Purpose: A greater interest in machine perfusion strategies for all solid organs has led to a substantial increase in the allocation and utilisation of human organs for research in the UK. Many research teams are employing ex vivo machine perfusion models in ischaemia-reperfusion studies. However, current 'reperfusion' models largely constitute the use of anti-coagulated packed red cells or whole blood through a centrifugal pump. The use of anti-coagulated blood does not allow for the study of coagulation and Complement, both important aspects of clinical reperfusion injury.

Methods: We designed an ex vivo reperfusion circuit based on commercially available cardiopulmonary bypass technology (HL20 – Maquet, Getinge Group). The heart-lung base allows creation of 'pulsatile' flow through the centrifugal pump, thereby closer mimicking clinical reperfusion. The system allows the operator to set a defined flow rate, therefore making it possible to reverse the anti-coagulant effects of citrate with a titrated calcium infusion pre-organ inflow and re-citrification of the organ outflow to prevent clotting of the circuit. Research grade, whole blood from National Health Service Blood & Transplant (NHSBT), was used in ex-vivo simulation of reperfusion in human kidneys (n=5) declined for transplantation, (consented and allocated for research by NHSBT, U.K). Blood gas measurements from the arterial inflow and venous outflow were analysed using a point of care device (i-STAT Handheld Blood Analyzer, Abbott Point of Care).

Results: Human kidneys were successfully perfused in this ex-vivo reperfusion circuit for up to two hours. Ionised calcium measurements were maintained at 0.9-1.0mmol/L immediately pre-arterial inflow and <0.35 mmol/L post-venous outflow by titration of calcium chloride and citrate infusions respectively. No circuits clotted using these parameters and continuous flow to the organ was maintained.

Discussion: This ex vivo organ reperfusion model represents a useful tool for the examination of reperfusion injury, particularly in respect to coagulation and complement activation following reperfusion. Although kidney reperfusion was examined in this model, the circuit set-up may also be developed and applied to other solid organs.

CITATION INFORMATION: Sandhu B, Bishop H, Loja D, Galloway-Phillips N, Crawley J, Pusey C, Papalois V. Human Organs Allocated for Research – Maximising Use of a Precious Resource Using a New Ex Vivo Model of Reperfusion Injury. Am J Transplant. 2017;17 (suppl 3).

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