X-Message-Number: 15210
From: 
Date: Fri, 29 Dec 2000 22:19:44 EST
Subject: Vitrification

VITRIFICATION FACTS AND PROSPECTS

It may be helpful, especially for newcomers or/and those with limited 
technical background, if I attempt some relatively short and easy, yet 
hopefully clear and accurate overviews of vitrification for cryopreservation. 
These will also appear, sometimes in expanded form, on our web site.

First, for those with very limited time, the bottom line:

At present, to our knowledge, there does not exist any proven method of 
vitrifying a human brain (or any mammalian brain) without serious damage. As 
far as we know, there has been not a single reported study of a vitrified 
mammalian brain, cooled to long term storage temperature and then rewarmed. 

There have been reports of encouraging progress; but the samples are very 
small, the evidence is indirect or partial, and there is a dearth of 
verification by independent investigators.   

Nevertheless, although its promise has been unfulfilled for many years, some 
serious people continue to believe that vitrification is the wave of the 
future. We (Cryonics Institute) will continue to monitor the work of others 
and also continue and expand our own research into improved cryopreservation. 
When actual verified results and capabilities are in place--whether for 
vitrification or for improved freezing--we expect to offer our members all 
useful options, either directly or indirectly, using our own or/and licensed 
technologies.
  --------------------
Now, the first instalment of this background series:

The word "vitrification" itself is probably fairly familiar to most readers. 
It means formation of a glass-like state that is "solid" in the sense that it 
does not flow or deform easily, but lacks the clear crystal structure 
characteristic of most pure solids. Water solutions that are vitrified have 
few or small water (ice) crystals.

ADVANTAGES of vitrification over freezing, for human cryopreservation, 
include the fact that fewer or smaller ice crystals should result in less 
mechanical damage by ice crystals, e.g. fewer tears in cell membranes by ice 
crystals formed outside the cells. And if ice crystals tend not to form or 
grow, there should be fewer regions where large ice crystals have disrupted 
the connections between cells and tissues, or have exerted crushing forces. 

(This does not mean that vitrification is the only method of minimizing ice 
damage. Ice damage can also sometimes be reduced by removing water, by 
reducing the freezing temperature, and by other means to limit the amount of 
ice and the size and location of crystals.)

Also, if the vitrification can be accomplished without the removal of too 
much water, there may be less chemical damage. For example, proteins inside 
cells can become "denatured" (chemically changed) if the intracellular 
solution becomes "hypertonic" or has solutes (dissolved substances) in 
concentrations higher than normal. But chemical damage is a complicated 
issue, and involves among other things the question of toxicity of the 
vitrifiable cryprotectant agent (CPA) itself. 

DISADVANTAGES of vitrification include the need (in methods used so far, to 
our knowledge) for very fast cooling, for storage ideally at a temperature 
(in the neighborhood of - 130 C) not easily maintained with great reliability 
with equipment currently available, and for very fast and very uniform 
rewarming to avoid "devitrification" (formation of ice crystals during 
rewarming). 

The above is far from exhaustive, but I want to keep these instalments short. 
More will follow as time permits, including summaries of recent patents and 
professional publications. 

Robert Ettinger
Cryonics Institute
Immortalist Society
http://www.cryonics.org

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