Human cryopreservation is an advanced medical research procedure that uses cryoprotective agents and extremely low temperatures to put a body into biological pause with as little freezing as possible. Most human cryopreservations performed today are whole body cryopreservations. However, Tomorrow Bio has decided to add an option for brain-only cryopreservation. We’re going to break down what brain cryopreservation is and why Tomorrow Bio has decided to offer it. We’re looking forward to discussing the topic with the community, please reach out to us with comments and questions. 

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What is Brain Cryopreservation?

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Tomorrow Bio’s standard cryoprotection procedure includes perfusion of cryoprotectants (medical grade anti-freeze) through aortic cannulation. This removes the blood and most of the water from the body and prepares it for extreme subzero temperatures with as little freezing as possible. The amount of ice formation and in turn the quality of preservation is, as of now, primarily determined by ischemic time (i.e. the time the body was without oxygen). In an average case, there is a good amount of ischemia, so a lot of what we do is focused on how to reduce it. Now, once the patient reaches around -130°C they pass the so-called glass transition temperature and become vitrified. The temperature is lowered even further until they reach liquid nitrogen temperature (-196°C, or around -140°C in the case of ITS), at which point they are placed in a cryogenic dewar filled with liquid nitrogen for long-term care (storage). Patients can theoretically remain in this state indefinitely without any meaningful degradation. 

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The cryoprotection procedure for whole body and brain-only cryopreservation is fundamentally the same aside from two steps. During perfusion in brain-only cryoprotection the descending aorta is clamped, meaning that only the top part of the body is perfused with cryoprotectants. After perfusion is complete the brain is removed from the body for final cool down and storage. Whole body patients are placed in one of four compartments in a cryogenic storage dewar and brain-only patients are placed in a central column.

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Whole Body vs. Brain Cryopreservation

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The goal of whole body and brain cryopreservation is the same: to preserve personality, memories, and consciousness for the eventual restoration of life, if and when future medical technology makes it possible (important: neither option gives a guarantee, cryopreservation just provides a chance. Currently, it is impossible to say how high this chance might be). The current scientific consensus is that personality, memory, and consciousness are all emerging from the structures of the brain. Some hypotheses exist that claim that other parts of the body such as the gut have an effect on a person's mood or personality. While this is true, this part of the body is likely replicable and not unique to a level where it would absolutely need to be preserved.But in an abundance of caution we would always recommend whole body cryopreservation as the preferred option. However, if whole body cryopreservation is economically infeasible to a prospective member, then brain cryopreservation is a good alternative.

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The biggest difference between whole body and brain cryopreservation lies in the cost. Since the descending aorta is clamped during cryoprotection, less cryoprotective solution is needed during the procedure. The cost of transporting the patient to the long-term storage facility by plane (when necessary) is also significantly less expensive for a brain-only patient than for a whole body patient. But the largest price difference between the two options arises from long-term storage. Since it cannot be known when the reanimation of cryopreserved patients might be possible, there can not be a predetermined end date for cryopreservation storage. Tomorrow Bio’s cryopreservation plans include enough funding for long-term care that our patients can theoretically be stored indefinitely. This is possible because the long-term storage funds are managed by a patient care trust which puts the funds into very low risk investments with a yield goal of 1-2% above inflation annually. This return is more than enough to pay for the running costs of keeping patients cryopreserved. One of the main running costs for cryopreserved patients is the refill of liquid nitrogen in the cryogenic dewars. Since a brain takes up significantly less space than an entire body (about 50x less), the cost per patient of refilling liquid nitrogen and all associated costs is much lower for a brain-only patient than a whole body patient. All in all the cost for cryopreservation comes out to 60.000€ for brain-only and 200.000€ for whole body.

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Reanimation Possibilities in Whole Body vs Brain Cryopreservation

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While we can’t say when and in what form the reanimation of cryopreserved patients might be possible, it is unlikely that the entire body is necessary for the restoration of life with the memories, personality and consciousness that the patient had before. Please note, that any such statement is partly speculative as current medical and scientific knowledge does not yet explain the exact basis of memories, personality and consciousness. Nevertheless, it is likely that the brain/connectome is sufficient. 

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In any case potential reanimation would require several steps including comprehensive repair. For more details, please see Cryostasis Revival, written by the nanotechnology expert Robert Freitas. It is one of the most influential books in the cryonics space, detailing how cryopreserved patients could be reanimated with nanotechnology. This part would be the same for whole body preservation as well as for brain-only preservation. 

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While the brain-body connections are unique from person to person to some degree, they are fundamentally similar, so that the rest of the body will likely be replicable in the future. Several basic technologies are being developed or are within reach. Such as Organ printing (https://www.nature.com/articles/s41598-020-70086-y), reconnecting nerves (https://www.sciencedirect.com/science/article/pii/S0301008218301643), artificial blood (https://www.nature.com/articles/nbt1200_1231e) and related technologies. While these technologies are not fully developed today, they are almost certainly farther along than revival technology. And the good news is that there is no time limit to how long a patient can be cryopreserved, so patients can wait in cryopreservation until the right technologies have developed.

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Why We Are Offering Brain Cryopreservation

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Our vision at Tomorrow Bio is to help build a world where people can choose how long they want to live - independent of their location or financial resources. Cryopreservation should be available for anyone who wants it and makes the decision with informed consent - it certainly should not depend on someone's personal wealth. While funding methods such as life insurance policies often make cryopreservation plans more accessible, the 200.000€ price tag associated with whole body cryopreservation is infeasible for many people. One of our primary goals is to bring down the cost of cryopreservation significantly, but this is not a short term project. Inflation and a lack of economies of scale make it impossible to reduce the price today without lowering the quality or long-term stability, which would not be an acceptable tradeoff. That’s why we’ve decided to offer brain-only cryopreservation. 

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Brain cryopreservation, very likely, provides a similar chance for future life extension as whole body cryopreservation, but at a more accessible price. This will give more people the chance to choose cryopreservation. The increased number of people signing up is not just beneficial to the people doing it, but also to the field as a whole. As the human cryopreservation field grows, it will reap three main benefits: increased stability, cost reduction, and more research. The growth of any field typically leads to increased stability as more people become invested in its success. It also leads to greater economies of scale which could significantly reduce the cost of both whole body and brain cryopreservation. Lastly, it allows more resources to be dedicated to research. In the short term, more research can improve the quality of cryopreservation procedures and give members a better chance at future reanimation. And in the long term, research can help to develop the reanimation procedure that could give patients the chance to live again.

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We would like to stress again that any cryopreservation is an experimental procedure without concrete proof regarding if and when it will be possible to reanimate a cryopreserved patient. Nevertheless, we would recommend whole-body preservation whenever possible. This does not mean that brain-only preservation is “bad”, but it is not our primary recommendation for an abundance of caution. Of course, it is always possible to switch brain-only preservation contracts to whole-body preservation contracts (and the other way around).  

Please do not hesitate to reach out if any questions arise. We are always available. If you're interested, you can learn more about brain cryopreservation and get a price estimate for a brain cryopreservation plan.