SEVENTY-TWO HOURS HYPOTHERMIC INTESTINAL PRESERVATION STUDY USING A NEW PERFLUOROCARBON EMULSION

A new method to measure intestinal secretion using fluorescein isothiocyanate-inulin in small bowel of rats

BACKGROUND

Small intestine ischemia can be seen in various conditions such as intestinal transplantation. To further understand the pathologic disruption in ischemia-reperfusion injury, we have developed a method to measure fluid changes in the intestinal lumen of rats.

METHODS

Two 10-cm rat intestine segments were procured, connected to the terminal apertures of a perfusion device, and continuously infused with 3 mL of HEPES solution (control solution) containing 50 μM of fluorescein isothiocyanate (FITC)-inulin. The perfusion device consists of concentric chambers that contain the perfused bowel segments, which are maintained at 37°C via H₂O bath. The individual chamber has four apertures as follows: two fill and/or drain the surrounding HEPES solution on the blood side of the tissue. The others provide flow of HEPES solution containing FITC-inulin through the lumens. The experimental intestine was infused with the same solution with 100 μM of Forskolin. A pump continuously circulated solutions at 6 mL/min. Samples were collected at 15-min intervals until 150 min and were measured by the nanoflourospectrometer.

RESULTS

A mean of 6-μM decrease in the FITC-inulin concentration in the Forskolin-treated experimental intestine was observed in comparison with that in the control intestine. The FITC-inulin count dilution in the experimental intestine is a result of an increase of fluid secretion produced by the effect of Forskolin, with P values <0.0001.

CONCLUSIONS

We demonstrate that it is possible to measure luminal fluid changes over time using our new modified perfusion system along with FITC-inulin to allow real-time determinations of fluid and/or electrolyte movement along the small intestine.

The role of perfluorocarbon in organ preservation

Perfluorocarbons (PFCs) are inert solutions that have a high capacity for dissolving oxygen. There has been a continuing level of research into the delivery of oxygen during solid organ preservation with the use of PFCs. The one- and two-layer methods have been used as static storage techniques, proving particularly successful for pancreas preservation. They can also be formulated as an emulsion for continual perfusion or as a simple flush solution. The success of PFCs in organ preservation seems to be somewhat organ and species dependant, and further experimental evidence is needed to establish their application.

Molecular markers in stored kidneys using perfluorocarbon-based preservation solution: preliminary results

BACKGROUND

Delayed graft function (DGF) is a problem in kidney transplantation and cold ischemia has been identified as a risk factor. Perfluorocarbons (PFC) have an enhanced ability to dissolve and release oxygen. We evaluated histologically and a number of molecular changes induced by ischemia in stored kidneys with University of Wisconsin (UW) and PFC-based preservation solutions (PFC-UW).

MATERIALS AND METHODS

ACI rats were used as kidney donors. UW (control group) or PFC-UW (study group) preservation solutions were used for kidney perfusion. All kidneys were stored at 4 degrees C for 12, 24, and 36 hours. After this time, intragraft histologic evaluation as well as mRNA HO-1 and iNOS levels were also analyzed.

RESULTS

In the kidneys stored at 24 hours, mRNA HO-1 levels were elevated in the study group when compared with the control and mRNA iNOS was decreased.

CONCLUSION

We observed overexpression of HO-1 and underexpression of iNOS in the kidney tissue stored with PFC-UW solution at 24 hours. These preliminary data suggest that increasing oxygen delivery by PFC added to the perfusion solution triggers cytoprotective mechanism in kidney transplantation.

Luminal contact with University of Wisconsin solution improves human small bowel preservation

AIM

Under clinical conditions small bowel mucosa is stored without any contact between the mucosa and the preservation solution. We evaluated the impact of luminal contact with University of Wisconsin solution (UW) on the structural quality of small bowel preservation.

METHODS

Segments of ileum harvested from stable multi-organ donors were flushed with UW. For each donor, ileal segments were placed in UW without any contact between the mucosa and the preservation solution (group A), as is practiced in clinical conditions. Adjacent segments were cut on their antimesenteric side and placed in UW so that their mucosa was widely in contact with the solution (group B). The grafts preserved in ice were removed from the preservation fluid at different times (0, 3, 6, or 12 hours). Tissues were studied by optical microscopy after H&E staining of formalin-fixed, paraffin-embedded specimens. A median histologic score was calculated after examination of three random slides for each ileal segment per time point. Comparisons were performed between tissues of groups A and B from the same donor.

RESULTS

Control (0h) specimens showed normal histology. As early as 3 hours of preservation, group A tissues showed detachment of the villar epithelium. At 6 and 12 hours of preservation in this group further tissue alteration were obvious with complete epithelial detachment from the basal membrane of the villi. The histologic score of the segments preserved by luminal contact with UW was always significantly higher than the controls from the same donor.

CONCLUSION

Luminal contact between the mucosa of intestinal grafts and UW improves the quality of human small bowel preservation.

A new model for human intestinal preservation: comparison of University of Wisconsin and Celsior preservation solutions

AIM

We compared University of Wisconsin (UW) and Celsior preservation solutions using a new model of human intestinal preservation that mimics the clinical conditions of small bowel procurement.

METHODS

Intestinal grafts were harvested from four multiorgan donors. After classic warm dissection for organ procurement, an ileal segment of 50 cm was immediately flushed with Celsior. After the perfusion of the abdominal organs with UW, a second segment of adjacent ileum was harvested. The two intestinal grafts were then divided into segments by stapling, before immersion into the corresponding preservation solution (Celsior or UW) for 0-, 6-, 12-, or 24-hour incubation at 4 degrees C. A histological score was graded after blinded examination of three random specimens within each ileal graft for each duration of preservation.

RESULTS

Control specimens showed normal histology. After 6 hours of preservation, most villi showed complete epithelial detachment although the crypts appeared intact. After 12 hours of preservation, a larger proportion of the villi showed extensive epithelial sloughing. After 24 hours, the damage involved the entire mucosa with the crypt epithelium largely detached from the basal membrane. No statistical difference in histological score was observed between the two preservation solutions.

CONCLUSION

This study showed severe histological alterations of graft mucosa after short periods of preservation by UW or Celsior solutions. This model may be useful to evaluate improvements in the quality of preservation of human intestinal transplants.