X-Message-Number: 2614
Newsgroups: sci.cryonics
From:  (kevin.q.brown)
Subject: Re: Problem with Cryonics
Date: Wed, 16 Feb 1994 23:36:05 GMT
Message-ID: <>
References: <>

In article <>,  writes:
>  The damage occurs because of a common property of water: It expands
>  when it freezes. Basically, the water in the cells freezes and ruptures
>  the cell wall, badly damaging them. It is conceivable that sometime in
>  the future people will be able to repair the damage.

The visual image I get from your description is that a cell is basically
a bag of water and that when the cell and the water it contains
freeze, the water expands, bursting apart the cell.  Surprisingly,
that's not how it works, at least when freezing is done slowly.
As I recall from presentations I saw a few years ago, the chemistry
of the cell (ph, etc.) changes as it cools and the cellular
metabolism (ion pumps, etc.) slows down.  One result of these
chemical and metabolic changes is that the cell dehydrates;
water leaves the cell, leaving it with a higher concentration of
the various chemicals inside.  (This chemical change can result in
some damage to the cell, but I don't recall if that is one of
the major concerns.)  When the water finally freezes, the ice
crystals form almost entirely *outside* the cell, not inside it.
The expanding ice crystals do indeed cause mechanical damage to
the surrounding cells, puncturing or severing pieces, but it's not
like the "exploding cell" scenario above.  By the way, the
damage does tend to produce "clean cuts", not just random
jumbling or stirring of cellular debris, which is good news.
That will simplify reconstruction of the cells during revival
of the patient.
                               Kevin Q. Brown
PS: If the cell gets vitrified, rather than just frozen, then
    the water will not freeze to ice crystals, but instead will
    produce a glass.  That is largely why vitrification is an
    important topic for cryonics.

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