The study find that the a new method for super-cooling human donor livers to subzero centigrade temperatures without freezing can triple the time that a donor organ stays safe and viable during transportation from the donor to the recipient. This development could greatly expand the availability of healthy livers for transplantation, improve organ utilization, and reduce some of the time pressure on procurement and transplantation teams. This breakthrough addresses a dire need: because of the current donor organ shortage only about 36,500 of the 730,000 patients with fatal end-stage organ disease receive a life-saving organ transplant each year in the U.S.
Improving donor organ
The technique developed by Reiner J. de Vries, MD, Shannon N. Tessier, Ph.D., and Korkut Uygun, Ph.D. from the Center for Engineering in Medicine at Massachusetts General Hospital (MGH) ;and Harvard Medical School, and their colleagues is describ in Nature Biotechnology. Currently; a donor human liver is kept only about nine hours outside the body store on ice in a preservative solution at temperatures ranging; from four to eight degrees C ;(39.2 to 46.4 degrees F); before the tissues become irreparably damaged and the organ has to be discarded.
At colder, subzero temperatures the organ would survive longer; however freezing causes serious damage. This is similar to the damage deep frostbite can cause to skin and extremities and; would make the organ not transplantable. But as the MGH investigators previously demonstrated with rat livers; it’s possible to “supercool” them to -6 °C (21.2 °F); without causing injury to the tissues, extending their preservation time from a matter of hours to a matter of days. The technique is hailed as an “awesome technology” by National Institutes of Health Director Francis Collins, MD, Ph.D. in his “Director’s Blog.”
Difficult to prevent ice formation
“With supercooling, as the volume increases it becomes exponentially more difficult to prevent ice formation at sub-zero temperatures;” de Vries says. “So before; there were a lot of experts who said ‘well this is amazing in small rats, but it will not work in human organs’ and now we have successfully scaled it up 200 times from rat to human livers; using a combination of technologies.”
Prior to supercooling; the livers are condition to protect them from the cold with a preservative “cocktail” that is deliver via machine perfusion; another technique already in use to improve organs for transplantation. The perfusion ensures that the preservative solution is evenly distribute throughout the organ. The human livers can then be transported at -4 °C (24.8 °F), and at the transplantation site machine perfusion is again used ;to carefully warm the livers and bring them out of their state of suspended animation.