Preservation & Cryonics

Chinese researchers developed flexible liquid metal cryoprotectants using eutectic gallium-indium alloys that enable uniform heat transfer and reduce thermal stress by 100-fold, achieving the first successful allogeneic transplantation of a rabbit kidney after vitrification. In vitrification experiments at -196°C, post-rewarming viability of skin tissue increased by 1.7 times and vascular tissues by 3.6 times. This addresses the core vitrification challenge of achieving uniform warming in large organs.

Researchers demonstrated that mouse hippocampal tissue resumes electrophysiological activity after being vitrified at cryogenic temperatures and stored for up to seven days, establishing a protocol for viable brain tissue storage and extending known tolerance limits from hypothermic to cryogenic range. This is the first functional recovery of mammalian brain tissue from true cryopreservation, a critical step toward verifying that neural computation substrates survive the preservation process.

Researchers achieved uniform rewarming at ~88°C/min in up to 2 liter volumes of M22 cryoprotectant using iron-oxide nanoparticles and a newly developed 120 kW radiofrequency coil, successfully vitrifying ≤3L CPA volumes and ~<1L porcine liver. This demonstrates the engineering feasibility of nanowarming at human organ scales, removing a major bottleneck to organ banking via vitrification.

Sparks Brain Preservation published a protocol for aldehyde-based cryopreservation (ABC) of whole human brains using graded immersion in ethylene glycol and sucrose, finding that approximately 10 months is required to reach cryoprotectant equilibration throughout whole human brains. Insufficient equilibration led to ice crystal artifacts in white matter, but after refinement, histology showed preserved cellular architecture and ultrastructure at light and electron microscopic levels. This provides the first practical timeline for human-scale aldehyde-stabilized preservation.

A new bioRxiv preprint demonstrates that both animal and human brains can be cryopreserved by vitrification with M22 cryoprotectant with predominant retention of ultrastructural integrity without prior aldehyde fixation, though severe dehydration occurs. Electron microscopy showed dehydrated but predominantly intact cells, neuropil, and synapses with no ice crystal damage. This challenges the assumption that fixation is necessary for high-quality structural preservation, opening a route that might preserve reversibility.

Cryobiologist Greg Fahy studied rewarmed pieces of gerontologist L. Stephen Coles's brain, cryopreserved in 2014 and stored at -146°C at Alcor, finding the brain is 'astonishingly well preserved.' This is the first published examination of a human brain after over a decade of cryogenic storage at a cryonics facility, providing direct evidence of long-term structural stability.