The histologic and molecular alterations during the cold storage of the ascending human colon

Inclusion of a colon segment in visceral grafts is increasing as this may improve water and electrolyte absorption and ultimately improve recipients' renal function. In contrast with the vast knowledge on the ischemia/reperfusion injury in the small bowel, similar data on the colon is almost inexistent. Using light microscopy, immunofluorescence and Western blot, we assessed several histological and molecular changes following the cold storage (CS) of the ascending colon of 18 human brain-dead organ donors for up to 24 h. CS induced progressive yet limited epithelial detachment and goblet cell depletion. Tight junction proteins claudin-1, claudin-3, claudin-4 and occludin were well preserved during the first 14 h of cold storage but its tissue expression decreased following 24 h of CS as evidenced by Western blot and immunofluorescence. ZO-1 expression remained unchanged throughout the 24 h of CS and showed a strong and continuous immunostaining along the entire epithelial lining. Expression of Na+/H+ exchanger (NHE)-1 and 2 remained unaffected by CS. Enterocyte apoptosis increased significantly after 14 h of CS. The current data indicate that colonic mucosa can withstand at least 14 h of cold ischemia without significant histological or molecular changes and implies that the small bowel remains the most vulnerable part of a prospective visceral allograft.