A team of scientists has vastly extended the time window in which a liver to be transplanted can be kept waiting to reach a patient.
By modifying a protocol necessary to conserve the liver of rodents, the scientists observed results so promising that they were tested on a human liver to be transplanted.
A donor liver had an average "life" of 9 hours, the new method brings this time to 27 hours. A lot of extra time to organize the operation, to increase the transport radius of the organ, to prepare the recipient.
A great, great discovery.
The research is supported byUSA National Institute of Bioengineering (NIBIB) and by other bodies of the American National Institute of Health.
What happens to a liver to be transplanted
Like a glass that breaks when it gets too cold, cells often receive irreparable damage from the freezing process. The sensitivity of human cells involves the need to freeze a donor's liver below 4 ° C. This brings the useful time to a transplant to 9 hours, beyond which the damages of the cold become irreversible.
This is why it is often very difficult, and sometimes impossible, to get compatible organs to reach people waiting for a transplant.
“Delivering healthy organs in the time window is one of the most complex aspects of an organ transplant,” says Seila Selimovic, Ph.D, director of the NIBIB tissue engineering program. “Giving doctors and patients more time means saving many people waiting for a transplant.”
The first research
A study by Massachusetts General Hospital (MGH) in Boston led to a new technique to extend the preservation of rodent liver tissue below zero.
The result was obtained by adding a glucose compound, 3-OMG, and an ingredient, PEG-35kD, to the solution to preserve the tissues, at the base of some antifreeze.
The PEG substance lowers the freezing temperature of the cells and the 3-OMG acts as protection. This allowed the rat livers to be stored at -6°C without freezing them. A process called “supercooling”.
Unfortunately, the process did not work with human livers, which, being 200 times larger, presented a greater risk of ice crystal formation, rendering the organ unusable.
The solution of the problem
In the paper published today in Nature Biotechnology, a research team at Harvard Medical School illustrated three corrective actions that resolved the problem.
First, limit the coolant's contact with air. The team removed the oxygen from the container before pouring the liquid, eliminating any risk of crystals on the external surface of the organ.
Second, two ingredients have been added to the original solution to specifically protect hepatocytes: trehalose helps protect cells and stabilizes their membranes. The glycerol supports the properties of the glucose contained in the original solution.
Third, developed a new method of organ transportation. The previous one involved manually pouring the liquid onto the organ. The actual liquid is more viscous and they used the to pour it perfusion, a method to distribute it in a more uniform and capillary way.
This method will allow organs to travel even over long distances, reaching many more waiting patients.
