Cryopreservation of whole organs may be a transplantation game-changer

Human organs, once removed from their owner's body, are very fragile things. As reported in Science (News, June 21, 2023), this poses a problem for transplant medicine:

The rapid decay of organs is one of the biggest problems bedeviling organ transplants for people. From the moment a human heart or lung is disconnected from a donor, doctors have 4 to 6 hours to get it hooked up to a new patient’s blood supply before it is irretrievably damaged. For a liver, the window is 8 to 12 hours. For a kidney it’s about 1 day.

The effort to cut the warm ischemic time between organ removal and successful implantation has transformed the legal landscape for organ transplantation. 

• It was one of the reasons for the development of "brain death" in 1968 -- waiting around for a patient with no brain function to lose all cardiopulmonary function often led to the loss of organs that start to deteriorate while still in the patient's body. It may not have been "a driving force" behind the 1968 recommendation of a Harvard Ad Hoc Committee, but it surely benefited the transplant industry and certainly escaped nobody's attention at the time. The 1968 recommendation was crucial to the development of the Uniform Determination of Death Act.
• It was the reason for widespread adoption of UNOS policy and hospital protocols for "Donation After Cardiac [or "Cardiopulmonary" or "Cardiac and Circulatory" or "Controlled Cardiocirculatory"] Death" ("DCD" or "DCCD"). Careful timing and choreography of the removal of life support, determination of death, and organ retrieval can reduce warm ischemic time dramatically. No new law was needed to make this legal, but DCD provoked a vigorous debate about a practice that involved inducing death, withholding life-saving and life-supporting measures, and deeming a patient to be dead while autoresuscitation might still be possible (multiple citations are available on PubMed; here's one).

The latest wrinkle in technology's advance to the frontiers of medicine and law was reported in a Science news report this past week (citation above). A team at the University of Minnesota took a kidney out of white lab rat, stuck it into a deep freeze (-150ºC), and then successfully transplanted the organ into a recipient rat. Within minutes, the once-frozen kidney began producing urine -- according to the young surgeon who produced this result, "First successful transplant of vitrified, nanowarmed rat kidney."

Although still a ways off, the implications of this breakthrough process are vast. Organs that cannot be used immediately -- say, after death has been declared but a donor match cannot be found -- can be frozen for future use. Stockpiling frozen organs could put a real dent in the waiting times experienced by potential recipients on the various organ waiting lists. 

The process won't be quite as straightforward with larger human organs, which take longer to freeze and are harder to squeeze water out of than tiny rat livers. But we now know that it can be done in small mammals, and you can be sure efforts are under way (or soon will be) to scale up to human organs. Stay tuned.