Biliverdin supplementation in perfusate and preservation solution attenuates ischemia-reperfusion injury in a rat donation-after-circulatory-death heart transplantation model

BACKGROUND: Heart transplantation faces a persistent donor shortage; therefore, hearts from donation after circulatory death have become a feasible option despite unavoidable warm ischemia and subsequent ischemia-reperfusion injury. Biliverdin, an endogenous bile pigment with strong antioxidant and anti-inflammatory properties, has shown protective effects against ischemia-reperfusion injury in several organ transplantation models. Whether biliverdin attenuates warm ischemic injury in donation after circulatory death heart transplantation remains unclear. This study evaluated biliverdin supplementation in the perfusate and preservation solution in a rat donation after circulatory death model. METHODS: Circulatory death was induced under deep anesthesia, and warm ischemia was maintained for 18 minutes, including the mandatory 5-minute stand-off period. Donor hearts were then flushed and subsequently cold-stored in the same biliverdin-supplemented extracellular-type trehalose-containing Kyoto solution, whereas control grafts received extracellular-type trehalose-containing Kyoto without biliverdin at both stages before heterotopic transplantation. Grafts were assessed at 3 and 24 hours after reperfusion (n = 6 per group). Evaluations included early graft recovery, myocardial injury markers, histological and ultrastructural changes, and inflammatory and stress-response gene expression. RESULTS: Biliverdin significantly improved early graft recovery, shortening reanimation time and increasing left ventricular fractional shortening at 24 hours. Serum troponin I levels were lower in biliverdin-treated grafts. Biliverdin also reduced histological injury and inflammatory cell infiltration. Ultrastructural analysis showed preserved mitochondrial architecture and ultrastructural integrity. Early proinflammatory gene expression was suppressed. CONCLUSION: Biliverdin supplementation in the perfusate and preservation solution attenuates ischemia-reperfusion injury in the experimental rat donation after circulatory death heart transplantation model. These findings provide proof of concept for further mechanistic and translational evaluation of biliverdin for myocardial protection in donation after circulatory death.