This article has an accompanying continuing medical education activity, also eligible for MOC credit, on page e9. Learning Objective-Upon completion of this activity, successful learners will be able to list risk factors for postoperative recurrence in Crohn's disease; list appropriate strategies to evaluate for early disease recurrence following surgery for Crohn's disease; and outline treatment options to reduce risk of postoperative recurrence in Crohn's disease, and strategies if early recurrence is identified. BACKGROUND AND AIMS: Different types of histologic lesions at the ileal margin, detected by histology, have been associated with increased rates of recurrence after ileocaecal surgery in patients with Crohn's disease (CD). We aimed to characterize histologic features of the ileal margin and to evaluate their association with disease recurrence. METHODS: We collected histologic data from 211 patients with ileal or ileocolonic CD who underwent ileocolonic resections at hospitals in France from September 2010 through December 2016. Ileal margins were analyzed. Early endoscopic recurrence was defined by a Rutgeerts score of i2 or more, 6 months after surgery. We also collected data from 10 adults with healthy ileum who underwent ileocecal resection for colonic tumors (controls). Clinical relapse was defined by CD-related symptoms confirmed by imaging, endoscopy, therapy intensification, CD-related complication, or subsequent surgery. RESULTS: Six months after surgery, 49% of patients had endoscopic recurrence; 5 years after surgery, 57% of patients had clinical relapse. Ileal margins were macroscopically affected in 20.9% of patients. CD transmural lesions at the margin (defined by mucosal ulceration or cryptitis, submucosal fibrosis and lymphoplasmacytic infiltrate of the subserosa) were observed in 13.6% of patients. Endoscopic recurrence was observed in 75% of patients with CD transmural lesions vs 46% of patients without (P [.005). In multivariate analysis, CD transmural lesions at the margin were independently associated with early endoscopic recurrence (OR, 3.83; 95% CI, 1.47-11.05; P [.008) and clinical recurrence (OR 2.04; 95% CI, 1.09-3.99; P [.026). CONCLUSION: In patients with CD, transmural lesions at the ileal margin were associated with an increased risk of post-operative recurrence. Histologic features of the ileal margin should be included in making decisions about post-operative therapy.

Tissue engineering appears promising as an alternative technique for esophageal replacement. Mesenchymal stem cells (MSCs) could be of interest for esophageal regeneration. Evaluation of the ability of an acellular matrix seeded with autologous MSCs to promote tissue remodeling toward an esophageal phenotype after circumferential replacement of the esophagus in a mini pig model. A 3 cm long circumferential replacement of the abdominal esophagus was performed with an MSC-seeded matrix (MSC group, n = 10) versus a matrix alone (control group, n = 10), which has previously been matured into the great omentum. The graft area was covered with an esophageal removable stent. A comparative histological analysis of the graft area after animals were euthanized sequentially is the primary outcome of the study. Histological findings after maturation, overall animal survival, and postoperative morbidity were also compared between groups. At postoperative day 45 (POD 45), a mature squamous epithelium covering the entire surface of the graft area was observed in all the MSC group specimens but in none of the control group before POD 95. Starting at POD 45, desmin positive cells were seen in the graft area in the MSC group but never in the control group. There were no differences between groups in the incidence of surgical complications and postoperative death. In this model, MSCs accelerate the mature re-epitheliazation and early initiation of muscle cell colonization. Further studies will focus on the use of cell tracking tools in order to analyze the becoming of these cells and the mechanisms involved in this tissue regeneration.