A comparative study of long-term heart preservation using 12-h continuous coronary perfusion versus 1-h coronary perfusion following 11-h simple immersion

Subzero 12-hour Nonfreezing Cryopreservation of Porcine Heart in a Variable Magnetic Field

BACKGROUND

A novel subzero nonfreezing heart preservation method has been developed. It uses a refrigerating device that generates a variable magnetic field, allowing the whole organ to be cooled simultaneously to a supercooled state without the use of cryoprotectant. As a fundamental experiment for heart preservation, we verified whether this novel method is able to suppress anaerobic metabolism and reduce damage in the hearts of large animals.

METHODS

Twelve porcine hearts were collected and preserved for 12 hours using a simple immersion method. The hearts were divided into 2 groups: 6 underwent nonfreezing preservation at -3°C in a variable magnetic field (subzero group), and 6 underwent conventional preservation at 4°C (conventional group). The quantity of anaerobic metabolism and the degree of ultrastructural change in the 2 groups were evaluated and compared.

RESULTS

The concentration of adenosine triphosphate in the myocardial tissue was significantly greater in the subzero group than in the conventional group (21.06±5.87 μmol/g vs 5.96±3.41 μmol/g; P < 0.05). The accumulated lactate concentration was significantly lower in the subzero group than in the conventional group (6.58±2.28 μmol/g vs 11.15±3.74 μmol/g; P < 0.05). The Flameng score, an index of ultrastructural changes to the mitochondria, was significantly lower in the subzero group than in the conventional group (1.28±0.40 vs 2.73±0.30; P < 0.05).

CONCLUSIONS

Subzero nonfreezing preservation using a variable magnetic field resulted in a remarkable suppression of anaerobic metabolism and myocardial protection in porcine hearts.

Comparative analysis of preservation method and intermittent perfusion volume on the expression of endothelial and inflammatory markers by coronal artery and myocardium in porcine donor hearts

Although continuous perfusion of donor hearts for preservation during transportation has been widely applied, intermittent perfusion has been suggested as an alternative. The aim of this study was to identify the optimal intermittent perfusion protocol by investigating the effects of perfusion volume on endothelial and inflammatory marker expression by the coronary artery. Donor porcine hearts were perfused with various volumes of Celsior solution supplemented with diazoxide (50, 100, 150, 200, and 250 ml) every 2 h for 30 min each for a 10 h period. The effects on cardiomyocytes and vascular endothelial cell morphology and marker expression were compared to the immersion control group. Whereas an incomplete endothelial cell layer with disorganized connective tissue was observed in the control and 50, 100, and 150 ml intermittent perfusion groups, transmission electron microscopic analysis revealed a complete endothelial cell layer in the intima with an organized subendothelium. A perfusion volume-dependent increase in eNOS expression that coincided with a decrease in ET-1, ICAM-1, vWF, and P-selectin expression was detected (all p < 0.01). Intermittent perfusion with 200 ml of Celsior solution every 2 h conferred protective effects simultaneously to the coronary arteries and myocardium on the porcine donor heart over a clinically relevant preservation period.

Subzero 24-hr nonfreezing rat heart preservation: a novel preservation method in a variable magnetic field

BACKGROUND

A new supercooling system using a variable magnetic field has been recently developed. Subzero nonfreezing preservation has been believed to be a beneficial method because of the lower metabolic rate. The purpose of this study was to evaluate the hemodynamic and metabolic effects of rat heart preservation in a variable magnetic field without cryoprotectants.

METHODS

Rat hearts were perfused ex vivo for 120 min after 24-hr preservation in two groups (n=6 each): (1) conventional storage group, in which the hearts were stored at 4°C, and (2) the subzero group, in which the hearts were preserved at -3°C in a variable magnetic field.

RESULTS

Reperfusion cardiac performance after preservation was significantly preserved in the subzero group compared with the conventional group with respect to heart rate, coronary flow, the peak positive dP/dt, and the peak negative dP/dt (P<0.05). Edema after reperfusion was significantly decreased (P<0.05), and the adenosine triphosphate level was higher in the subzero group (P<0.05).

CONCLUSIONS

The rat hearts preserved in a variable magnetic field at -3°C showed better hemodynamic and metabolic performance than those preserved using conventional storage at 4°C.

Organ Preservation: Current Concepts and New Strategies for the Next Decade

SUMMARY: Organ transplantation has developed over the past 50 years to reach the sophisticated and integrated clinical service of today through several advances in science. One of the most important of these has been the ability to apply organ preservation protocols to deliver donor organs of high quality, via a network of organ exchange to match the most suitable recipient patient to the best available organ, capable of rapid resumption of life-sustaining function in the recipient patient. This has only been possible by amassing a good understanding of the potential effects of hypoxic injury on donated organs, and how to prevent these by applying organ preservation. This review sets out the history of organ preservation, how applications of hypothermia have become central to the process, and what the current status is for the range of solid organs commonly transplanted. The science of organ preservation is constantly being updated with new knowledge and ideas, and the review also discusses what innovations are coming close to clinical reality to meet the growing demands for high quality organs in transplantation over the next few years.

Preserving and evaluating hearts with ex vivo machine perfusion: an avenue to improve early graft performance and expand the donor pool

Cardiac transplantation remains the first choice for the surgical treatment of end stage heart failure. An inadequate supply of donor grafts that meet existing criteria has limited the application of this therapy to suitable candidates and increased interest in extended criteria donors. Although cold storage (CS) is a time-tested method for the preservation of hearts during the ex vivo transport interval, its disadvantages are highlighted in hearts from the extended criteria donor. In contrast, transport of high-risk hearts using hypothermic machine perfusion (MP) provides continuous support of aerobic metabolism and ongoing washout of metabolic byproducts. Perhaps more importantly, monitoring the organ's response to this intervention provides insight into the viability of a heart initially deemed as extended criteria. Obviously, ex vivo MP introduces challenges, such as ensuring homogeneous tissue perfusion and avoiding myocardial edema. Though numerous groups have experimented with this technology, the best perfusate and perfusion parameters needed to achieve optimal results remain unclear. In the present review, we outline the benefits of ex vivo MP with particular attention to how the challenges can be addressed in order to achieve the most consistent results in a large animal model of the ideal heart donor. We provide evidence that MP can be used to resuscitate and evaluate hearts from animal and human extended criteria donors, including the non-heart beating donor, which we feel is the most compelling argument for why this technology is likely to impact the donor pool.