AUTHOR=Critchley William R. , Stone John P. , Liao Qiuming , Qin Guangqi , Risnes Ivar , Trafford Andrew , Scott Helge , Sjöberg Trygve , Steen Stig , Fildes James E. 

TITLE=Non-ischemic Heart Preservation via Hypothermic Cardioplegic Perfusion Induces Immunodepletion of Donor Hearts Resulting in Diminished Graft Infiltration Following Transplantation

JOURNAL=Frontiers in Immunology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2020.01621

DOI=10.3389/fimmu.2020.01621

ISSN=1664-3224

ABSTRACT=<p><bold>Introduction:</bold> Many donor organs contain significant leukocyte reservoirs which upon transplantation activate recipient leukocytes to initiate acute rejection. We aimed to assess whether non-ischemic heart preservation via <italic>ex vivo</italic> perfusion promotes immunodepletion and alters the inflammatory status of the donor organ prior to transplantation.</p><p><bold>Methods:</bold> Isolated porcine hearts underwent <italic>ex vivo</italic> hypothermic, cardioplegic perfusion for 8 h. Leukocyte populations were quantified in left ventricle samples by flow cytometry. Cell-free DNA, cytokines, and chemokines were quantified in the perfusate. Tissue integrity was profiled by targeted proteomics and a histological assessment was performed. Heterotopic transplants comparing <italic>ex vivo</italic> hypothermic preservation and static cold storage were utilized to assess graft infiltration as a solid clinical endpoint.</p><p><bold>Results:</bold><italic>Ex vivo</italic> perfusion significantly immunodepleted myocardial tissue. The perfusate displayed a selective, pro-inflammatory cytokine/chemokine pattern dominated by IFN-γ. The tissue molecular profile was improved following perfusion by diminished expression of nine pro-apoptotic and six ischemia-associated proteins. Histologically, no evidence of tissue damage was observed and cardiac troponin I was low throughout perfusion. Cell-free DNA was detected, the source of which may be necrotic/apoptotic leukocytes. Post-transplant graft infiltration was markedly reduced in terms of both leucocyte distribution and intensity of foci.</p><p><bold>Conclusions:</bold> These findings demonstrate that <italic>ex vivo</italic> perfusion significantly reduced donor heart immunogenicity via loss of resident leukocytes. Despite the pro-inflammatory cytokine pattern observed, a pro-survival and reduced ischemia-related profile was observed, indicating an improvement in graft viability by perfusion. Diminished graft infiltration was observed in perfused hearts compared with those preserved by static cold storage following 48 h of transplantation.</p>