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Using an Isolated Working Rat Heart Model to Test Donor Heart Preservation Strategies

Optimization of donor heart preservation solutions has played a key role in reducing ischemia-reperfusion injury in donor hearts during organ retrieval, ...

Victor Chang Cardiac Research Institute

Orthotopic heart transplantation is the gold-standard long-term treatment for medically refractive end-stage heart failure. However, suitable cardiac donors are scarce. Although donation after circulatory death has been used for kidney, liver, and lung transplantation, it is not used for heart transplantation. We report a case series of heart transplantations from donors after circulatory death.

Adult heart transplantation with distant procurement and ex-vivo preservation of donor hearts after circulatory death: a case series.

Hearts from older donors are increasingly being referred for transplantation. However, these hearts are more susceptible to ischemia-reperfusion injury (IRI), reflected in higher rates of primary graft dysfunction. We assessed a strategy of pharmacologic conditioning, supplementing Celsior (Genzyme, Naarden, The Netherlands) preservation solution with glyceryl trinitrate (GTN; Hospira Australia Pty, Ltd, Mulgrave, VIC, Australia), erythropoietin (EPO; Eprex; Janssen-Cilag, North Ryde, NSW, Australia), and zoniporide (ZON; Pfizer, Inc., Groton, CT), to protect older hearts against IRI and improve graft function.

Improved heart function from older donors using pharmacologic conditioning strategies.

The ryanodine receptor antagonist dantrolene inhibits calcium release from the sarcoplasmic reticulum and reduces cardiac ischaemia-reperfusion injury (IRI) in global warm ischaemia models however the cardioprotective potential of dantrolene under hypothermic conditions is unknown. This study addresses whether the addition of dantrolene during cardioplegia and hypothermic storage of the donor heart can improve functional recovery and reduce IRI. Using an ex vivo isolated working heart model, Wistar rat (3 month and 12 month) hearts were perfused to acquire baseline haemodynamic measurements of aortic flow, coronary flow, cardiac output, pulse pressure and heart rate. Hearts were arrested and stored in Celsior preservation solution supplemented with 0.2-40 μM dantrolene for 6 hours at 4°C, then reperfused (15 min Langendorff, 30 min working mode). In 3-month hearts, supplementation with 1 μM dantrolene significantly improved aortic flow and cardiac output compared to unsupplemented controls however lactate dehydrogenase (LDH) release and contraction bands were comparable. In contrast, 40 μM dantrolene-supplementation yielded poor cardiac recovery, increased post-reperfusion LDH but reduced contraction bands. All 3-month hearts stored in dantrolene displayed significantly reduced cleaved-caspase 3 intensities compared to controls. Analysis of cardioprotective signalling pathways showed no changes in AMPKα however dantrolene increased STAT3 and ERK1/2 signaling in a manner unrelated to functional recovery and AKT activity was reduced in 1 μM dantrolene-stored hearts. In contrast to 3-month hearts, no significant improvements were observed in the functional recovery of 12-month hearts following prolonged storage in 1 μM dantrolene.

Functional recovery after dantrolene-supplementation of cold stored hearts using an ex vivo isolated working rat heart model.

Enhanced functional recovery of the heart donated after circulatory death determination with antemortem heparin.

The cardioprotective potential of the sodium-glucose cotransporter 2 inhibitor empagliflozin in donor heart preservation.

Hearts from older donors or procured via donation after circulatory death (DCD) can alleviate transplant waitlist; however, these hearts are particularly vulnerable to injury caused by warm ischemic times (WITs) inherent to DCD. This study investigates how the combination of increasing donor age and pharmacologic supplementation affects the ischemic tolerance and functional recovery of DCD hearts and how age impacts cardiac mitochondrial respiratory capacity and oxidative phosphorylation.

The Effect of Increasing Donor Age on Myocardial Ischemic Tolerance in a Rodent Model of Donation After Circulatory Death.

Heart transplantation from donation after circulatory death (DCD) donors has the potential to substantially increase overall heart transplant activity. The aim of this report is to review the first 8 y of our clinical heart transplant program at St Vincent's Hospital Sydney, to describe how our program has evolved and to report the impact that changes to our retrieval protocols have had on posttransplant outcomes. Since 2014, we have performed 74 DCD heart transplants from DCD donors utilizing a direct procurement protocol followed by normothermic machine perfusion. Changes to our retrieval protocol have resulted in a higher retrieval rate from DCD donors and fewer rejections of DCD hearts during normothermic machine perfusion. Compared with our previously reported early experience in the first 23 transplants, we have observed a significant reduction in the incidence of severe primary graft dysfunction from 35% (8/23) to 8% (4/51) in the subsequent 51 transplant recipients ( P < 0.01). The only withdrawal time interval significantly associated with severe primary graft dysfunction was the asystolic warm ischemic time: 15 (12-17) versus 13 (11-14) min ( P < 0.05). One- and 5-y survival of DCD heart transplant recipients was 94% and 88%, comparable to that of a contemporary cohort of donation after brain death recipients: 87 and 81% ( P -value was not significant). In conclusion, heart transplantation from DCD donors has become a major contributor to our overall transplant activity accounting for almost 30% of all transplants performed by our program in the last 2 y, with similar DCD and donation after brain death outcomes.

Heart Transplantation From DCD Donors in Australia: Lessons Learned From the First 74 Cases.

To highlight the current global experience with DCD heart transplantation and explore the evolution of, and compare preservation strategies; examine early clinical outcomes, and discuss the growing use of DCD donors as a new frontier in heart transplantation.

Donation After Circulatory Death: A New Frontier.

Primary graft failure (PGF) is a devastating complication that occurs in the immediate postoperative period following heart transplantation. It manifests as severe ventricular dysfunction of the donor graft and carries significant mortality and morbidity. In the last decade, advances in pharmacological treatment and mechanical circulatory support have improved the outlook for heart transplant recipients who develop this complication. Despite these advances in treatment, PGF is still the leading cause of death in the first 30 days after transplantation. In today's climate of significant organ shortages and growing waiting lists, transplant units worldwide have increasingly utilised "marginal donors" to try and bridge the gap between "supply and demand." One of the costs of this strategy has been an increased incidence of PGF. As the threat of PGF increases, the challenges of predicting and preventing its occurrence, as well as the identification of more effective treatment modalities, are vital areas of active research and development.

Primary graft failure after heart transplantation.

Donation after circulatory death (DCD) provides an alternative pathway to deceased organ transplantation. Although clinical DCD lung, liver, and kidney transplantation are well established, transplantation of hearts retrieved from DCD donors has reached clinical translation only recently. Progress has been limited by concern regarding the viability of DCD hearts. The aim of this study was to document the pathophysiological changes that occur in the heart and circulation during withdrawal of life (WLS) support.

Pathophysiological Trends During Withdrawal of Life Support: Implications for Organ Donation After Circulatory Death.

Storage of donor hearts in cardioplegic solutions supplemented with conditioning agents activating endogenous mitochondrial protective signaling enhanced their postreperfusion recovery. The present study investigates the role of timing and duration of cardiac exposure to cyclosporine A (CsA), another putative mitochondrial protectant, on cardiac functional recovery and potential mechanisms of CsA action in an isolated working rat heart model of donor heart retrieval and storage.

Aoife Doyle

Cardiac Physiology and Transplantation

Victor Chang Cardiac Research Institute

Using an Isolated Working Rat Heart Model to Test Donor Heart Preservation Strategies

Aoife Doyle

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Cardiac Physiology and Transplantation

Victor Chang Cardiac Research Institute

Using an Isolated Working Rat Heart Model to Test Donor Heart Preservation Strategies

Cardiac Physiology and Transplantation