Evaluation of Persufflation and Cold Storage Preservation in Isolated Porcine Kidneys Using Novel Methods for Organ Quality Assessments

Abstract

Organ shortage is a persistent, widespread problem that deprives hundreds of thousands of people from a better quality of life. While the improvements in preservation solutions, immunosuppressants and surgical techniques have steadily increased successful outcomes, the scarcity in organs continue to worsen with transplant patients on the waiting list dying every day. In order to overcome this dilemma, organs from many donor types are being used with varying degrees of risk factors and damage. Currently, there are no systematic, universal ways of quantifying organ quality in a way that can predict graft function once it’s been transplanted. Although various preservation methods are being explored to extend the life of the organ, delayed graft function and complications after the transplant caused by ischemic damage during the procurement and preservation process has yet to be resolved. We had two overarching goals for these experiments. The first was the development of noninvasive quality assessment methods that can characterize organs prior to transplantation. The second was to test anterograde persufflation as a method for organ preservation. Persufflation is a technique that delivers humidified, gaseous oxygen directly into the vasculature to ensure even and thorough oxygenation of the whole organ. In previous studies, it has been shown to extend the preservation time, replenish energy levels and improve the function of the organ. For these experiments, whole organ oxygen consumption rate was used as a measure of tissue viability. Additionally, dynamic contrast enhanced magnetic resonance imaging was used as a tool to calculate glomerular filtration rate, the standard measure of renal function. In conjunction with these assessment techniques, immunohistochemistry, biomarkers and genomic analyses were employed to further elucidate the effects of persufflation on isolated organs. Renal allotransplants were attempted in a pre-clinical porcine model to determine the physiological relevance of persufflation. Overall, results from studies using isolated kidneys show higher oxygen consumption rate and higher GFR in the persufflated kidneys compared to the static cold storage kidneys, which were interpreted as increased metabolism and function. Higher levels of lactate that are indicative of anaerobic metabolism were measured in the cold storage kidneys. on the other hand, histological analyses revealed no significant differences between the two treatment groups in terms of morphological changes Microarray data show an upregulation of genes and pathways involved in renal reparative actions, stress response and immune response in the persufflated kidneys. These results likely reflect a more metabolically active organ that is responding to the ischemic insult. The pig renal allotransplant model shows regeneration in the renal tubules of the persufflated kidney, while the cold storage counterpart shows diffuse necrosis. While it is premature to make any assumptions about the in vivo effects of persufflation from the transplant model, it provides a foundation for subsequent large animal model pre-clinical studies.