In the history of cryonics we can identify a number of major technological developments: the introduction of cryoprotectants to reduce ice formation, the use of mechanical chest compression devices to restore brain perfusion and accelerate cooling, comprehensive multi-modal medications protocols to mitigate warm ischemia and favor good cryoprotective perfusion, remote blood washout with an organ preservation solution to protect against cold ischemia, closed-circuit cryoprotective perfusion to reduce osmotic damage, and, of course, the introduction of vitrification agents to eliminate ice formation altogether.
What are the kinds of major technological developments that we can expect in cryonics in the foreseeable future? When we talk about technological progress we should distinguish among advances in medical science that simply require implementation in cryonics, advances in medical science that require various degrees of modification to be used in cryonics, and technological developments that are conceived and developed within cryonics. These distinctions are important to recognize because they can tell us whether new advances “simply” require acquiring these technologies or whether an ambitious research and development program needs to be launched to validate, develop, and introduce these technologies.
The three most important future technological advances that I can foresee are:
1. Liquid ventilation (cyclic cold lung lavage). Currently there are two basic modes of cooling in cryonics: (a) external cooling in an ice bath and (b) internal cooling with an organ preservation solution. Considering the harmful effects of warm ischemia on the structure of the brain and distribution of the vitrification agent, it is very important to introduce a rapid method of initial cooling that does not require surgery and can approximate the rates of internal cooling. The most potent candidate here is liquid ventilation in which a cold perfluorocarbon is pumped in and out of the lungs to accelerate cooling of the patient.
2. Intermediate temperature storage (ITS). As vitrification eliminates ice formation, fracturing remains the only mechanical form of injury in contemporary cryonics. The most obvious solution is to store patients below the glass transition temperature ((‑123°C for the M22 vitrification solution) but not so low as to induce fracturing. Functional neuro ITS units have been built and detailed designs for whole body ITS units have been developed. Concerns that have not been fully addressed yet include optimal storage temperature and cost. The most pressing practical question at this point is whether fracture-free storage may be possible at liquid nitrogen temperatures if ischemia-induced ice formation is eliminated and a proper cooling protocol is used. Also, would it possible to eliminate the need for ITS altogether if a cold gas is circulated through the patient’s circulatory system instead?
3. Opening the blood-brain barrier. It has been well established that under good conditions loading of the vitrification agent produces severe dehydration of the brain. While dehydration may not substantially alter brain structure, it is a problem in terms of maintaining viability of the brain and producing good electron micrographs. We now know of a number of agents that can modify the blood-brain barrier to allow cryoprotective perfusion without severe dehydration. Current concerns include whether such agents produce edema in other parts of the body, what the optimum protocol and dosage should be for humans, and whether the use of such agents reduces or favors ice formation in ischemic brains.
Other conceivable advantages that can improve cryonics include lower toxicity vitrification agents, drugs that can substantially reduce metabolism in the brain, and integration of brain imaging and cryoprotectant perfusion.
Originally published as a column in Cryonics magazine, April, 2014