Ex Vivo Hypothermic Perfusion Enables 48-Hour Heart Preservation and Bench-Top Functional Recovery via Normothermic...

Ex vivo oxygenated perfusion systems are a promising approach to extend cardiac allograft preservation beyond the typical 4 to 6 hours limit allowed by static cold storage (SCS). Hypothermic oxygenated perfusion (HOPE) has been proven to safely preserve donor hearts, yet its underlying molecular mechanisms have not been extensively evaluated. The aim of the study is to characterize cardiomyocyte viability, transcriptomic and metabolomic responses, and functional recovery of porcine hearts preserved with HOPE for up to 48 hours, including evaluating their ability to regain sinus rhythm following bench-top normothermic reperfusion.

Seventeen Yorkshire pigs underwent donor cardiectomy. In the first arm, 10 hearts were preserved for up to 48 hours using either SCS (n=5) or HOPE (n=5). Endomyocardial biopsies were collected at 0, 12, 24, and 48 hours for histology, RNA sequencing, flow cytometry, and metabolomics. In the second arm, 6 HOPE-preserved hearts (3, 24, 48 hours) and 2 SCS-preserved heart (3 and 24 hours) underwent 2 hours of normothermic reperfusion to simulate transplantation and assess reanimation.

HOPE preserved cardiomyocyte viability and structural integrity for 48 hours, in contrast to SCS in both arms of the study. RNA sequencing and untargeted metabolomics revealed conserved energy-substrate profiles in HOPE and progressive ischemic metabolite accumulation in SCS. All HOPE hearts regained stable sinus rhythm.

HOPE enables 48 hours ex vivo heart preservation while maintaining cardiomyocyte integrity, normal gross and microscopic architecture, and rapid functional recovery on bench-top reperfusion in a preclinical model. These findings establish a foundation for redefining clinical preservation times and widening geographic donor access.