Tetrahydrobiopterin Saves Pancreatic Isografts From Brain Death Exacerbated Ischemia Reperfusion Injury.: Abstract# C1642

Background: Brain death (BD) has been shown to immunologically prime grafts in part by aggravating ischemia reperfusion injury (IRI). Herein we assessed the effects of BD on IRI in an experimental setting furthermore the therapeutic potential of tetrahydrobiopterin (BH4), an essential NOS-cofactor was tested. Methods and Materials: Pancreas transplantation was performed using C57BL/6-mice. Animals underwent BD induction and were followed for 3h. Experimental groups included: non-treated BD-donors, BD-donors treated with 50mg/kg BH4, ventilated non-treated donors and living donors. Following 2 hours of reperfusion, microcirculation (functional capillary density, FCD; capillary diameter, CD) and cell viability was assessed by intravital fluorescence microscopy. Parenchymal graft damage was assessed by histology, ROS were quantified by immunohistochemistry against nitrotyrosin and mRNA expression of inflammatory candidate markers was measured by real-time RT-PCR. Results: Compared with controls, BD exacerbated IRI reflected by significantly reduced FCD and CD values (p<0.05). Moreover BD induced IL-1ß, TNFa, IL-6 and ICAM-1 mRNA expression (p<0.05). In contrast treated grafts displayed significantly higher FCD and CD values (p<0.05). BD had devastating impact on cell viability whereas treatment resulted in significantly higher numbers of viable cells after reperfusion (p<0.01). Parenchymal damage in grafts from BD-donors was significantly more pronounced when compared to controls (p<0.05). Treatment resulted in significantly better histology (p<0.05). Nitrotyrosin immunostaining showed significantly higher score values in grafts from BD donors when compared to BH4 treated pancreata (p<0.05). Conclusion: Our data gain new insights into the impact of BD on pancreatic grafts. Donor pre-treatment with BH4 offers a novel option for preventing BD exacerbated IRI.