Warm preflush with streptokinase improves microvascular procurement and tissue integrity in liver graft retrieval from non-heart-beating donors.

Abstract

Apart from the warm ischemic insult, integrity of liver grafts from non-heart-beating donors (NHBD) is additionally affected by microvascular alterations including erythrocyte aggregation and thrombus formation, which might hamper appropriate equilibration of the preservation solution to the grafts' microvasculature precluding cold preservation. Thus, the objective of our study was to characterize microvascular perfusion quality of University of Wisconsin (UW) solution during initial flushout of livers from NHBD rats, and to analyze the effects of an additional warm preflush with Ringer's lactated solution (RL) and with RL containing streptokinase (SK). Cardiocirculatory arrest was induced by phrenotomy. Subsequent to 30 min of warm ischemia, livers were perfused via an aortic catheter by gravity of 100 cm H2O either with 4 degrees C 100 ml UW solution (UW, n=7), or with 25 degrees C 30 ml RL preflush followed by 4 degrees C 100 ml UW solution (RL+UW, n=7), or with 25 degrees C 30 ml SK- (7500 IU) containing RL preflush and 4 degrees C 100 ml UW solution (SK/RL+UW, n=6). Liver microperfusion was quantified using in situ fluorescence epi-illumination microscopy. Liver microcirculation of sham-operated living animals (n=4) served as controls. Enzyme release after a 24-hr cold preservation period was used as an indicator of graft integrity. After 30 min of warm ischemia, microvascular perfusion of UW solution was found markedly altered when compared with that of sham-operated living controls, as indicated by a significant reduction (P<0.05) of acinar and sinusoidal perfusion. Preflush with RL (RL+UW) only slightly attenuated the acinar and sinusoidal perfusion deficits, whereas the addition of SK to RL (SK/RL+UW) resulted in a significant improvement of microvascular graft perfusion (P<0.05). Accordingly, the increased enzyme release observed in solely UW-flushed livers after 24 hr cold preseravtion was only slightly influenced by preflush with RL, but markedly attenuated (P<0.05) by pre-flush with RL containing SK. The additive fibrinolytic therapy using SK is effective to improve microvascular procurement of livers after warm ischemia and may thus represent a promising approach to attenuate parenchymal cell injury in liver graft retrieval from NHBD.