Perianal and intestinal fistulae represent a frequent complication in up to 50% of patients with Crohn’s disease (CD) [1]–[3], one of the major types of inflammatory bowel diseases (IBD), and pose a challenging problem, since current treatment options such as administration of antibiotics [4], immunosuppressants or tumor necrosis factor alpha (TNF-α) antibodies often are insufficient to cure the complication and achieve complete fistula closure [5]–[8]. Here, TNF is linked to inflammatory bowel disease.