'Normothermic Machine Perfusion' for Organ Preservation

Featured on the Economist and the BBC

MetraA method for organ storage and transport devised by the Department’s Professor Constantin Coussios (Director of the Institute of Biomedical Engineering) and transplant surgeon Professor Peter Friend could result in major improvements to organ transplantation and was featured recently in the Economist. With liver disease now one of the UK’s most pressing health issues (deaths have soared by 40% in the last decade) and demand for transplants far exceeding the availability of usable donated livers, surgeons are keen to find ways to increase the transplant rate and help more people on their surgical waiting lists.

The ground-breaking method of preserving functioning organs at body temperature using the metra® machine was first used in a human liver transport in 2013, following the founding of the Organox spinout company in 2008. The metra® works by keeping the stored organ supplied with the correct amount of blood – a quantity which has to be regulated minute by minute. Since 2013 the metra® has since been used with over 250 transplant patients in six countries across two continents, demonstrating multiple benefits over the conventional method of cold storage.

However despite the desperate need for transplants, each year around 400 donor livers are judged unfit for use, leaving patients on the transplant waiting list. Livers may be deemed unsuitable due to the age of the donor, damage due to disease or diet, or in cases where they have degraded after been stored outside the body for too long, or when death has occurred away from a hospital. Researchers and clinicians hope the metra® could greatly increase the number of livers that are available for transplant by restoring otherwise unusable organs to a healthy functioning state.

A clinical trial at Queen Elizabeth Hospital in Birmingham used the technology in real-life surgery cases, testing its ability to recondition such livers to a point at which they meet the strict criteria for transplant1. In the trial, which was led by researchers at the hospital and University of Birmingham in collaboration with OrganOx Ltd and the University of Oxford, livers delivered to the hospital for transplants were attached to the metra® to undergo a process called normothermic organ perfusion. The process mimics conditions in the human body, providing blood, oxygen and nutrients at the body’s normal temperature. Over the course of four hours’ perfusion, readouts on liver performance such as blood flow, bile production and acidity indicate to the transplant team whether the organ is functioning well enough for transplant, enabling them to make an on-the-spot decision on whether to go ahead with surgery.

These clinical trials are high risk, but offer the possibility of better treatment in the future. Dr Coussios hopes that reducing the rate of organ rejection by transplant surgeons could, by itself, double the number which can be used in Britain. Hilary Fanning, Director of Research Development & Innovation at University Hospitals Birmingham NHS Foundation Trust, believes that clinical trials such as these, for which they recruit over 6,500 patients every year, could change the way in which future care is given: “Today’s research is tomorrow’s standard of care”.

For now, 25 of the OrganOx metras are now in use across the NHS, and Professor Constantin hopes to extend the concept to other vital transport organs such as kidneys: “Kidney dialysis is very expensive and it is a tough and restricting regime”, he says. “A transplant operation will free the patient from dialysis for ten years. If OrganOx can enable more kidney transplants to happen successfully, then we can make a real contribution to improving patients’ quality of life whilst also reducing healthcare costs for the NHS.”

Recent research also suggests that the current 24-hour limit on storage of organs in the metra® could safely be raised to three days or possibly longer, effectively increasing the number of transplant organs that hospitals with limited operating theatres can accept, store and use for surgery. Metras could also make it easier to perform the tricky operation of splitting livers in two, which is sometimes done to create a child-sized organ while still leaving enough over to transplant into an adult.

Recent research also suggests that the current 24-hour limit on storage of organs in the metra® could safely be raised to three days or possibly longer, effectively increasing the number of transplant organs that hospitals with limited operating theatres can accept, store and use for surgery. Metras could also make it easier to perform the tricky operation of splitting livers in two, which is sometimes done to create a child-sized organ while still leaving enough over to transplant into an adult.

Thanks to the ground-breaking developments made possible by UK research, and the dedication of surgeons and other clinicians, transplantation practice is changing. Pioneering machines like the Organox metra® may well be the ‘gold standard’ of transplant surgery in 10 years’ time.

The surgical trial is featured in recent BBC programme Surgeons: At the Edge of Life

 

1The trial, funded by the Wellcome Trust, started early November 2016 and ended late 2017

Published on: 29 January 2018