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

Abstract

Introduction: 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 ex vivo perfusion promotes immunodepletion and alters the inflammatory status of the donor organ prior to transplantation. Methods: Isolated porcine hearts underwent ex vivo 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 ex vivo hypothermic preservation and static cold storage were utilized to assess graft infiltration as a solid clinical endpoint. Results: Ex vivo 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. Conclusions: These findings demonstrate that ex vivo perfusion significantly reduced donor heart immunogenicity via loss of resident leukocytes. Despite the pro-inflammatory Critchley et al. Immunodepletion of the Donor Heart 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.

Acute rejection after liver transplantation with machine perfusion versus static cold storage: A systematic review and meta-analysis

“…Most immunosuppressive agents act at the T cell level [31] however, upstream pathways may also be targeted to reduce rejection. The link between oxygenated perfusion and immunomodulation has been shown in animal models for kidneys, [32] heart, [33] and liver, [34] providing oxygen during organ storage diminished the initial oxidative stress and DAMP molecule release, thus downregulating the entire immune activation cascade. Mitochondria have been shown to be an important therapeutic target to reduce acute rejection in other solid organs as well, such as hearts, [35] lungs, and kidneys.…”

Expanding Donor Heart Utilization Through Machine Perfusion Technologies

“…In addition to this work, Michel and Madsen [38] reported that a NIHP porcine model resulted in hearts with less depletion of ATP stores and improved preservation of mitochondrial structure. Critchley et al [39] echoed the physiological benefits of NIHP -in this study, six Swedish pigs underwent heart retrieval. Three organs were preserved with SCS for 2 h and the remainder were preserved for 8 h with NIHP.…”

Machine Perfusion for Human Heart Preservation: A Systematic Review

“…MP may reduce acute graft rejection. A porcine heart study showed that NIHP could significantly reduce donor heart immunogenicity via loss of resident leukocytes, reducing recipient T cell recruitment up to 48 h following transplantation in the absence of immunosuppression ( 47 ). No clinical study has addressed on this topic so far.…”