Characteristics of the Mucosal Surface on Scanning Electron Microscopy in Patients with Remitting Ulcerative Colitis

Background: Ulcerative colitis (UC) is characterized by chronic intestinal epithelial damage, and previous studies have evaluated the epithelial structure of patients with active UC using electron microscopy. Aims: This study aimed to assess the intestinal epithelial structure using scanning electron microscopy (SEM) and the features of patients with UC who are in remission. Methods: In total, eight healthy controls and 20 patients with UC were enrolled, and colonic tissue samples from the cecum and rectum were collected. Then, we compared the epithelial surface structure on SEM between patients with UC who are in clinical remission and healthy controls. Results: In healthy controls, the colonic surface comprises small lobes (termed units), with one crypt located in the middle of each unit. In patients with UC, we found irregular unit and crypt mouth size, double crypt sign (> 1 crypt per unit), and lower number of small vesicles in the intestinal epithelial cells. Compared with healthy controls, patients with UC often presented with irregular unit size, double crypt sign, and irregular crypt mouth size in the rectum. The small vesicles were observed less frequently in patients with UC than in healthy controls. Conclusions: SEM revealed a unique epithelial structure in patients with UC who are in remission.