Surgeons could significantly reduce the rejection rate for transplanted organs following the development of a sensor system that monitors the deteriorationof organs while they are in transit.
At present donated organs are packed in liquid and transported in units based on a basic cool-box design. When they reach the hospital, they are assessed visually by surgeons who use their expertise and experience to determine whether they are still suitable for use. If the tissues have begun to break down, the organ may be rejected by its new host.
If a kidney fails recipients can go back on dialysis. When a liver is rejected patients have 72 hours to live if they do not receive a second organ. Heart patients die because there is no other means of keeping them alive.
Now researchers at the University of Ulster have developed flexible polymer-based nanosensors that are inserted into the organs to monitor deterioration after they are removed from the donor’s body. The microelectrodes detect the electrical and chemical characteristics of the organ’s cell tissue and can assess when it begins to deteriorate.
‘Worldwide transplants are limited by the availability of donor organs, so advances in procedures should lead to better success rates,’ says Dr Eric McAdams of Ulster University.
‘One of these advances could be improvements in information on graft viability. This would lead to better care and use of organ supplies and the use of good organs that might be mistakenly rejected. If the organs become unusable the sensor readouts offer clues as to why and what can be done to prevent the same thing happening in the future.’
‘Such a system would be very valuable to us,’ said Sandra Latimer, transplant co-ordinator at the Freeman Hospital in Newcastle. ‘While all 35 of our liver transplants in the past year were a success, there is always the risk that the organ may fail.’
Initially the Ulster team concentrated on producing silicon- based micro-probes to monitor tissue pH, temperature, potassium, sodium and calcium and the level of electrical impedance. However, the material proved too brittle, and the probes tended to break as they were removed.
Instead, the team developed a flexible probe by coating a polyimide substrate with gold. These are then coated with substances including diamond-like carbon or iridium oxide, depending on their intended use. The finished probes are mounted on connectors and encapsulated in biocompatible materials before insertion.
The sensors’ development forms part of the pan-European ESPRIT programme, launched six years ago to research ways of improving transportation methods for donor organs.
Data collected will allow scientists to determine the optimum temperature and the best liquids for transportation of individual organs.
The technology is about to undergo clinical trials to determine the best method for implanting the sensors.