X-Message-Number: 4204
From:  (Brian Wowk)
Newsgroups: sci.cryonics
Subject: Re: Cyroprotective Proteins ?
Date: 13 Apr 1995 17:24:35 GMT
Message-ID: <3mjmoj$>
References: <3mhbdg$>

In <3mhbdg$>  (Jim0123) writes:

>Hate to interrupt the decidedly metaphysical trend of this group
>(suggesting perhaps a deficit of *real* progress in cyronics?) but

	Sad, but true.	

>perhaps someone knows if there have been any credible experiments
>involving some of the cyroprotective proteins and polysaccarides
>found in arctic fishes and some small animals which hibernate thru
>the winters essentially frozen ? 

	The basic problem is that hibernation
and high-sub-zero freezing involve issues much more complicated
than just ice crystals.  Biochemical reactions require a minimum
activation energy to proceed.  As organisms like us are cooled
below normal body temperature, critical reaction pathways one-by-
one shut off.  The reactions that remain create metabolic imbalances
that are unsustainable.  The longest time a non-hibernating
mammal (dog) has been maintained in a state of hypothermic arrest
and still recovered is 6 hours at 4 degC.  It is very difficult
to viably maintain non-hibernating mammals near freezing for
longer than this because their basic metabolism has not evolved
to function at these temperatures.  Ice crystals have nothing
to do with it. 

	The basic approach used by cryonics and transplant
medicine for hypothermic storage is blood substitution.  Blood
is replaced by a special perfusate that is designed to 
minimize metabolic imbalances at low temperatures.  The body
or organ is then transported in circulatory arrest on ice to
where it is needed.  The tolerance of different organs to this
process varies greatly.  Kidneys and livers are good for
about 72 hours, hearts maybe 10 hours, and skeletal muscle
even less time.  It is not unheard of for cryonics patients
who are transported long distances on ice to cryonics facilities
to arrive with muscles in rigor mortis, but kidneys that are still
transplant-viable.  As you can see, "hibernation" for non-hibernators
is a complex problem.  It is not likely to be solved by anything
less than a major overhaul of our basic metabolism. 

	The only practical form of biostasis today is low-sub-zero
storage (i.e. bring everything to a complete stop).  Doing this
without cell damage is not as difficult as your post suggests.
Certain mixtures of cryoprotectants can be made to vitrify 
(forming a non-injurious glass) instead of freezing (forming ice
crystals).  This process has been nearly perfected for kidneys,
and the next target organ will be the brain.  I think there is
a good chance that reversible cryopreservation of the human brain
will be achieved within the next ten years.  In other words, we
will have the ability to store and recover brains in a viable
condition with CURRENT not future technology.

	Regarding your comments about cost, you should be aware
that most people who make cryonics arrangments are middle-class,
and pay for it with life insurance.  Storing at higher temperatures
(like -130'C... the highest temperature at which all chemistry stops)
is more complex than simple -196'C liquid nitrogen storage, and
only reduces costs if your storage facility is reasonably large.
We are not quite at the point yet where -130'C storage can be
justified on a cost-savings basis.

	I might add that *patient numbers* (economies of scale) will
be the single most overriding factor in bringing down storage
costs in years to come.  The more patients you have, the larger your
volume to surface area ratio will be, which is what really drives
storage costs.  Storage in Antartica (even if it was cold enough)
will never be economically justifiable because the transport costs
would exceed the capital cost of perpetual care in
any secure cryonics facility with a reasonable economy of scale.

	Two trends will be apparent in cryonics in years to come.
1) Storage costs will come down due to economies of scale.
2) Up-front costs will go up due to more sophisticated procedures,
like vitrification.  For some procedures, like neuropreservation,
we are already in a situation where up-front costs make up about
70% of the total cost.  Even dramatic reductions in storage costs
will therefore do little to improve the affordability of cryonics.
What we may eventually see as a cheap alternative would be low-tech
up-front procedures combined with inexpensive mass storage.  But
would the FDA permit it?   

Brian Wowk
Director, CryoCare Foundation


Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=4204