the promotion of the proliferation of colonic epithelial cells and the maintenance of tight junctions. Taken together, the findings of the present study demonstrated that EVs derived from hP‑MSCs alleviated TNBS‑induced colitis by inhibiting inflammation and oxidative stress. These findings may provide a novel theoretical basis for the EV‑based treatment of IBD.