X-Message-Number: 32812
Date: Wed, 01 Sep 2010 07:34:49 -0400
From: 
Subject: Re: a proposal to stimulate cryonics research

Nearly three weeks ago Douglas Skrecky posted
his message "a proposal to stimulate cryonics research":

http://www.cryonet.org/cgi-bin/dsp.cgi?msg=32767

to which this is my belated reply.

  The focus of Doug's message on cryoprotectant
toxicity shows that his heart and mind are in
the right place, so I hope that my acknowledgment
of this fact is not lost because I have some
criticisms of the details of his message.
In particular, I disagree with his claim that:

"By pulling out all the stops, expense be damned,
and actually using these less toxic but pricey cryoprotective
agents such as ectoin, DESO, and KF7G; fully reversible
liquid nitrogen cryopreservation of entire animals is
IMHO quite possible right now."

  KF7G is an anti-freeze flavonol glycoside, comparable
to anti-freeze proteins and ice blockers in its
mechanism of action. Although the 9oC freezing-point
depression of KF7G is more impressive than that of
any other ice-blocker, KF7G is not a cryoprotectant
and can do no more than assist cryoprotectants a bit
in achieving and maintaining vitrification.

Doug cites a single paper showing the effectiveness
of DESO as a cryoprotectant on a single organism,
the bacterium Escherichia coli. Although 85% viability
for 45% DESO concentration is impressive, it is not
the same as 100% viability and E. coli is not a
mammalian cell. The relative toxicities of the various
cryoprotectants varies remarkably with cell type:

http://www.benbest.com/cryonics/viable.html#toxicity

The University of Michigan does not have or
have access to the paper you cited for ectoin, although
I similarly note that 72% survival of a single
cell type is not the same as 100% viability for
all cell types.

As I have been saying for years, the greatest
breakthrough for cryonics would be the
elimination of cryoprotectant toxicity, and
the focus on research should be on understanding
what cryoprotectant toxicity is. If we do not
understand the mechanisms of cryoprotectant
toxicity, we are poorly equipped to eliminate it.
Current understanding of the mechanisms of
cryoprotectant toxicity is sketchy, in my opinion:

http://www.benbest.com/cryonics/viable.html#mechanisms

If we could have a Manhatten project for studying
cryoprotectant toxicity we could have a significant
chance of dramatically advancing cryonics. But this
requires lots of money and lots of recognition of
the importance of this problem.

Many cryobiologists have been aware for
many years that cryoprotectant toxicity is
"the central problem blocking successful
cryopreservation by vitification":

http://www.ncbi.nlm.nih.gov/pubmed/3595164

but in cryobiology, as in cryonics, the money
and commitment have not been in place to solve
what is the most important problem. Nor has there
been sufficient understanding that it is the most
important problem. I appreciate, Doug, that you
have this recognition.

          -- Ben Best

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