Due to a dysfunctional mucosal barrier, bacteria can invade the gut mucosa and thereby trigger excessive immune responses that lead to inflammation of the intestines.57,58 MSCs can promote the expression of the tight junction proteins claudin-1 and ZO-1 and thus improve the intestinal barrier function, which endows cell therapies based on MSCs with a unique ability to support the intestinal barrier of patients with IBD.59 Intestinal barrier recovery may induce changes in the microbiota and metabolites. The gene discussed is CLDN1; the disease is inflammatory bowel disease.