TRANS TIME Cryonics Intro -- Hibernation, Hypthermia, and Cryobiology

Hibernation, Hypothermia,
and Cryobiology

(Under Construction)

Hibernation is nature's way of saying "time out". When the ground is covered with ice and snow, and food is hard to find, certain small animals will burrow into protected hiding places, curl up into little bundles, and let their body temperatures fall to near the ice-point. As they grow colder, their body functions slow, their heartbeats are less frequent, their breathing almost stops. Since they use much less energy, their food requirements plunge. What might normally be a few days supply, might last for weeks, or even months.

Some animals, such as arctic insects, allow their bodies to freeze solid over the winter. They produce substances which protect their cells against the formation of ice. Many of these substances are sugar-like compounds. A common one is glycerol, a simple chemical containing three carbon atoms. Glycerol is a "cryoprotectant". It is a molecule which protects living tissue from freezing damage. Glycerol was found many years ago to permit human cells, such as those in sperm and blood, to survive freezing to very low temperatures and to be stored there for long periods of time. Today, such freezing techniques can be used to help childless couples, and to save lives in the emergency room.

Recently, several kinds of frogs were discovered which can tolerate freezing below the ice-point. During the winter, these animals, which inhabit the leaf cover of forests in certain chilly regions of the northern United States, and Canada, produce glycerol, or other cryoprotective agents. They then allow between one-third to one-half of their body water to become ice.

The water in their tissues, external to their cells, freezes. This water, in their blood, lymph and other body fluids, is thus rigid and immobilized. The metabolism of their cells, thought to remain unfrozen, becomes very slow. The heart does not beat. The blood does not circulate. There is no breathing. The frogs are in true suspended animation. They do not move.

These frogs can tolerate months with their bodies frozen rock-solid. In the Spring they warm, their bodies thaw, and they come back to life.

During the 1950's a group of English scientists under the direction of Dr. Audrey Smith, discovered that hamsters could be partially frozen for brief periods of time and to temperatures slightly below the ice-point, and then revived. The bodies of these hamsters, unlike those of freeze-tolerant frogs, cannot make large quantities of cryoprotectants. Smith and her colleagues found that without such chemicals, the hamsters, unlike the frogs described above, could not revive if frozen for more than a very few hours or chilled more than a degree or two below freezing.

They tried injecting cryoprotectants into the blood of these hamsters, and they added them to their drinking water. Try as they might, they failed to get enough cryoprotectant into the animals to allow them to freeze and thaw safely, or, if too much was introduced, the hamsters would die. Ultimately they gave up, Smith writing that some way must be found to administer cryoprotectants if such animals were to be frozen and thawed successfully.

In the years that followed, techniques of cardio-pulmonary by-pass were developed which allowed blood to be circulated and oxygenated without the activity of the heart or lungs. Scientists and physicians began to experiment with lowering body temperatures and diluting the blood with blood-substitutes. In the late 1960's and early 1970's, a surgeon named Gerald Klebanoff, and his team at the Lackland Air Force Base near San Antonio, Texas, succeeded in lowering the body temperature of dogs close to the ice-point, and replacing their blood with solutions which could be circulated for up to eight hours. Some of his dogs recovered and survived for more than a year before they were sacrificed and studied.

We became interested in applying the techniques developed for cardio-pulmonary by-pass, and ice-cold blood-substitution, to hamsters. We want to deliver cryoprotectants to the tissues of their body, and then try to revive them following freezing and storage under the conditions from which frogs routinely recover in nature. In this way we are hoping to use the progress made in large animal and human surgery to complete the efforts initiated by Smith and her co-workers more than three decades ago.

In order to pump fluids in and out of the hamster bloodstream, we developed a tiny hollow tube made from a teflon-like material, with a sharpened steel wire inserted down the middle. This "micro-cannula" enables us, using microsurgical techniques under a stereo-microscope, to intubate the hamster's tiny carotid artery, and pump blood substitutes into the animal's circulatory system. Using a small, commercially-available medical catheter placed in the jugular vein, we complete the circuit and can pump fluids into the animal, as well as collect and study what flows out.

The above methods have allowed us to replace the blood of chilled hamsters with a variety of blood-substitutes, observe the efforts of these blood-substitutes on the animals, and then replace the blood substitutes with blood harvested from other animals. Once transfused with whole blood, the hamsters can be warmed up and revived.

Initially we used the same kinds of procedures for chilling our hamsters to the ice-point as did Smith and her collaborators. Now, however, we employ modern anesthetics such as ketamine not available at the time.

During the last three years, we have tested many different solutions and procedures for reviving blood-substituted hamsters. We are learning what blood-substitutes promote survival in the bloodless state, and how best to introduce them and remove them. We have even briefly frozen a few hamsters whose body temperatures were as low as -11^oC, and whose circulations were perfused with a blood-substitute containing glycerol. In some of these hamsters, the heart began to beat (as indicated by the EKG) after thawing. Having only begun to explore this possibility, we have not as yet been able to fully revive such animals. However, we expect to pursue this goal more vigorously in the future.

We have, however, been able to revive hamsters after they have been perfused with concentrations of blood-substitutes containing the same amount of glycerol as found in frogs which revive after partial freezing. We are thus hopeful that under the conditions of our experiments, these cryoprotectants may be tolerated by the animal.

We wanted to know whether the techniques which we were developing in hamsters could be used on larger animals, or even people. Such techniques could be of great value during surgery, in the treatment of presently inoperable cancer, in harvesting organs from multi-organ transplant donors, and during the implantation of prosthetic devices such as artificial hearts. We therefore initiated a small series of experiments on dogs in order to test the applicability of what we learned on hamsters to larger, non-hibernating animals.

The dogs we studied were given anesthetics, cooled in ice-baths, instrumented with recording devices and surgically prepared for cardio-pulmonary by-pass. Their temperatures were lowered to 20^oC and their circulating blood was replaced with the same blood-substitute developed during our hamster experiments. Their body temperatures were dropped to 3^oC, their circulation was then arrested; the roller pumps of the by-pass circuit were turned off for 15 minutes.

After that time, circulation was begun. The animals were rewarmed, and the blood substitute was replaced by the animals' own blood which had been refrigerated during the procedure, and with a few pints which had been previously collected from other dogs.

After three preliminary experiments, we attempted this procedure on an animal which was to be maintained for an extended period of time. It worked ) the dog, now named "Miles" after the Woody Allen character in "Sleeper" who awakes from cryonic suspension two hundred years after a botched appendix operation ) is alive and perfectly healthy six months following more than one hour of near-bloodless cold.

This success has encouraged us to plan similar experiments in monkeys. If they succeed, then comprehensive studies of ice-cold blood substitution should be undertaken with the goal of perfecting related procedures in human surgery.

Ice-cold bloodless surgery has a great potential, as it may make possible long and complicated procedures which may not be performed with the heart and brain operative, and reduce the risks from massive blood loss and shock. Since a patient's own blood could be removed and stored during the surgery, this can help our dwindling blood supply, and prevent transfusion-based infections.

Ultimately, we hope to develop techniques to freeze patients below the ice-point, much as overwintering frogs protect themselves against the cold. This will be of importance in protecting the tissues of multi-organ transplant donors, in allowing patients needing transplants to survive until vital organs can be found for them, and for maintaining astronauts after life-threatening accidents or who become seriously ill during space exploration.

Recent advances in the ultra-low temperature preservation of vital organs through techniques such as vitrification suggest the possibility of applying ice-cold total body washout techniques to reversible long-term cryogenic storage of the terminally ill. This may be the best way to deal with victims such as those with Alzheimer's Disease, or with presently incurable and painful cancer, whose continued survival only results in further deterioration and an increased burden of personal, social and economic pain. A reversible cryonics suspension technique would allow such people to be revived when a cure for their condition was available.

[Note: portions of the foregoing were excerpted from an abstract titled "Ice-Cold Bloodless Dogs Revived Using Protocol Developed In Hamsters," originally presented by Paul Segall, Ph.D., Hal Sternberg, Ph.D., and Harold Waitz, Ph.D. of TRANS TIME, INC. at the March 29-April 3, 1987 Meeting of FASEB Science Editor.]

...

(From CryoNet -- To be added to the above with other amplifications.)

BRING 'EM BACK ALIVE!

BioTime, Inc. has just issued the following press release:

Berkeley, California, May 29 1992.

BioTime Inc. has, for the first time, successfully revived a baboon following a procedure in which the animal's deep body temperature was lowered to near-freezing and its blood was replaced with BioTime's patent-pending blood-substitute solution. The animal was anesthetized, immersed in ice and cooled to below 2 degrees Celsius, using the BioTime solution with cardiopulmonary bypass procedures. After being bloodless and below10 degrees Centigrade for 55 minutes, the animal was rewarmed and revived. The baboon is presently under study by BioTime scientists to determine any long-term physical effects. The company intends to conduct further experiments on primates,using its blood-substitute solutions.

---------- Further information from Art Quaife (of Trans Time, not BioTime):

Over the past five years, we have had a number of similar successes with dogs, including recovery from four and one half hours of cold washout. Now we are scaling up one step closer to humans. Four more baboon experiments are planned over the next few months, in which we will attempt to extend the washout time.The principal experimenters were Dr. Paul Segall, Dr. Hal Sternberg, Dr. Harold Waitz, and Judy Segall. All are officers or advisors of Trans Time, Inc. Trans Time has the right to useBioTime's solutions for cryonics purposes, and indeed these are the solutions we use in the cryonic suspension of our patients. The experimenters were ably assisted by the expert staff of a private research laboratory, whose personnel also assist Trans Time in cryonic suspensions. Trans Time owns shares of BioTime that are currently trading on the NASDAQ for more than $340,000. Of course we hope that this exciting development will increase the value of BioTime. Trans Time's own offering of stock closes on June 30. [ ... This note is not an offer to sell nor a solicitation of an offer to buy Trans Time securities. - KQB ] Th[at] Offering is made only through the Offering Notice, and the CRYONETdoes not endorse or promote any investments.

How cold is cold enough? (by Hugh Hixon)

What kind of damage is done? (Cryobiology/Neurobiology)

Cryopreservation of the Mammalian Kidney

Cryobiology: The Study of Life and Death at Low Temperatures

Here's the official site for Cryobiology, International Journal of Low Temperature Biology and Medicine (The Official Journal of the Society for Cryobiology), and here is the online archive of Cryobiology in the International Digital Electronic Access Library (which will log you onto their system as a guest).

Human Embryo Cryopreservation now occurs routinely.

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