Any cell that has ever survived freezing or vitrification has recovered from imperfect preservation. Cells cooled below -100ºC enter an alien state in which most cell water is replaced by solutes, molecules deform from normal shapes, and even cell membranes undergo phase transitions. After warming and removal of cryoprotectant, cells engage in considerable self-repair before operating normally again.
It is a premise of cryonics that natural self-repair is not all that will ever exist in medicine. And indeed, it already is not, since molecular intervention in cell death following cryopreservation has already begun in mainstream cryobiology. Cryonicists have been envisioning cell repair augmentation by drugs, synthetic enzymes, viruses, and macrophages since the 1960s. These ideas, part of a biological tradition of diffusion-driven chemistry, are now termed “wet nanotechnology”. In the 1980s, a new type of nanotechnology based on positional control of chemical reactions was proposed in a mechanical tradition. The utility of such technology in cryobiology was recognized early.
Today the potential of wet and dry nanotechnology in medicine is collectively termed “nanomedicine”. According to the U.S. National Institutes of Health, nanomedicine will eventually bring “synthetic biological devices” that could heal diseases and “fix the ‘broken’ parts in the cells”. Any honest scientific assessment of the utility of long-term preservation, be it gametes from an endangered species or an entire human being, must consider the impact of future technology.
Exactly what technology is expected? Since preservation can be continued indefinitely, even centuries, one must consider the limits of what is physically possible. It’s already known that every tissue and organ in the body can in principle be regenerated. The most elegant application of such technology will be in situ regeneration of injured tissue, including regrowth of lost limbs and organs. For treatment of severe traumatic injuries, it’s theoretically possible that even an entire body could be regenerated around an unconscious brain maintained in a fluid life support system.
The brain must be repaired, not replaced. If mature nanotechnology is assumed, then very sophisticated repair strategies can be envisioned as explained in the references below. In the worst case, it’s theoretically possible to scan the entire molecular structure of a cryopreserved brain into a computer for analysis and direction of repair processes. For cryopreservation under good conditions with modern technology, and without fracturing, less extreme forms of cell repair should suffice.
Cell Repair and Nanomedicine References
Molecular Repair of the Brain
“Realistic” Scenario for Nanotechnological Repair of the Frozen Human Brain
Nanomedicine Book Site
24th Century Medicine (biological paradigm)
Engines of Healing (mechanical paradigm)