Can you freeze your body and come back to life? - Shannon N. Tessier

譯者: Camila Lin 審譯者: 穎君 紀

On January 12th, 1967, James Bedford passed away.

1967 年 1 月 12 號， 詹姆斯·貝德福德去世了。

But— he had a plan to cheat death.

但是，他想出了欺騙死神的方法。

Bedford was the first person to be cryogenically frozen.

貝德福德是史上第一個 被人體冷凍技術保存的人。

This process promised to preserve his body until a theoretical future

人體冷凍技術將保存他的身體，

直到人類已能治療所有疾病， 且能讓人死而復生的未來。

when humanity could cure any illness, and essentially, reverse death.

This is the dream of cryonics.

這就是人體冷凍技術的願景。

But here’s the catch: to revive people in the future,

但這裡有個弔詭之處： 為了讓人們在未來復活，

we need to properly preserve them in the present.

我們現在就必須好好保存他們的身體。

So, is it currently possible to freeze a human,

我們現在真的能把人冰起來，

preserve them indefinitely, and then safely thaw them out?

長期保存人類肉體， 之後再安全地解凍它們嗎？

To understand the hurdles of human cryopreservation,

為了瞭解人體冷凍技術面臨的障礙，

we need to leave the theoretical realm of cryonics,

我們必須跳脫人體冷凍技術的理論，

and turn to the scientific field of cryobiology.

轉而來研究低溫生物學這門科學。

This discipline studies the effects of low temperatures

這個學科研究低溫 對各種生物系統的影響，

on various living systems,

and it is true that decreasing an organism’s temperature

而降低生物的溫度，

also decreases its cellular function.

的確也能降低細胞活性。

For example, at temperatures below -130 degrees Celsius,

例如，在零下 130 度時，

human cellular activity grinds to a halt.

人體細胞會逐漸停止活動。

So if you could bring an entire human body below that temperature,

所以，如果能把人體保存在這種低溫，

theoretically you could preserve it indefinitely.

理論上來說，人體就能永遠完好無損。

The hard part is doing this without damaging the body.

困難在於如何在不損害人體的情況下達成。

For example, let's try to freeze a single red blood cell.

例如，我們來試著冷凍一顆紅血球。

It typically sits at a temperature of 37 degrees Celsius

紅血球一般處於 37 度的環境中，

in a solution of water and substances known as chemical solutes,

泡在水和化學溶質組成的溶液裡，

which dissolve under certain conditions.

這些化學溶質在特定條件下會溶解。

But once the temperature drops below freezing,

然而，一旦溫度降到零度以下，

water outside and inside the cell hardens into damaging ice crystals.

細胞內外的水分就會凝結硬化， 變成具破壞性的冰晶。

Without the correct concentration of water,

而這時水分的濃度也會改變，

the chemical solutes are unable to dissolve.

化學溶質就無法正常溶解。

And as the water freezes, they become increasingly concentrated

而且，水一旦結凍， 水分子就會越來越集中，

in a destructive process known as osmotic shock.

這種具破壞性的變化， 稱為「滲透壓休克」

Without any intervention,

如果沒有任何外力干預，

these factors are guaranteed to destroy our red blood cell

這些變化就會在溫度降到負 130 度之前，破壞這顆紅血球。

before it reaches -130 degrees.

Not all cells are this fragile,

不是每種細胞都這麼脆弱，

and many animals have evolved to survive extreme conditions.

也有許多動物進化到 能在極端環境中生存。

Some cold-tolerant fish synthesize antifreeze proteins

有些耐寒的魚能合成抗凍蛋白，

to prevent ice formation at sub-zero temperatures.

避免血液在零度以下的環境中結冰。

And freeze-tolerant frogs use protective agents to survive

耐寒的青蛙則依靠抗冷凍物質，

讓牠們在體內七成的水 都已結冰時也能生存。

when up to 70% of their body water is trapped as ice.

It's unlikely that any one creature holds the secret to human cryopreservation.

雖然這些生物不太可能為我們 解開人類冷凍技術的秘密，

But by researching these adaptations,

但研究這些適應寒冷的方法，

scientists have developed remarkable preservation technologies,

也讓科學家發展出了不起的保存技術，

some of which are already employed in medicine.

有些技術也已經投入臨床實作。

However, researchers are still trying to improve cryopreservation technology

但是，研究者們 仍努力改良冷凍保存技術，

to better manage the ice problem.

以更有效解決結冰問題。

Many cryobiologists are trying to solve this issue

很多低溫生物學家試著以

with an approach called vitrification.

「玻璃化冷凍」解決這一問題。

This technique uses chemicals known as cryoprotectant agents (CPA)

這種技術使用稱為 「冷凍保護劑」的化學物質，

to prevent ice from forming.

來避免結冰。

Some of these have been adapted from compounds in nature,

有些冷凍保護劑是自然形成的化合物，

while others have been designed to take advantage of cryobiology’s

有些則是依照低溫生物學的 重要理論特別合成。

guiding principles.

But in practice,

但實際上，

these chemicals allow researchers to store living systems

科學家能用這些 化學物質來保存生命系統，

in a glassy state with reduced molecular activity and no damaging ice.

讓它們維持在玻璃化狀態， 降低細胞活性，也避免水分子結凍。

Vitrification is ideal for cryonics,

玻璃化冷凍技術 是人體冷凍的理想方法，

and would help preserve organs and other tissues for medical procedures.

也能保存器官與其他組織， 讓解凍後的身體較好處理。

But it’s incredibly difficult to achieve.

但要達到這個目標非常困難。

CPAs can be toxic in the high quantities required for large scale vitrification.

為了保存大質量的物體， 大量的冷凍保護劑可能會產生毒性。

And even with these chemicals,

而且就算有冷凍保護劑幫忙，

preventing ice formation requires rapid cooling

我們仍需要迅速冷凍物體， 才能預防結冰，

that lowers temperatures uniformly throughout the material.

而且過程中，要均勻地降低溫度。

That’s relatively easy when vitrifying single cells or small pieces of tissue.

冷凍一個細胞或一小片組織時還不難，

But as the material becomes more complex and contains larger quantities of water,

但如果冷凍的物體更複雜， 含有更多水分，

staying ahead of ice formation gets challenging.

就越來越難在結冰之前完成冷凍。

And even if we could successfully vitrify complex living material,

而且就算我們能用玻璃化冷凍技術 成功冷凍複雜的生物體，

we'd only be halfway to using it.

挑戰也還沒結束。

Vitrified tissue also needs to be uniformly warmed

被玻璃化冷凍的組織需要均勻受熱，

to prevent the formation of ice, or worse, cracks.

才能預防結冰， 或是更糟糕的情況：破裂。

To date, researchers have been able to vitrify and partially recover

目前為止，研究者只成功 以玻璃化冷凍技術冷凍和解凍

small structures like blood vessels, heart valves, and corneas.

血管、心臟瓣膜和角膜這種小結構。

But none of these are anywhere near the size and complexity

但這些人體結構的尺寸和複雜性，

of a whole human being.

根本無法和完整的人體相比。

So if it’s not currently possible to cryopreserve a person,

所以，如果現在還 無法成功低溫冷凍人體，

what does this mean for Bedford and his frozen peers?

那貝德福德和其他 接受冷凍的人，又會如何呢？

The sad truth is that current cryonic preservation techniques

令人難過的現實是， 現在的人體冷凍技術，

only offer their patients false hope.

只能帶給病患虛假的希望。

As practiced, they’re both unscientific and deeply destructive,

實際上，現在的人體冷凍 既不科學，還具有毀滅性，

irreparably damaging the body’s cells, tissues, and organs.

會在身體細胞、組織和器官上， 留下不可逆的傷害。

Some devotees might argue that, like death and disease,

有些志願者認為， 這種傷害就像死亡和疾病，

this damage may be reversible one day.

或許有天也能靠技術逆轉，

Even if scientists could revive people through cryonic preservation,

但就算科學家真的能透過 人體冷凍讓人類死而復生，

there’s a whole suite of ethical, legal, and social implications

也會在道德、法律和社會等層面 產生一連串影響，

which cast doubts on the technology’s overall benefits.

讓大眾懷疑科學帶來的總體福祉。

But for now, the dream of cryonics is still on ice.

所以現在，人體冷凍的夢想 也被暫時擱置。