Further evaluation of Somah: long-term preservation, temperature effect, and prevention of ischemia-reperfusion injury in rat hearts harvested after cardiocirculatory death

Abstract

Objective: To identify and evaluate the ideal temperature for long-term storage of hearts from donation after cardiocirculatory death, in the novel organ preservation solution Somah.

Methods: DCD hearts from Sprague-Dawley rats were harvested after 30 minutes of euthanasia, preserved in Somah at 4°C, 10°C, 21°C, or 37°C for 24 hours and then reperfused with blood:Somah (3:1) perfusate at 37°C for 30 minutes. Myocardial biopsies were taken during storage and before and after reperfusion to assess the structural and functional viability of tissue using multiphoton imaging, biochemistry, and immunofluorescence.

Results: Myocyte viability, determined by Live-Dead and esterase assays, was similar at 4°C, 10°C, and 21°C (193, 198 and 217 normalized fluorescence counts [NFC]) with a significant decrease at 37°C (131 NFC). Upon reperfusion, esterase activity was enhanced in DCD hearts stored in Somah at 21°C but noticeably decreased at all other temperatures. High-energy adenosine triphosphate/creatine phosphate (ATP/CP) syntheses and the expression of structural/contractile proteins was well preserved at 21°C, both after 24-hour storage and upon reperfusion. In contrast, hearts stored at all other temperatures demonstrated variable degenerative changes, loss of protein expression, and/or deranged ATP/CP synthesis after 24 hours of storage and/or upon reperfusion.

Conclusion: The robust maintenance of structural/functional integrity of cardiac tissue and the preservation of protein expression and cellular energy metabolism in DCD hearts after long-term preservation at subnormothermic temperature suggests that 21°C is ideal for long-term storage of DCD hearts in Somah solution.