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. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=2614