Current Basic Research in Normothermic Machine Perfusion

Normothermic machine perfusion (NMP) is gradually being introduced into clinical transplantation to improve the quality of organs and increase utilisation. This review details current understanding of the underlying mechanistic effects of NMP in the heart, lung, liver, and kidney. It also considers recent advancements to extend the perfusion interval in these organs and the use of NMP to introduce novel therapeutic interventions, with a focus on organ modulation.

The re-establishment of circulation during NMP leads to the upregulation of inflammatory and immune mediators, similar to an ischaemia-reperfusion injury response. The level of injury is determined by the condition of the organ, but inflammation may also be exacerbated by the passenger leucocytes that emerge from the organ during perfusion. There is evidence that damaged organs can recover and that prolonged NMP may be advantageous. In the liver, successful 7-day NMP has been achieved. The delivery of therapeutic agents to an organ can aid repair and be used to modify the organ to reduce immunogenicity or change the structure of the blood group antigens to create a universal donor blood group organ.

The application of NMP in organ transplantation is a growing area of research and is increasingly being used in the clinic. In the future, NMP may offer the opportunity to change practice. If organs can be preserved for days on an NMP system, transplantation may become an elective rather than an emergency procedure. The ability to introduce therapies during NMP is an effective way to treat an organ and avoid the complexity of treating the recipient.