There are 107,653 people awaiting a kidney transplant in the US, while 16,420 await a liver transplant. Although the waiting lists are long, health care professionals face the difficult task of ensuring organ donations are suitable in order to maximize longevity and health of patients, as well as ensuring transplant procedures do not affect the quality of the organs. Three new studies investigate ways in which such processes can be improved.
The studies were recently published in the British Journal of Surgery.
A research team in the UK, led by Dr. Rajeev Desai of NHS Blood and Transplant, conducted the first study. They wanted to investigate the risk of cancer transmission from donor organs.
In the background information of their research, the authors note that the risk of such transmission is small, at 0.01-0.05%. However, some donor organs are refused for transplantation because the risk of cancer transmission to the recipient is deemed too high, meaning many recipients die before an alternative donor organ becomes available. But the research team says evidence to support such recommendations is "scanty."
The team analyzed transplants from 17,639 donors. Of these, 61 had cancer and were considered to have a "high" or "unacceptable" risk of transmitting cancer through their organs.
The team found there was no cancer transmission in 133 recipients who were transplanted with organs from these donors. On assessing the recipients 10 years after transplantation, the researchers found that, on average, they experienced an additional 7 years survival.
Dr. Desai says that based on these findings, it appears that the perceived risk of organ donors transmitting cancer to their recipients is likely to have been "overestimated," adding:
"Organ donors with a history of certain types of cancers, who are excluded from transplantation, in fact pose very little risk of cancer transmission to their recipients. These organs can be transplanted with very little risk to their recipients, resulting in significant improvement in the survival and health of the recipients."
Does age matter when it comes to organ donations?
In a second study, researchers led by Dr. Oliver Detry, of the University of Liège in Belgium, looked at whether transplanting livers from donors above the maximum age recommendation of 60 years affected recipient outcome.
In one study, researchers found that the age of the donor does not affect recipient outcome, as long as the organ is kept in cold storage for less than 6 hours.
The team focused on donations after circulatory death (DCD). This is when organs are used from donors whose heartbeat, circulation and breathing have stopped, rather than from donors whose brain functions have stopped.
Liver transplants were assessed from 70 DCD donors. Of these, 32 were from donors aged 55 years and younger, 20 were from donors aged between 56 and 69 years, while 18 were from donors aged 70 years and over.
On analyzing recipient survival 1 and 3 years after transplantation, the team found that survival rates were no different between age groups, as long as the cold ischemic time - the time between the chilling of the organ after blood supply has ceased and the warming of the organ through blood supply restoration - less than 6 hours.
"As the population of Western countries is aging, we will have to consider older donors even more often in the future," Dr. Detry comments.
Cold storage time 'could predict potential organ failures'
In another study, Thamara Perera of the Queen Elizabeth Hospital in the UK and colleagues assessed the importance of reducing cold ischemic time after circulatory death as a way of preserving the energy of organs for transplantation.
The team used microdialysis to reach their findings - a method in which researchers can look at the differences in energy between organs from brain death and DCD donors.
The researchers discovered that livers from DCD donors lost energy during cold storage. In addition, livers that failed after transplantation were those that lost a significant amount of energy.
Commenting on the results of the study, Perera says:
"The importance of these findings is the ability to predict possible organ failures and unwanted outcomes before performing the actual transplant. The study also questions the suitability of organ preservation techniques that are currently in place."
Earlier this year, Medical News Today reported on a study suggesting that donor lungs from heavy smokers are safe for transplantation and that current recommendations should be reviewed to reflect this.