PROTECTION OF CANINE PANCREATIC MICROVASCULAR ENDOTHELIUM AGAINST COLD ISCHEMIC INJURY DURING PRESERVATION BY THE TWO-LAYER METHOD

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Abstract
Ischemic injury of the microvascular endothelium during cold preservation causes a disturbance of vascular microcirculation after reperfusion and results in graft failure. Recently we have shown that oxygenation of the canine pancreas during preservation by the two-layer method extends the period of preserved pancreatic viability. The aim of this study was to clarify the role of the oxygenation of the pancreas graft by the two-layer method in the viability of the microvascular endothelium during preservation. After preservation of the canine pancreas by simple cold storage in Euro-Collins solution (EC) (group 1) or by the two-layer method using EC (group 2) for 48 hr, the viability of vascular endothelial cells was judged from nuclear trypan blue uptake. Pancreatic tissue perfusions were measured with a hydrogen gas clearance technique, and graft survival rates were examined after autotransplantation. In the control group, the grafts were autotransplanted without preservation (group 3). Graft survival rates were 0 of 5 (0%), 5 of 5 (100%), and 5 of 5 (100%) in groups 1, 2, and 3, respectively. The percentage of trypan blue-positive vascular endothelium in group 1 was significantly higher compared with group 3 (control) (26.4±1.7 vs. 7.4±4.3%, P <0.01). The two-layer method (group 2) decreased trypan blue uptake (11.3±3.7 vs. 26.4±1.7%, P <0.01). Pancreatic tissue perfusions after 2 hr of reperfusion were in inverse proportion to trypan blue uptake. Namely, pancreatic tissue perfusions in group 1 were significantly lower than group 3 (control) (45.6±12.8 vs. 64.5±20.6 ml/min/100 g, P <0.01). The two-layer method (group 2) improved pancreatic tissue perfusions (68.8±8.6 vs. 45.6±12.8 ml/min/100 g, P <0.01). We conclude that oxygenation of the pancreas during preservation by the two-layer method protects the microvascular endothelium from cold ischemic injury. Consequently, pancreatic microcirculation can be maintained after reperfusion, thus extending the period of preserved pancreatic viability.