X-Message-Number: 15325
From: 
Date: Thu, 11 Jan 2001 22:47:09 EST
Subject: INC announcement

Although I am not on the mailing list, I have received a copy of a message 
from Paul Wakfer of the INC, which includes a progress report on the (rat) 
hippocampal slice cryopreservation project. It does not yet appear to be on 
the INC web site.

The gist of it is that, since the Asilomar conference, new CPAs have been 
tried and viability by the potassium/sodium criterion is now up from 53% to 
66%, which is the same as for vitrified/rewarmed rabbit kidneys by 21CM.

That's good news--congratulations to the people involved.

At the same time, let me note a couple of qualifiers. As usual, this is in 
part my effort to make sure I understand the message. All of us former 
teachers know that a very good way to check whether you understand something, 
or to learn what needs clarification, is to try to explain it to someone else.

At one point the progress report, signed by the director of research, says 
that the thrust of the experiments [since Asilomar] has been toward "more 
sophisticated" vitrification solutions, and that some changes in treatment 
and evaluation procedures were needed,slowing progress. At another point it 
says that the researchers expect in January to use an improved vitrification 
solution, and in February still another. This seems slightly confusing. 

The report contains some cautions. One is that non-penetrating 
cryoprotectants, requiring time to diffuse into the slices, necessitated 
using the highest concentrations of cryoprotectant for longer times in order 
for vitrification to occur. Since this was done with thin slices, it seems 
clear that the problem with whole rat brains, let alone human brains, would 
be compounded. 

Another caution is that, although the 66% recovery is believed to apply to 
every cell and is not just an average number, longer culture times, up to 8 
hours of incubation, did not improve the K/Na assay. The workers had hoped 
that cells 66% functional would, over time, repair themselves and recover 
fully, but that has not yet been observed.

The lead researcher does emphasize that the combination of "presumably" 
ending ice damage and also reducing toxicity represents an enormous 
improvement over previous procedures (with brain slices). Microscopy studies 
are to follow, and everyone hopes for the best possible outcome.

When the results are in and the total situation clarified, then, as many 
times noted, our intention at CI is to make any useful results available to 
our members in the most efficient and expeditious way we can manage.

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








Intact rat brains, however, take up cryoprotective agents (CPAs, 
cryoprotectants) poorly.  A brain tissue slice model will eliminate any 
contribution of the blood brain barrier to this failure of CPA uptake. 

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