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Ischemia and how it affects cryonics.
You may have heard of the word ischemia being used to describe certain medical conditions. Terminology like ‘ischemic heart disease’ and ‘ischemic stroke’ are serious medical conditions, which can sometimes prove fatal. So, what has this to do with cryonics? A lot, actually. Ischemia plays a significant role in making sure high-quality human cryopreservation is carried out, and is one of the reasons why a ‘fast response’ is so important. This article will explore the impact of ischemia, what it means for members, why timing is critical, and why it’s one of cryonics' biggest enemies.
Cells use oxygen to carry out basic functions in the body, like powering muscles and moving materials in and out of cells. Cells harness the energy stored in food into a usable form - a process known as aerobic cellular respiration. During this process, glucose and oxygen convert into carbon dioxide and water, and the energy is transferred into a compound known as adenosine triphosphate (ATP). When there is an inadequate supply of oxygenated blood, this is known as ischemia. Once the oxygen supply stops, cells change their activity from aerobic (with oxygen) to anaerobic (without oxygen). Once the cells can no longer survive in this state, they enter what’s known as “autophagy”, meaning “self-eating,” where they consume their own proteins until they die.
Ischemia is often a consequence of arteriosclerosis, atherosclerosis, and thrombosis. Arteriosclerosis is where the blood vessels that carry oxygen and nutrients from the heart to the arteries become thick and stiff, causing a restriction of blood flow to organs and tissues. Atherosclerosis is a specific type of arteriosclerosis, and is a buildup of fats, cholesterol and other substances in and on the artery walls. This buildup is known as plaque, which causes arteries to narrow and can lead to blood clots. Finally, thrombosis occurs when blood clots clog a person’s blood vessels - either a vein (veinous thrombosis) or artery (arterial thrombosis).
So, why is ischemia a problem? In cryonics, the fewer cells—particularly cells like neurons and glial cells in the brain—that die before cryopreservation begins, the better quality procedure for the patient. If a patient is revived in the future, the information stored in their brain is better preserved the lower the ischemic damage. This is central to the work and research of cryonics, as the brain is what makes you, you, and any damage caused to it could impact a member’s chance of a future revival.
Specialized standby teams known as SST (standby, stabilization, transport) need to act fast in order to mitigate cellular decay. Once legal death has been pronounced, the SST team steps in to lower the patient’s temperature as quickly as possible. The patient is placed in a state of hypothermia, thereby decreasing the metabolic rate. When the metabolic rate is reduced in the body, so does a cell's need for oxygen, to mitigate cell damage.
While this happens, the team uses an automatic chest compression device to provide cardiopulmonary support (CPS) and administer drugs. This device prevents oxygen from stagnating in the body and helps keep the blood circulating and the cells oxygenated, assisting an efficient cooling process. The swift interception of the SST team and the implementation of procedures can help bring down ischemia as much as possible. At this point, the body is perfused with cryoprotective agents (CPAs). These help prevent ice crystals formation in the tissues at sub-zero temperatures. When the core temperature is lowered to about -120 degrees, the body enters a glass-like state and becomes vitrified. Only at this point does the risk of ischemia end, as metabolic activity is essentially ‘paused’ and with it the cells' need for oxygen.
As mentioned above, the absence of blood flow (and thus oxygen) is called ‘ischemia’ - or ‘warm ischemia’ if the organ isn’t cooled. Cold ischemia is a result of the cooling of the organ to increase its lifespan after being removed from the body. Current medical knowledge states that prolonged warm ischemia leads to irreversible damage to the body and the brain, however, this may not be completely accurate. Studies in recent years have proven that cell death could in fact be recoverable, but the research still has a long way to go.
At the yearly Biostasis conference, co-founder of International Cryomedicine Experts (I.C.E.) Eric Vogt discussed the biggest challenges facing SST teams today. He covered optimal cryopreservation situations, and that time and temperature are critical to a successful SST and in avoiding ischemia damage. Vogt discusses that the difficulty facing cryonics today is when and where death occurs, how and when they are pronounced legally dead, and how quickly an SST can get to a patient’s bedside.
Advanced Neural Bioscience (ANB) is an American company founded in 2008 by Aschwin de Wolf and Chana Phaedra. The intent of the company was to improve the science and technology surrounding cryonics. So far, the company has identified areas of improvement by implementing protocols that can decrease the cell’s need for oxygen and improve blood flow after ischemic events.
Having done significant research in the areas of cryoprotective agents and cerebral ischemia, the founders have noted the need for cryonics to become a medical elective in order to combat ischemia damage. Right now, companies can only strive to do their best to minimize damage, which is particularly important for cryonics companies that do not offer standby and stabilization services. When third-party services have to be deployed in these circumstances, the founders of ANB believe that a patient could expect at least 24 hours of cold ischemia, preceded by periods of warm ischemia. Thankfully, Tomorrow Bio offers an all-inclusive service, with fully trained and equipped standby teams available 24/7 to help reduce ischemic damage as much as possible.
Tomorrow Bio and EBF are always looking to develop and improve current technologies, ensuring that members receive an optimal cryopreservation procedure. Presently, Tomorrow Bio’s research objectives include perfecting perfusion protocols and procedures, optimizing cryoprotective agents, and providing support and training to local teams, among many other initiatives.
EBF’s research projects focus on improving the handling of non-ideal ischemia cases with different degrees of ischemic damage. Approaches include trialing different cryoprotective agents (CPAs), perfusion techniques, decompressive craniotomies, medication, and more. Research is also being carried out by Tomorrow Bio regarding logistical optimization to reduce ischemia in the first place.
We can’t always predict death. While Tomorrow Bio hopes for optimal scenarios, challenges can arise. Although it’s difficult to completely avoid ischemic damage, Tomorrow Bio’s standby team does its best to ensure they carry out the highest-quality cryopreservation with the shortest possible delay. Hopefully, as technology advances, cryonics companies will see the introduction of new devices or methods to help avoid ischemic damage altogether.
If you’d like to know more about the exciting research happening in the biostasis world or are just interested to learn more, why not check out Tomorrow Insight, filled with great information and articles! You can also join in on the discussion on our Discord server to chat all things cryonics! If you think you’re ready to sign up today, you can do so on the website at Tomorrow Bio.
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