Suspended Animation

Dreams of the Future?

One sure way, if you believe it will work, to see the future is to be frozen in a centuries’ long dream and be revived to see the wonders of a new era. At the moment the possibility only exists within the confines of science fiction, our bodies are no more capable of slowing down the activity of our cells than we are of stopping breathing for more than a few minutes, without causing ourselves serious damage. Yet there are creatures on our planet that are capable of putting themselves into a state of suspended animation; some creatures stay dormant like this for up to a decade, then emerge from the earth as if they had a quick afternoon nap. The different states some animals are able to achieve go by names such as quiescence, torpor and hibernation – all of which are a variety of suspended animation, a significant drop in energy production, or metabolism, and energy consumption, or cellular activity. Another factor in creatures in this state is that they are less susceptible to temperature extremes, oxygen deprivation and physical injury.

If humans were able to artificially perfect the conditions of suspended animation on organs for instance, it could drastically change the face of medicine for the better; where some transplant organs only last for a day, or even a few hours, it may be possible to keep them indefinitely. The process could also be used on car crash victims to reduce the amount of blood loss, head trauma and stave off tissue damage till treatment begins at the hospital.

Some tests at laboratories at the Fred Hutchinson Cancer Research Center in Seattle have shown that some animals can be induced into a state of hibernation; the remarkable thing is that the animals tested are not those that would normally hibernate. These experiments have raised hopes that suspended animation may one day become a science fact, not merely confined to actors in horizontal refrigerators flying through deep space to do battle with aliens. The scientists, who have succeeded in creating a state of suspended animation in animals and human tissue samples, believe it may be the case that many of Earth’s organisms possess a latent ability for suspended animation that dates back to our roots in the very first days of microbial life.

Furthermore, Ripley and her suspended animation tanks may not be as far from reality as one may think; in the real world animals that naturally go into a state of suspended animation do so under specific conditions, usually involving an environmental stressor that keeps them ‘suspended’ until the stressor is removed. Examples include seeds that stay in the ground for years, waiting for the correct environmental condition before they germinate; embryos of a species of brine shrimp (Artemia franciscana), known to most as sea monkeys, can survive for more than five years without water, oxygen or food – entering into a seed-like state known as quiescence in which their cellular activity is nigh on zero, on reintroduction to the right conditions in water, they resume their growth right through adulthood; all kinds of mammals that hibernate throughout the winter, waking only when the temperature rises, have metabolisms that slow to almost nothing, consuming hardly any energy at all and lowering their body temperatures to almost freezing.

These creatures’ ability to last for such a long period with little oxygen, which is achieved through extremely low energy production, is hugely different to the way a human body functions. Humans are totally dependent on their oxygen supply, deprived for only a few minutes the body’s tissue will deteriorate and die due to ischemic damage to cells. It is ischemia that is often the cause of death rather than the heart attack or stroke that a patient suffers from, because of the lack of blood flow not supplying the cells with oxygen. Having said this, some of the events on a molecular level during an ischemic event are as yet unknown; what is certain though is that a lack of oxygen causes the cells to literally run out of juice and stop, resulting in ischemic damage. It is for this reason that first aid’s primary goal is to resume blood flow and breathing when there is none, using CPR (cardiopulmonary resuscitation) and other contemporary methods – this being the only known strategy to fuel the oxygen-thirsty cells.

However, animals in a state of suspended animation seem almost immune to ischemia and its effects, which could suggest that humans may be the same if it were possible to induce the same suspended state. Scientists know that when blood flow stops oxygen never leaves the cells completely, there is always a residual amount that is sufficient for some kind of activity but not enough to prevent ischemia. It has been discovered that it may be advantageous to remove this small amount of oxygen so that there is none whatsoever, preventing any kind of activity, including cell decay. They believe that a special kind of substance that mimics oxygen on a cellular level, called a mimetic, that bonds to many of the same places as oxygen but does none of the same things chemically may be introduced to the body to achieve suspended animation.

Experiments have been carried out on animals that would never hibernate naturally, to see if cellular shutdown could be achieved safely and also if it were possible to protect tissue long enough to repair an injury. The late Peter Safar and his co-workers at the university of Pittsburgh worked for nearly twenty years with dogs to try and perfect the method of suspended animation. Safar’s group described their experiments last year. To create the suspended state, cardiac arrest was induced in each of 14 dogs, and then the blood was drained out of the animals' bodies while a cold saline solution was infused into them. Saline has a much lower capacity for carrying oxygen than blood, so this procedure dramatically reduces the amount of oxygen in the dogs' tissues. Afterward, the dogs were unconscious, did not breathe and had no heartbeat. Safar's team then separated the dogs into a control group of six animals and a second group of eight that would undergo surgical removal of their spleens, a nonessential organ. After 60 minutes in the suspended state, all the dogs were revived by reinfusion of blood. Seventy-two hours later the dogs were all still alive, and none of the control dogs showed any functional or neurological ill effects from their time in suspended animation. Four of the eight surgery dogs were also normal, although the other four displayed some neurological deficits.

The way that a dog’s body works and that of a human body is very similar, inducing many to get excited about the possibilities of suspended animation experiments in people – could hospital emergency rooms soon be using this technique?

Although it’s a big leap to start completely draining the blood from trauma patients, it may be useful to use the technique on donor organs that are blood-free already – sealing them in an airtight container and filling it with an oxygen replacing substance such as carbon monoxide, the organ would be re-oxygenated simply by the introduction of blood when it is transplanted into the recipient. Carbon monoxide could only be used in extracted organs though, if it is introduced to any organs with blood flowing through it tend to attach itself to red blood cells in the places where oxygen would normally reside, making it impractical to use on trauma victims. This is where an alternative oxygen mimetic would be useful.

Hydrogen sulfide has been used in warm-blooded animals with a great degree of success, the effects being that the animals were temporarily changed into cold-blooded animals – much the same as hibernating animals are naturally converted. Mice have been kept in this situation for 6 hours, then revived with no detectable negative effects after vigorous testing. It is believed that hydrogen sulfide is the way ahead to safely induce a state of suspended animation in creatures that do not normally hibernate, including humans – H2S is technically a poison, but it is also created naturally within the human body. It is even thought that H2S may play a hidden role in regulating cellular energy production in oxygen-breathing creatures. There are still many more tests to undertake and questions to answer before hydrogen sulfide is used to induce suspended animation in human beings – one of the biggest being whether or not humans are even capable of entering a state of suspended animation.

There are various cases around the world of people surviving for unprecedented lengths of time in an extremely low-oxygen environment after an accident, sometimes surviving several hours without any oxygen at all and fully reviving with all their mental faculties. A Norwegian backcountry skier was rescued after an accident that left her under ice-cold water for more than an hour. When the emergency crew found her, she was clinically dead—not breathing, without a heartbeat, and with a core body temperature of 14 degrees C (57 degrees Fahrenheit). Despite requiring nine hours of resuscitation, she has since made an "excellent" recovery, according to her doctors.

Another 32 cases of severe hypothermia in which core body temperatures ranged from 17 to 25 degrees C (63 to 77 degrees F) and many of the victims lacked vital signs when rescued were analyzed by Beat H. Walpoth of the University of Bern in Switzerland. He found that nearly half—15 patients—recovered from the trauma without any long-term impairment.

The question is though, what makes these people survive in these condition when so many others would die in exactly the same circumstances – once we can answer this question, suspended animation may become an everyday reality, we may even use it to reach distant stars?

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Suspended Animation by F. Gonzalez-Crussi