Targeted immunotherapy with sphingosine-1-phosphate improves myocardial contractility and mitochondrial function in a novel murine ex vivo perfusion and transplantation model.

Abstract

To develop a reproducible ex vivo heart perfusion (EVHP) and murine heart transplantation model and to evaluate the efficacy of hypothermic, acellular ex vivo perfusion with sphingosine-1-phosphate (S1P) as a strategy to mitigate transplantation-associated ischemia-reperfusion injury (IRI). Donor hearts from wild-type mice were stratified by preservation technique. Group 1 hearts (n = 4) served as nontransplanted controls. Group 2 hearts (n = 10) underwent 90 minutes of cold static preservation (CSP) following cardioplegic arrest in donor mice. Group 3 to 5 hearts (n = 10/group) underwent EVHP with hypothermic acellular solution (Krebs-Henseleit buffer [KH]) alone (group 3), with KH plus S1P (FTY-720) (group 4), or with KH plus S1P plus S1P receptor subtype 2 antagonist (JTE-013) (group 5). Group 2 to 5 hearts were then transplanted into recipient mice with 120 minutes of reperfusion. Hearts were evaluated for function by echocardiography, for histopathologic injury by neutrophil infiltration, and for mitochondrial bioenergetics by Seahorse bioanalysis. Functional assessment demonstrated comparable post-transplantation allograft function as defined by fractional shortening (FS) and fractional area change (FAC) for CSP and KH-only EVHP mice (P > .05). EVHP with S1P improved post-transplantation function by both FS and FAC (P < .05). Coadministration of S1P with S1PR2 antagonist abrogated the functional improvement of S1P alone (P < .05). EVHP with S1P also reduced injury severity scores based on neutrophil infiltration (P < .05). Finally, EVHP with S1P transplanted hearts demonstrated improved mitochondrial function compared to hearts transplanted after standard CSP (P < .05). Donor hearts perfused with hypothermic acellular perfusate and S1P demonstrated improved post-transplantation heart function, decreased histologic injury, and increased mitochondrial performance compared to hearts preserved with cold-static CSP, representing a potential strategy to mitigate IRI occurring in heart transplantation.