The Alcor Life Extension Foundation, most often referred to as Alcor, is an American nonprofit, federally tax-exempt, 501(c)(3) organization based in Scottsdale, Arizona, United States. Alcor advocates for, researches, and performs cryonics, the freezing of human corpses and brains in liquid nitrogen after legal death, with hopes of resurrecting and restoring them to full health in the event some new technology can be developed in the future. Cryonics is regarded with skepticism within the mainstream scientific community and has been characterized as quackery and pseudoscience.As of April 30, 2021[update], Alcor had 1,832 members, including 182 who have died and whose corpses have been subject to cryonic processes; 116 bodies had only their head preserved. Alcor also applies its cryonic process to the bodies of pets. As of February 13, 2009[update], there were 33 animal bodies preserved.
Studies of whole brain cryopreservation are rare but are potentially important for a variety of applications. It has been demonstrated that ultrastructure in whole rabbit and pig brains can be cryopreserved by vitrification (ice-free cryopreservation) after prior aldehyde fixation, but fixation limits the range of studies that can be done by neurobiologists, including studies that depend upon general molecular integrity, signal transduction, macromolecular synthesis, and other physiological processes. We now show that whole brain ultrastructure can be preserved by vitrification without prior aldehyde fixation. Rabbit brain perfusion with the M22 vitrification solution followed by vitrification, warming, and fixation showed an absence of visible ice damage and overall structural preservation, but osmotic brain shrinkage sufficient to distort and obscure neuroanatomical detail. Neuroanatomical preservation in the presence of M22 was also investigated in human cerebral cortical biopsies taken after whole brain perfusion with M22. These biopsies did not form ice upon cooling or warming, and high power electron microscopy showed dehydrated and electron-dense but predominantly intact cells, neuropil, and synapses with no signs of ice crystal damage, and partial dilution of these samples restored normal cortical pyramidal cell shapes. To further evaluate ultrastructural preservation within the severely dehydrated brain, rabbit brains were perfused with M22 and then partially washed free of M22 before fixation. Perfusion dilution of the brain to 3-5M M22 resulted in brain re-expansion and the re-appearance of well-defined neuroanatomical features, but rehydration of the brain to 1M M22 resulted in ultrastructural damage suggestive of preventable osmotic injury caused by incomplete removal of M22. We conclude that both animal and human brains can be cryopreserved by vitrification with predominant retention of ultrastructural integrity without the need for prior aldehyde fixation. This observation has direct relevance to the feasibility of human cryopreservation, for which direct evidence has been lacking until this report. It also provides a starting point for perfecting brain cryopreservation, which may be necessary for lengthy space travel and could allow future medical time travel. ### Competing Interest Statement The authors have declared no competing interest.
Biostasis has the potential to extend human lives by offering a bridge to powerful life extension technologies that may be developed in the future. However, key questions in the field remain unresolved, including which biomarkers reliably indicate successful preservation, what technical obstacles pose the greatest barriers, and whether different proposed revival methods are theoretically feasible. To address these gaps, we conducted a collaborative forecasting exercise with 22 practitioners in biostasis, including individuals with expertise in neuroscience, cryobiology, and clinical care. Our results reveal substantial consensus in some areas, for example that synaptic connectivity can serve as a reliable surrogate biomarker for information preservation quality. Practitioners identified three most likely failure modes in contemporary biostasis: inadequate preservation quality even under ideal conditions, geographic barriers preventing timely preservation, and poor procedural execution. Regarding revival strategies, most respondents believe that provably reversible cryopreservation of whole mammalian organisms is most likely decades away, with provably reversible human cryopreservation expected even later, if it is ever achieved. Among revival strategies from contemporary preservation methods, whole brain emulation was considered the most likely to be developed first, though respondents were divided on the metaphysical question of whether it could constitute genuine revival. Molecular nanotechnology was viewed as nearly as likely to be technically feasible, and compatible with both pure cryopreservation and aldehyde-based methods. Taken together, these findings delineate current barriers to high-quality preservation, identify future research priorities, and provide baseline estimates for key areas of uncertainty.
The ultrastructural effects of prolonged normothermic and cold ischemia on the cerebral cortex of the adult rat were investigated. Complete cerebral ischemia was produced by cardiac arrest and the animals' temperature was maintained at 37°C for periods ranging from 0 to 81 hours before electron microscopy preparation. Electron micrographs of cold cerebral ischemia were generated after stabilizing the rat's temperature at 0°C after cardiac arrest for periods ranging from 0 hours to 6 months. A qualitative examination of the electron micrographs shows structural signatures of energy depletion such as vessel leaking and chromatin clumping after 1 hour at 37°C and after 24 hours at 0°C, followed by synapse degradation after 6 hours at 37°C and 1 week at 0°C. Evidence of advanced necrosis was observed after 36 hours at 37°C and 2 months at 0°C. A deep learning algorithm was introduced that demonstrates the temperature dependence of ischemia-induced ultrastructural changes and that can also successfully distinguish between early ischemic changes and advanced necrosis.
When you earn your crust preserving people who hope for life after death, you receive a lot of flack, but it's worth it, says Max More
We investigated the dynamics of autolytic damage of the cortical neurons in adult brains for 24 hours at room temperature (+20 degrees C) after cardiac arrest. The progressive histological and ultrastructural changes were documented using routine and immunohistochemical staining as well as electron microscopy. Our results demonstrated that there were no autolytic damages in the ultrastructure of cerebral neurons in the first 6 hours after warm cardiac arrest, in agreement with previous studies in other mammals. Interestingly, the activation of caspase-3 was observed in a significant number of neurons of the cerebellum and neocortex 9 hours following cardiac arrest. No significant changes related to autolysis were observed using amnio-cupric acid and Nissl (thionine) staining.
