The idea of freezing human beings and defrosting them at some point in the future, or on the other side of the galaxy, is a popular theme within sci-fi writing and cinematic space dramas, but cryogenically freezing humans and keeping them alive for any length of time currently remains out of reach. However, on the microcosmic side of that spectrum, humans have been freezing eggs, sperm and embryos for decades, and millions of children have been born from fundamental cells that had once been frozen.
In other words, one side of the human freezing problem remains unsolved, while the other extreme has been handled for years. The question—and the latest frontier in this industry—is whether it is possible to freeze organs for long-term storage. The speed with which an organ must be moved from donor to transplant recipient is extremely prohibitive, and thousands of people die every year—approximately 20 every day!—because compatible organs are simply not available for them. Which leaves us, again, with the question… is it possible to freeze organs?
Before we dig into the nuts and bolts of that answer, we should understand a bit more about organ function, particularly once it has been removed from a donor.
While the fact that humans have developed the ability to transplant organs is nothing short of miraculous, this wonderful resource still has a number of serious limitations. The most notable one, of course, is the short amount of time that an organ remains viable outside of a host. Pancreas and liver transplants must be completed within 12 hours, while hearts must reach their intended patient within only 6 hours! Given the thousands of patients on these waiting lists, the unpredictability of death, and the additional variables of compatibility, organ transplants are an incredible idea, but a faulty solution.
For those who don’t understand the process of donor organs, a small refresher might be appreciated. When an organ donor dies, typically from an accident or an illness, “brain death” must be confirmed, meaning that there is no further chance of resuscitation or survival by the potential donor. At this point, the person’s other bodily functions are artificially driven, so the organs will remain active. The deceased is then potentially matched with all of the waiting donors in the organ donation pool. Many people refer to these as a list, but in fact, compatibility of the donor and the recipient is far more important. Believe it or not, only about 1% of all organ donors have organs that are compatible or viable for donation at their time of death.
Once compatibility is confirmed, the organ must be biopsied to make sure it is suitable for transplant. If this goes well, then the organ is removed, flushed clean with a preservation solution, then placed in more of this same solution, packed in sterile containers and kept cool, but unfrozen as it takes its fast-break journey to its new home–whether that is a patient in the same hospital or an eager donor at a hospital 200 hundred miles away.
Freezing Donor Organs
That delicate balance of keeping an organ cool, but not freezing it, is central to the main reason why organs have such a short “shelf life”. Back in the 1970s, there was a rather concerted effort to begin freezing organs for this very reason—to extend their life span so more people could benefit. However, there were two intrinsic problems with freezing an organ and expecting it to function after defrosting.
Imagine putting a bottle of beer in the freezer to make it cold fast; if you forget it, the liquid will eventually freeze and expand, causing the bottle to shatter. Now, like every other part of our body, our organs are composed of a high percentage of water. When you freeze that water, it will expand, causing ruptures to blood vessels, as well as cell death, on an even smaller scale, as the tiniest ice crystals would act like pins popping the balloons of cell membranes. The second problem lies on the other side; defrosting a frozen organ would cause the organ to crack or rupture, since it wouldn’t necessarily thaw at the same temperature or in a predictable way. These two critical issues made the idea of freezing an organ merely a fantasy.
For decades, the idea fell out of fashion, research interest dried up, and the same system of rapidly rushing healthy organs in handheld coolers became the norm. Fortunately, the dream of freezing organs never completely died, and recent advancements have breathed life back into this old idea.
The first problem was somewhat easier to solve; simply remove as much of the water as possible by flooding the organ with a concoction of other chemicals and compounds that wouldn’t behave like water when the organ was frozen. Instead of expanding and rupturing, these deep-freeze organs became like glass sculptures—extremely delicate, but not damaged. The second problem, however, was notably harder to solve, but we may be getting close. One team of researchers has recently begun using helium gas to fill in the veins and arteries of an organ, rather than any liquid at all. By using this gas, it allows for the organ to be cooled and preserved, but doesn’t create the same rigidity as a liquid. That way, as the organ is brought back up to a normal temperature, in preparation for implantation, there isn’t a risk of fracturing or rupturing.
This exciting new step forward in the world of organ transplants could be rolled out as early as 2020, once animal tries are completed and human trials are approved by the FDA. If all goes to plan, within a decade, the organ transplant process as we know it may be a thing of the past. With a dedicated bank of preserved organs, people could be matched with an ideal donor organ as soon as they learn they need a new one! More importantly, without the 6-12 hour limit on most donor organ viability, the organs could be more thoroughly matched to potential recipients’ immune system, greatly decreasing the risk of host rejection.
A Final Word
Although freezing organs has remained out of reach for decades, it seems as though the world is ready for a change, and steps are being taken in the right direction. Who knows, by the time you need a replacement organ in a few decades, the idea of waiting lists will be a distant memory and your fresh set of lungs can be air-dropped to you the day after your diagnosis!
- National Institutes Of Health (NIH)
- Organ Donation Alliance
- Scientific American (Link 1)
- Scientific American (Link 2)