25. February 2008 · Comments Off on Biostasis through chemopreservation · Categories: Cryonics, Death · Tags: , , , ,

Twenty years ago, Charles B. Olson published an article called “A Possible Cure for Death” in the journal Medical Hypotheses. In it, he favorably compares methods of chemical preservation to cryogenic preservation. Unfortunately, this article provoked no wide discussion or attempts at implementation. As the author notes on his website, other than requests for reprints, “nothing more came of it.” And yet the arguments in it are still sound and just as persuasive today as they were then. Why the reluctance?

Freezing has a certain subjective appeal. We freeze foods and rewarm them to eat. We read stories about children who have fallen into ice cold water and survived for hours without breathing. We know that human sperm, eggs, and even embryos can be frozen and thawed without harm. Freezing seems intuitively reversible and complete. Perhaps this is why cryonics quickly attained, and has kept, its singular appeal for life extensionists.

By contrast, we tend to associate chemical preservation with processes that are particularly irreversible and inadequate. Corpses are embalmed to prevent decay for only a short time. Taxidermists make deceased animals look alive, although most of their body parts are missing or transformed. “Plastinated” cadavers are used to demonstrate surface anatomy in schools and museums. No wonder, then, that cryonicists routinely dismiss chemopreservation as a truly bad idea. Although from time to time chemopreservation is raised as a possible alternative to cryonics (Perry, page 21-24), to this day it has not been given the full consideration it deserves

Part of the confusion around chemopreservation concerns the quality of preservation that is possible with this method. Chemical methods of preservation such as fixation are not only adequate, they have long been the gold standard for biologists studying the structure of cells and the brain. As Olson notes,

The technological advances in the preparation of tissue for microscopy have directly improved the prospects of brain preservation for reanimation. This is not a coincidence: the goals of microscopy and brain preservation for reanimation are fundamentally similar. In both cases, a maximal amount of structural detail is preserved such that information can be extracted.

When fixed immediately and properly embedded in a solid medium, tissue can preserve physical structure indefinitely. The entire brain can begin to be fixed by arterial perfusion within minutes after pronouncement of death. Fixation can be done by hospital pathologists or funeral home specialists. The brain can then be impregnated with a solid-setting polymer so that it becomes fully inert.

But what of reversibility? Olson dismisses the need for reversibility. The information in the brain can be retrieved and run on a different substrate — a new organic or machine brain. However, K. Eric Drexler’s proposal in Engines of Creation, nanoscale mechanical repair, could also apply to chemopreserved brains just as to cryopreserved brains. The damage caused by fixation and embedding might be able to be reversed just as the damage caused by freezing or vitrification, if, in both cases, identity-critical information preserved in the brain has not been lost.

If personal identity is preserved in the brain in physical structures such as synaptic circuits, then we know that chemopreservation can preserve these structures just as well as cryopreservation. In fact, chemopreservation entirely avoids the danger of ice formation and fracturing, which in theory could destroy physical structures in the brain and cause irretrievable identity-critical information loss. While fixatives cause molecular changes in the brain, by crosslinking and denaturing proteins, cryoprotectants also cause chemical damage which must later be repaired. While it is not certain that chemopreservation can preserve all identity-critical information, it is also not certain that cryonics stabilization, cryoprotection, and vitrification preserve all identity-critical information.

For those who accept the method of resuscitation by scanning the brain and running it its processes on a different substrate (“mind uploading“), chemopreservation might present additional benefits. The chemopreserved brain, unlike the cryopreserved brain, is ideally suited to microscopic extraction of information:

The molecules in a chemopreserved brain have been extensively crosslinked and can be embedded in a plastic which was designed for electron microscopy. Consequently they will be resistant to the heat and damage generated by whatever beam of particles (or other investigative device) is used to determine the details of the internal structure. In contrast, a frozen brain is not particularly prepared to resist damage, and is acutely sensitive to any heat generated.

But even for those who prefer mechanical repair of the brain, chemopreservation presents benefits that cryopreservation does not.

First, it is potentially cheaper, because it does away with the need for expensive long-term care. Chemopreserved patients would not require labor to keep them in the same condition, other than storage in a secure, designated area, unlike cryopreserved patients who are in continual danger of thawing. Cryopreserved patients require continual monitoring of liquid nitrogen levels and topping off with more liquid nitrogen, as well as special, expensive containers that can hold liquid nitrogen, and these containers need regular maintenance, repair, and replacement. Liquid nitrogen also presents hazards that require continual air monitoring and alarms.

The basic techniques for chemopreserving a brain — fixation and polymer impregnation — would also not require the services of specially trained volunteers or professionals; they are routine techniques used in hospital pathology labs and departments of anatomy around the world. As Olson notes, “the cost of brain chemopreservation could be less than that of a typical funeral.”

People are routinely turned away from cryonics providers because they cannot afford cryopreservation. So what are we waiting for?

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