BD and IRI impair cell viability of pancreatic isografts, which is ameliorated by BH4 treatment of the donor (A) Representative pictures of nontransplanted organs derived from naïve controls (I); sham‐treated animals (II); BD donors (III), BD donors treated with BH4 (IV). Grafts from non‐BD donors showed high cell viability after transplantation (V), similar to sham‐treated donors (VI). Transplantation of pancreata from BD donors into syngeneic recipients resulted in markedly reduced cell viability (VII), whereas amelioration of cell viability was observed in the treatment group (VIII). Representative pictures are shown for n = 5 animals/group. (B) The percentage of viable cells in biopsies taken after organ procurement or 2 h after reperfusion is shown. Data are presented as mean values of n = 5 animals/group ± SEM. Statistically significant differences were tested with one‐way ANOVA and the Tukey posttest; *p < 0.05, **p < 0.01. ANOVA, analysis of variance; BD, brain dead; BH4, tetrahydrobiopterin; IRI, ischemia reperfusion injury; SEM, standard error of the mean; Tx, transplantation.