Words

“I wish it were possible … to invent a method of embalming drowned persons, in such a manner that they may be recalled to life at any period, however distant; for having a very ardent desire to see and observe the state of America a hundred years hence, I should prefer to any ordinary death, being immersed in a cask of Madiera wine, with a few friends, till that time, to be then recalled to life by the solar warmth of my dear country.”

- Ben Franklin

Introduction
This is the first in a series of Big Articles that will cover cryopreservation and discuss possible future events that may make it feasible to revive cryonically suspended humans.

You can’t spend very much time reading about futurology without running across mention of “medical time travel” - having one’s body (or just one’s head) placed into cold storage just after the heart stops beating. People have been doing this since the 1960s. What is the outlook for actually bringing any of these people back? Well, one thing’s for sure - we all know the chances of coming back for those who are not thusly preserved.

There are several organizations which, for a fee, will preserve your head and/or full body. The organization I’ve studied the most is Alcor, which claims to be the foremost human cryonics provider. There are other cryonics organizations, of course, and a cursory Google search will turn them up. Be forewarned: I think they must have cryogenically preserved the webmasters who created these sites circa 1996, as their designs are mostly throwbacks to that era, and much of the online material appears to be stale by a few years.

I requested Alcor’s information packet by mail and have read most of the materials inside, which include: a letter to prospective members; a black-and-white glossy concerning Dramatic Advances in Brain Preservation at Alcor Foundation; a large-format “pamphlet” with a short introduction to the concept of cryonics and the company itself; a normal-sized pamphlet about becoming an Alcor member; a membership application (and addressed envelope for same); a memo to applicants about the signup fee; a vinyl Alcor sticker, and finally, a 100-page softbound book with a footprint of roughly 8 1/2 x 11 inches. (The entire book is available as a PDF, sans pictures.)

Why go with cryopreservation?
If you have an inoperable disease, or some terminal illness - or if you are simply getting on in your years - you may not live long enough to benefit from nanomedicine and other future technologies. These inventions may very well give humanity the ability to cure ANY disease, including the biggest killer of all - aging. Yes, aging. If we can manipulate cells at the molecular level, and rewrite DNA itself, there is no reason why we can’t do just that. These are some of the biggest hitters projected for the Singularity. Wouldn’t it be terrible to die of old age just before humankind eradicates aging itself, or of some disease that might soon have been cured with nanomedicine? It would be a huge waste. Cryopreservation offers the only plausible solution that I know of: Putting the body (or the brain, at the very least) into suspended animation, based on the projected capabilities of nanomedicine.

Why NOT go with cryopreservation?
Maybe you’re content with the concept of getting old and gray and dying. Maybe you think it would be impious to reach out for eternal life in this world rather than passing to the next (assuming it exists.) Maybe you’ll live long enough to see the elimination of disease and old age. Maybe you will die in a foreign country and simply decay too much by the time the rescue team can get to you. Maybe you’ll get Alzheimer’s and your brain will turn into mush long before your heart gets around to stopping. Maybe nanotech and medicine will not develop to the point necessary to retrieve cryosuspended individuals. Maybe it’s a huge waste of money (or perhaps you don’t have enough.) Certainly, there are many pros and cons that a prospective patient must evaluate before making the decision to arrange for cryosuspension.

At the Moment of Death
As soon as the patient’s heart has stopped, their body must be cooled as quickly as possible to slow the process of decomposition. Optimally, the patient flatlines in the presence of a cryonics “rescue team” which immediately begins to cool the body. Some organizations will begin to flush out the blood system immediately with glycerol (see the next section.) Alcor has a few different methods they use, depending on whether the patient has died near their facilities or elsewhere. They may put the patient on a heart-lung machine to restore life support for a time. For transporting the patient to their facilitity, they may flush out the circulatory system, replacing blood with a metabolic support solution.

Perfusion and Vitrification
The actual business of cryopreservation currently revolves around the practice of vitrification. The patient’s full body (or just their head) is perfused - that is, their blood is flushed out and replaced - with glycerol. This helps to suppress the formation of ice crystals, which tend to cause severe damage wherever they form. When that happens, huge voids are ripped around arteries and cells can be seen to have lost their membranes. Significant research has been conducted into determining the best sort of glycerol to use (as glycerol itself is available in different molar weights.) A few years ago, Alcor switched to a solution that produces “virtually” (quoting them here) no ice damage. The idea behind using glycerol is that A) it is dehydrative, and B) it gets in the way of water molecules so effectively that they can’t get together fast enough to form ice crystals.

After the circulatory system has been flushed with glycerol to the desired extent, the process of “temperature descent” can begin. The patient is cooled to the glass transition temperature - roughly the boiling point of liquid nitrogen - at which point the entire preserved biostructure is immobilized. All metabolic processes (including those of the microorganisms attempting to decompose the body) are halted, and as long as the patient is maintained at that temperature, no appreciable change in structure is likely to occur for hundreds of years (possibly longer.)

There is an important distinction to note here: Vitrification is not freezing. Freezing is something that can be done with water, or with something that contains a significant amount of water. Vitrification brings the entire biostructure to a glasslike state instead.

Ischemic and Reperfusion Damage
Ischemia is a state in which blood flow is greatly reduced or stopped completely. Obviously this causes tissue damage. If you have ever had an arm or leg “go to sleep” - and you have - that limb has actually undergone ischemic damage. Fortunately, this sort of damage is easily repaired when it happens to muscle and skin tissue, as long as the length and extent of ischemia isn’t too great. The brain, however, has a tougher time of it. White matter is capable of repairing itself to a certain extent, but gray matter is not. Once those cells run out of oxygen, they die.

Reperfusion damage happens as a result of flooding tissues with oxygen after they have depleted their supply of it. The high concentration of oxygen actually oxidizes the tissue somewhat. I’m not certain, but there may also be some damage from restoring hydraulic pressure after it has been totally lost.

In any case, ischemic and reperfusion damage must be repaired before the patient can be revived. The belief is that future nanotech will be able to handle this satisfactorily.

The full body, or just the head?
This is a fairly complicated question. Do we preserve the whole body, or just the head? There are advantages and disadvantages to both schemes.

Full Body

• More expensive
• Harder to perfuse the body as quickly thoroughly as the head alone; there are viscosity limits that get in the way
• “Muscle memory” may be better preserved if the entire body is kept
• The shock of being revived may be less if the patient is still in the same body they remember; age can be regressed (or the entire body replaced with a fresh clone) at a later stage
• Preserving an old, diseased body may be less efficient than simply cloning a new one

Head Only (i.e. “Neurosuspension”)

• Less expensive
• Easier to perfuse a head to the desired concentration
• Assuming the patient wishes to resume life in the normal fashion, a whole new body would need to be cloned
• If the patient wishes to be “uploaded” and run in a computer, preserving the whole body is probably a waste; any avatar (representation of themselves) they might want to use in a virtual world could either be synthesized by DNA analysis or simply put together from old photographs and other biometrics
• Any peculiarities of the original body - that is, things influenced by environmental factors, such as specific shape, scars, tattoos, etc. - will not be present in the cloned body, and may make the patient feel somewhat alienated when they are revived
• It may be simpler to clone a new body and artificially age it to some biological state (e.g. a few years after the end of adolescence) than to reverse the aging process in an old body, not to mention repairing damage caused by any diseases

The Long Wait
After the patient has undergone temperature descent, and been stabilized at liquid nitrogen temperatures, the “medical time travel” begins. How long will it be until we have nanomedicine capable of repairing damage from ischemia and vitrification, let alone restoring the biostructure to normal operating temperature while restarting the metabolic fire and bringing the patient’s brain up to a safe operating state? It could be a long time. Decades, maybe. Perhaps even a century, but at the current level of development I suspect it won’t be that long. Of course the world will have to avoid destroying itself and our societies will have to remain prosperous enough to maintain funding into medical and nanotech research.

What motivations will future society have to bring back these Rip van Winkles? Why will medical science develop technologies that will enable us to retrieve cryosuspended humans? I will discuss these questions in my next Big Article.