Preserving the mucosal barrier during small bowel storage.

BACKGROUND: A major obstacle to successful small bowel transplantation is that of bacterial infection. The aim of this study was to preserve the small bowel mucosal barrier by using oxygenated luminal perfusion with a proven amino acid (AA)-based solution. METHODS: Rat small bowel (n=4) was flushed vascularly with modified University of Wisconsin solution and flushed luminally as follows: group 1, none (control); group 2, AA solution; group 3, 1-hr perfusion then storage with AA; group 4, continuous perfusion with AA. Energetics, malondialdehyde (MDA), glutathione (reduced), and histology were assessed over 24 hr at 4 degrees C. RESULTS: Within 4 hr, adenosine triphosphate (ATP) dropped by 25% to 65% in all groups except for group 4, which remained unchanged from fresh tissue values throughout 12 hr. After 12 hr, ATP in groups 1 through 3 had dropped to 0.5 to 0.9 micromol/g, compared with 1.5 micromol/g for group 4. Even after 24 hr, group 4 levels were more than twofold greater than groups 1 through 3. MDA increased transiently in tissues subjected to simple flush (no perfusion), whereas levels in perfused tissues remained elevated throughout the 24-hr period. Glutathione in group 1 dropped by greater than 50% from fresh tissue values but increased over 24 hr in groups 2 and 3 by 50% to 55%. Overall, histologic injury was markedly less in groups 2 through 4; however, after 24 hr, the lowest injury was observed in group 3 (median, grade 2) compared with groups 1 and 4 (grades 7 and 4). CONCLUSIONS: Our data indicate that perfusion clearly improves tissue energetics. However, mucosal integrity is markedly superior, with only a brief 1-hr period of perfusion; oxidative and mechanical stress are the factors likely responsible for injury resulting from continuous perfusion.

A novel technique of hypothermic luminal perfusion for small bowel preservation.

BACKGROUND: This study improved small bowel preservation using University of Wisconsin (UW) solution in conjunction with hypothermic luminal perfusion. METHODS: Small bowels from Sprague-Dawley rats (n=4) were flushed vascularly with modified UW solution and flushed luminally: group 1, none (clinical control); group 2, UW solution; group 3, 1-hr oxygenated perfusion then static storage with UW; and group 4, 24-hr continuous oxygenated perfusion with UW. Energetics, lipid peroxidation, and histology were assessed during 24 hr at 4 degrees C. RESULTS: After 12 hr, adenosine triphosphate ranged from 0.5 to 0.8 micromol/g in groups 1 to 3 compared with 1.5 micromol/g in group 4. Even after 24 hr, levels in group 4 were more than twofold greater than levels in groups 1 to 3. Energy charge values ([adenosine triphosphate+adenosine diphosphate/2]/total adenylates) decreased from fresh tissue values of 0.69 in all groups except group 4 throughout 24-hr perfusion. Malondialdehyde (MDA; a product of lipid peroxidation) doubled within 4 hr in group 1 and remained high throughout storage. In groups 3 and 4, MDA levels increased as the time of perfusion increased; group 2 showed no elevated MDA levels at any time. After 12 hr, histologic integrity was superior in groups 3 and 4; however after 24 hr, the best Park's grade was observed in group 3 (median grade 4) compared with groups 1 (grade 7) and 4 (grade 6). CONCLUSIONS: Our data indicate that perfusion clearly improves tissue energetics; however, mucosal integrity is superior with only a brief 1-hr period of luminal perfusion, despite limited improvements in energetics.