Chairmen, Ladies and Gentlemen

The trend in kidney transplantation has shifted over the last decade, in the presence of an ever expanding waiting list of patients, living donor transplant rates have begum to plateau and there has been a steady increase in Donation after cardiac death kidney transplants. The full potential of DCD kidney harvest as a resource is yet to be utilized and there are pitfalls….

At Leicester we have developed our own normothermic kidney perfusion technique. This is used in conjunction with hypothermia We have found that changing the way in which you preserve an organ by introducing a short period of normothermic perfusion after hypothermic preservation can improve the condition of an organ. In a laboratory study using porcine kidneys we subjected kidneys to 10 minutes of WI then either statically cold stored them for 18 hours or static cold storage for 16h followed by 2 hours of normothermic perfusion. In the NP kidneys ATP was replenished and protective mechanisms such as HSP 70, known to have a role in regeneration and repair are up-regulated compared to the CS kidneys.

The aim of this study was to introduce normothermic perfusion into clinical practice for kidneys from marginal donors to assess the safety and feasibility.

Normothermic perfusion can be carried out quite simply in clinical practice in the following way. A suitable kidney is identified and the recipient consented. Whilst the recipient is being anesthetised and the vessels exposed there is a window in which to carry out NP without prolonging the preservation period. The kidney is prepared in and the renal artery and vein cannulated. It then undergoes a period of normothermic perfusion, around 60 minutes. Once ready for transplantation it is flushed with cold preservation solution and then transplanted.

This is a systematic diagram of the NP system. It is based on paediatric cardiopulmonary by technology made by Medtronic. We used a red cell based solution, it is added to the venous reservoir then pumped through a centrifugal pump into a membrane oxygenator and heater where it is oxygenated and warmed. The perfusate then enters the arterial arm of the circuit and into the kidney via the renal artery. It is allow to drain out of the renal vein back into reservoir where it is continually re-circulated. The system provides a continuous blood flow to the kidney rather than a puslatile flow The kidney also produces urine. This is a short video of the system in action. The renal artery and caval tube are cannulated and the kidney placed in a sterile chamber. It is then attached to the system. Kidneys are perfused at a set arterial pressure of 60-65mmHg and constant temperature of around 35C. We use 1 unit of compatible red blood cells which was supplemented with a priming solution containing, a crystalloid solution, an anti-inflammatory agent and antibiotics. A nutrient solution containing multivitamins and insulin and also a vasodilator (Prostacyclin) and glucose are infused into the system. The perfusate and perfusion conditions are design to create an overall protective environment.

Allows pre-transplant functional assessment - viability testing Marginal kidneys tolerate cold ischaemia less well than standard criteria and LD kidneys

We have identified 17 suitable kidneys to undergo normothermic perfusion. 16 from ECD and 1 DCD. The average age was 56, 5 male, 12 female and death caused largely by and intracranial haemorrhage. The average age of the recipient was 58 years, 12 female and 5 male. All the recipients received a standard triple therapy immunosuppression protocol.

Kidneys underwent normothermic perfusion for an average of 65 minutes. The mean arterial pressure was 62mmHg. The renal blood flow increased throughout perfusion and all kidneys appeared well perfused. They produced urine although the amount was variable ranging from 30 to 450ml. The perfusion conditions were kept stable although there was a slight fall in the haematocrit level.

All kidneys were transplanted successfully. 3 of the kidneys had a period of warm ischaemia prior to retrieval, 13, 25 and 35 minutes. The cold ischaemic time was relatively short around 12 hours, anastomosis 27 minutes and the median hospital stay 7 days.

There were no indices of PNF. 16 out of 17 kidneys had immediate graft function. I patient had DGF and required 2 episodes of dialysis during the first week. 2 Patients had SGF defined as a less than 10% fall in serum creatinine on 3 consecutives days during the first week. 4 patients had acute rejection within the first 3 months. All were treated successfully. There were no adverse effects in any of the patients. Graft survival at 6 months was 100%. We have 2 patients out to 12 months all of which are doing extremely well.

This is the first reported application of Normothermic kidney perfusion in clinical practice. This series of 17 cases has demonstrated it to be a safe and feasible method of preservation. It restores aerobic metabolism and function. This early evidence suggest that it may improve early graft function. Furthermore, it has the potential to be developed into a devise in which to deliver therapies directly to the kidney or as a devise on which to assess the condition of the kidney prior to transplantation.

Improving Kidney Transplantation by ‘Pre-Conditioning’ Sarah A Hosgood & Michael L Nicholson University of Leicester, Transplant Group. UK

Renal Transplant Activity

Marginal Kidneys DCD/ECD High rates of delayed graft function and slow graft function Primary non function Increased incidences of acute rejection Prolonged hospital stay

Kidney Preservation ‘Maintain organ viability after donation until transplantation’ Hypothermia to suppress the metabolism Little development since the 1980’s Static cold storage Hypothermic machine perfusion

Pre-Conditioning ‘Normothermic Perfusion (Resuscitation)’ Restore renal function and metabolism Improve the condition of the kidney Reduce the injury after transplantation Improve early graft function

Infusion fluids Urine collection bag Temperature probe Organ chamber Venous reservoir Centrifugal pump Kidney Perfusion System Oxygenator

Normothermic Perfusion Pre-conditioning Hosgood SA et al Br J Surg 2008

Porcine Autotransplant Model Results Hosgood SA et al J Surg Res 2010

Pilot Study Determine the safety and feasibility of normothermic perfusion in marginal donor kidney transplantation

Pilot Clinical Study Marginal Kidneys Pilot study Safety and Efficacy

Clinical Application of Normothermic Perfusion

Flow probe Centrifugal Pump Pressure line Oxygenator/heater Infusion Pumps Urine collection Isolated Kidney Perfusion System Venous Reservoir

Perfusion System and Conditions • 1 unit cross-matched packed red cells + 500 ml crystalloid • Mean arterial pressure 65 mmHg • 34-37oC • TPN (no lipid); Dexamethasone; PGI2 • Antibiotics ‘Ideal perfusion’

Demographics Immunosuppression Basiliximab Tacrolimus Mycophenolate mofetil Prednisolone

Normothermic Perfusion Parameters

Results

Patient Outcome *Dialysis in the first 7 days †Creat fall < 10%/day  3days 0/19

ECD Kidneys: Leicester Series n = 30 n = 19 n = 30 n = 19

Summary & Conclusion This is the first reported application of normothermic kidney perfusion in clinical practice Normothermic perfusion ‘pre-conditioning’ Safe and feasible Restores aerobic metabolism ex-vivo May improve initial graft function

Acknowledgements

Future Development Normothermic ‘conditioning’ Optimise early graft function Increase marginal kidneys Stem cells Gene therapy