We’re closer than ever to freezing organs and making transplant waitlists a thing of the past
According to UNOS, the United Network for Organ Sharing, 20 people in the United States die every day because they are unable to receive an organ transplant. Unfortunately for the 115,000 people in the country awaiting an organ transplant, a successful transplant currently relies more on being in the right place at the right time than it does on finding donors.
An organ transplant needs to happen quickly for there to be any chance of success. Hearts and lungs need to be transplanted in six hours, a liver or pancreas in 12 hours, and a kidney in 30 hours. This does not leave doctors, nurses, and surgeons much time to match an organ, transport it, prepare the recipient for surgery, and ultimately finish the transplant. Thus, the pursuit of successfully freezing and thawing organs that remain functional is of critical importance.
Frozen in Place
Cryobiologists have been working on a solution for the preservation of human organs since the Seventies. Vitrification, the process of transforming a substance into a glass-like solid, has so far been the go-to method. At first, the challenge was freezing human tissue to the temperature at which molecular activity comes to a halt—a frigid 120 degrees below zero Celsius.
Freezing tissue to such levels typically causes blood vessels to burst, which would make an organ unusable in a transplant. An early attempt at solving this issue was flushing water out of the organs using organic compounds, allowing vitrification without blood vessels bursting. However, the toxicity of the compounds used rendered the organs useless.
Researchers were eventually able to use cryoprotectants to “supercool” biological tissue to temperatures well below the required temperature, potentially solving part of the problem.
Cryoprotectants are substances that protect living tissue from damage when frozen. Found in nature, it’s what safeguards fish, amphibians, and even insects who live in the harsh environments of winter in the Arctic and Antarctic.
A far cry from the wishful thinking of Dr. James Bedford, the late Berkeley professor who was the first person to have his dead body frozen with the hopes of being revived in the future, vitrification offers hope for preserving organs—if they can be frozen without the use of toxic solutions and properly thawed.
Warming Up
Discovering a way to thaw organs has proven equally tricky, if not more so. The process of warming a frozen organ results in the formation of crystals. These crystals can “crack” the organ, causing devastating harm that makes it unable to be transplanted.
The proposed solution is to find a way to quickly heat frozen organs so there is no time for the crystals to form. Attempts using microwaves (electromagnetic waves with a wavelength between infrared and radio waves, not the kitchen appliance) were fruitless, despite rapidly heating frozen organs. The problem with microwaves was their uneven heating, leaving parts of the tissue with hot spots.
In spring of 2017, a team of engineers, biologists, radiologists, and chemists from the University of Minnesota, Carnegie Mellon University, and Clemson University studied the effects of using magnetic nanoparticles to heat organs. They chose commonly found iron oxide particles which, after modification to keep them from all sticking together in the organ’s cryoprotectant, were able to create an inductive heating system.
This heating system has been successful in heating small areas of tissue but has caused damage in larger organs. The nanoparticles surround a tiny coil in the organ, placing them inside a magnetic field which creates heat. The heat spreads from its source at the center of the organ to its edges.
So far this has led to uneven heating and damage when dealing with larger organs, however, the researchers believe they can make small adjustments and eventually scale up to human-sized organs. They’ll begin with rabbit organs, moving on to pigs, then ultimately to human organs.
A New Breakthrough
Meanwhile, Arigos Biomedical is moving full steam ahead in efforts to find a way to make human organ banking a reality. The company, the first organization to receive funding from the Thiel Foundation’s Breakout Labs, has already made some very significant strides.
Stephen Van Sickle, the co-founder and CSO of Arigos, came across old research which had been previously abandoned concerning a novel way of achieving vitrification. The idea was to flush an organ’s veins and arteries using a gas. Van Sickle and the team at Arigos experimented with inert helium and the results were encouraging, to say the least.
Using an inert noble gas like helium meant that it would not be toxic to the organ like some of the other compounds previously used in vitrification. Furthermore, the gas in its veins and arteries doesn’t freeze, allowing the organ to move as it is frozen, preventing the cracking that historically has plagued other efforts.
Arigos has already recovered pig hearts from the 120 degrees below zero threshold and is hoping to attempt a complete transplant on a pig in 2019. If successful, the organization will approach the FDA to get approval for human trials the following year.
Banking on It
Even if Arigos is successful in having human trials authorized, and the trials are successful, it likely will take at least another five years for full FDA approval. Still, at the rate progress is being made towards a future of organ banks ready to supply those in need of an organ transplant, the outlook is bright.
Although it’s certainly too late to revitalize Ted Williams’ frozen head, this provides significant hope for the 115,000 Americans awaiting an organ transplant.
