Mucosal Recovery after Intestinal Transplantation in the Rat: A Sequential Histological and Molecular Assessment.

Introduction: Intestinal cold ischemia and subsequent reperfusion during transplantation result in various degrees of mucosal injury ranging from mild edema to extensive mucosal loss. Mucosal barrier impairment favors bacterial translocation and fluid loss and raises nutritional challenges. The injured intestine also releases proinflammatory mediators and upregulates various epitopes toward an inflammatory phenotype. We studied the process of mucosal injury and repair during the early period after intestinal transplantation from a histological and molecular standpoint. Materials and Methods: Adult Sprague-Dawley rats were used as donors and recipients. Donor intestines were perfused and stored in saline for 3 h, then transplanted heterotopically using microvascular anastomoses. Intestinal graft segments were obtained after 20 min, 6 h, 12 h, and 24 h after reperfusion. Histology studies (goblet cell count, morphometry), immunofluorescence, and western blot for several tight junction proteins, apoptosis, and inflammation-related proteins were performed. Results: Cold storage led to extensive epithelial detachment, whereas reperfusion resulted in extensive villus loss (about 60% of the initial length), and goblet cell numbers were drastically reduced. Over the first 24 h, gradual morphologic and molecular recovery was noted, although several molecular alterations persisted (increased apoptosis and inflammation, altered expression of several tight junctions). Conclusions: The current data suggest that a near-complete morphologic recovery from a moderate mucosal injury occurs within the first 24 h after intestinal transplantation. However, several molecular alterations persist and need to be considered when designing intestinal transplant experiments and choosing sampling and endpoints. [ABSTRACT FROM AUTHOR]