A Method of Rapidly Warming Vitrified Organs with Minimal Damage

Today I'll point your attention to a most interesting paper on a novel approach to reviving vitrified tissues. Vitrification is a state induced in tissues through the use of cryoprotectant and very low temperatures. All biological molecular activity halts, and the tissue enters a glass-like state of minimal ice crystal formation in which the small-scale structures essential to function are well preserved, or at least to the extent that the process is performed well and cryoprotectant is completely diffused throughout the tissue. Reversing this process without killing cells and essentially destroying the living tissue is another story, however. It cannot be done reliably today, but seems like a very feasible near future goal. Low-temperature storage of cells and other very small amounts of biological materials is well established, and lower animals such as nematode worms can survive vitrification and thawing. Further, researchers have demonstrated vitrification, thawing, and transplant of a mammalian organ that functioned for at least a short time. These are starting points, and a number of research groups are trying to close the various gaps in reliability and technology to enable a robust methodology.

Reversible vitrification of large tissue sections is an important goal for many reasons. Firstly, it would revolutionize the logistics of the organ transplant industry, which is currently expensive and challenging because organs cannot be kept alive for long once available, among other reasons. Secondly it would similarly revolutionize the logistics of the tissue engineering industry that has yet to exist but lies not so far ahead in our future. The ability to create supplies of tissues and organs far ahead of time and store them safely and indefinitely will shape much of the economics of this field. Lastly, and most importantly for the long term, the cryonics industry needs a way to safely warm the people who have been cryopreserved at death, at some future date when rejuvenation therapies, regenerative medicine, and other necessary biotechnologies have advanced to the point at which it is possible to restore or replace an old body and brain, even working from the starting point of a warming individual just past the point of today's clinical death. These individuals took a brave leap into the unknown, and at some point it will become possible to revive them. Even before that time, concrete progress towards reversible vitrification of tissues will greatly increase the legitimacy of cryonics in the eyes of the world. If a kidney can be vitrified, thawed, and used in medicine, its fine structures intact, then why can't a brain and the mind it contains be preserved, or so the line of thought will run.

In the case of the technology demonstrated here, it would most likely be very challenging to apply it to people already preserved, as it involves additions to the cryoprotectant solution. Introducing those additions after the fact would no doubt require technology of the same order of advancement as would be needed to restore aged tissues and manage a safe return to life on thawing. If there is one approach, however, there will be others - and for the people who have yet to be cryopreserved, those who will age to death prior to the advent of comprehensive human rejuvenation therapies, this class of approach is still very relevant. That this can be done at all should also increase any careful assessment of the odds of the whole endeavor of cryonics succeeding for those involved. Time passes and progress is forged, and more rapidly than ever these days.

New technology rewarms large-scale tissues preserved at low temperatures

A research team has discovered a groundbreaking process to successfully rewarm large-scale animal heart valves and blood vessels preserved at very low temperatures. The discovery is a major step forward in saving millions of human lives by increasing the availability of organs and tissues for transplantation through the establishment of tissue and organ banks. "This is the first time that anyone has been able to scale up to a larger biological system and demonstrate successful, fast, and uniform warming hundreds of degrees Celsius per minute of preserved tissue without damaging the tissue."

In the past, researchers were only able to show success at about 1 milliliter of tissue and solution. This study scales up to 50 milliliters, which means there is a strong possibility they could scale up to even larger systems, like organs. Currently, more than 60 percent of the hearts and lungs donated for transplantation must be discarded each year because these tissues cannot be kept on ice for longer than four hours. Long-term preservation methods, like vitrification, that cool biological samples to an ice-free glassy state using very low temperatures between -160 and -196 degrees Celsius have been around for decades. However, the biggest problem has been with the rewarming. Tissues often suffer major damage during the rewarming process making them unusable, especially at larger scales.

In this new study, the researchers addressed this rewarming problem by developing a revolutionary new method using silica-coated iron oxide nanoparticles dispersed throughout a cryoprotectant solution that included the tissue. The iron oxide nanoparticles act as tiny heaters around the tissue when they are activated using noninvasive electromagnetic waves to rapidly and uniformly warm tissue at rates of 100 to 200 degrees Celsius per minute, 10 to 100 times faster than previous methods. After rewarming and testing for viability, the results showed that none of the tissues displayed signs of harm, unlike control samples rewarmed slowly over ice or those using convection warming. The researchers were also able to successfully wash away the iron oxide nanoparticles from the sample following the warming. Although scaling up the system to accommodate entire organs will require further optimization, the authors are optimistic. They plan to start with rodent organs (such as rat and rabbit) and then scale up to pig organs and then, hopefully, human organs.

Improved tissue cryopreservation using inductive heating of magnetic nanoparticles

Vitrification, a kinetic process of liquid solidification into glass, poses many potential benefits for tissue cryopreservation including indefinite storage, banking, and facilitation of tissue matching for transplantation. To date, however, successful rewarming of tissues vitrified in VS55, a cryoprotectant solution, can only be achieved by convective warming of small volumes on the order of 1 ml. Successful rewarming requires both uniform and fast rates to reduce thermal mechanical stress and cracks, and to prevent rewarming phase crystallization. We present a scalable nanowarming technology for 1- to 80-ml samples using radiofrequency-excited mesoporous silica-coated iron oxide nanoparticles in VS55.

Advanced imaging including sweep imaging with Fourier transform and microcomputed tomography was used to verify loading and unloading of VS55 and nanoparticles and successful vitrification of porcine arteries. Nanowarming was then used to demonstrate uniform and rapid rewarming at more than 130°C/min in both physical (1 to 80 ml) and biological systems including human dermal fibroblast cells, porcine arteries and porcine aortic heart valve leaflet tissues (1 to 50 ml). Nanowarming yielded viability that matched control and/or exceeded gold standard convective warming in 1- to 50-ml systems, and improved viability compared to slow-warmed (crystallized) samples. Last, biomechanical testing displayed no significant biomechanical property changes in blood vessel length or elastic modulus after nanowarming compared to untreated fresh control porcine arteries. In aggregate, these results demonstrate new physical and biological evidence that nanowarming can improve the outcome of vitrified cryogenic storage of tissues in larger sample volumes.

Comments

As I understand this doesn't help any of the patients currently cryopreserved? You have to be cryopreserved with this new solution.

Posted by: Norse at March 2nd, 2017 5:40 AM

@Norse. You're right and Reason covers it in the piece.

I found it interesting that in the media article I read on this that Prof. Bischof (senior author of the paper) felt obliged to say, on the topic of the potential cryonics application of this research, that:

"There is a certain intellectual connecting of the dots that takes you from the organ to the person... I could see somebody making this argument", said Bischof, but added these ambitions were not "science-based" as unlike with organs, the person would already be dead when frozen.

Of course the reason why you currently have to be dead to receive the cryonics procedure is that if you weren't dead already the procedure would kill you, as we define it in current law - as the process is irreversible.

However, should we advance to a point where we can demonstrate that cryonics is reversible in larger mammals followed by humans, then it has to be arguable that those people are living patients, with all the rights an entitlements that go with that.

Proving reversibility of the process would also allow for people to opt for this treatment at a time of their choosing, and much earlier than is currently the case - one of the main issues with cryonics, as it stands, is that it often takes place in sub-optimal circumstances at the very end of life, with a few, thinly spread suppliers around the globe and within a very inconsistent legal framework.

The comments from Prof. Bischof do highlight one of the barriers to cryonics progressing is the long-standing tension between cryobiology and cryonics where people like Prof. Bischof know full well that, subject to it successfully scaling up to larger organs, logically this research may well have potential application in humans - but cryonics is kook science and if you want to be taken seriously you can't directly address it. Another example would be 21st Century Medicine, who won the Brain Preservation Foundation Small Mammal prize last year. Despite winning they still felt obliged to state the following in their press release:

"Although ASC has been discussed in the popular press and even by the Brain Preservation Foundation as a new type of cryonics, in which "revival" might be accomplished by destroying a person's brain and creating a computer simulation of that brain based on the scanning of immense numbers of brain sections to create a comprehensive map of the structure of that person's brain, 21CM does not endorse these views. Others have suggested that ASC preserved brains might be revived by means of biological repairs carried out with future tools from the field of medical nanotechnology, but we do not endorse this view either. 21CM sought the prize to demonstrate the power of its vitrification technology to reach beyond conventional applications of cryobiology and provide unexpected new tools to mainstream neurobiologists. While 21CM firmly believes in personal choice and respects the views of all honest people, we are not a cryonics company and as such do not endorse any form of cryonics."

Despite that rather lengthy caveat it's worth noting that the cryo-protectant that Alcor currently use was developed by and licensed to them by 21st Century Medicine.

Posted by: TheRage at March 2nd, 2017 7:48 AM

@TheRage: Wow, I thought that 21CM were created by cryonics activists.

Posted by: Antonio at March 2nd, 2017 8:43 AM

@Antonio: If they were then that would make the point I was trying to make about those in the field tiptoeing around cryonics for fear of ridicule. That section from 21CM I quoted above takes that to an absurd degree - 21CM entered and won a competition that's stated purpose was to progress the long-term preservation of small mammal brains in order to for them to be later resurrected (either digital or physical), and then they go out of their way to deny that they have any interest in cryonics.

In part I can hardly blame them. I recall the fuss around the preservation of a 14 year old girl last year and the tone of the reporting and commentary on that. There's not a lot to be gained now by being more explicit regards cryonics, and working towards organ preservation accomplishes much of what needs to happen in order to make cryonics more feasible.

Posted by: TheRage at March 2nd, 2017 11:25 AM

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