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

翻译人员: Shuhui Huang 校对人员: Yip Yan Yeung

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

1967 年 1 月 12 日， 詹姆斯·贝德福德 (James Bedford) 去世了。

But— he had a plan to cheat death.

然而—— 他有一个欺骗死神的计划。

Bedford was the first person to be cryogenically frozen.

贝德福德是史上 第一个被低温冷冻的人。

This process promised to preserve his body until a theoretical future

这个过程有望把他的身体 一直保存到将来

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

理论上人类能治愈任何疾病的时候， 并从根本上逆转死亡。

This is the dream of cryonics.

这是人体冷冻学的梦想。

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

但是问题在于， 为了让人们在未来复活，

we need to properly preserve them in the present.

我们现在就需要 妥善保存他们的身体。

So, is it currently possible to freeze a human,

所以把人冷冻起来， 无限期地保存，

preserve them indefinitely, and then safely thaw them out?

然后再安全地解冻， 是现在就可行的吗？

To understand the hurdles of human cryopreservation,

要了解人体冷冻保存的障碍，

we need to leave the theoretical realm of cryonics,

我们需要离开冷冻学的理论领域，

and turn to the scientific field of cryobiology.

而转向冷冻生物学的科学领域。

This discipline studies the effects of low temperatures

这个学科研究低温对不同生物体的影响，

on various living systems,

and it is true that decreasing an organism’s temperature

的确，降低一个生物的体温

also decreases its cellular function.

也会降低它的细胞功能。

For example, at temperatures below -130 degrees Celsius,

比如，当温度降低到 零下 130 摄氏度时，

human cellular activity grinds to a halt.

人类的细胞活动会慢慢停止。

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

所以如果你能把整个人体的温度 降低到这个数值以下，

theoretically you could preserve it indefinitely.

理论上是可以永久保存它的。

The hard part is doing this without damaging the body.

但难点在于， 不能伤害到身体。

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

打个比方，我们来试着 冷冻一个红细胞。

It typically sits at a temperature of 37 degrees Celsius

红细胞通常存活于 37 摄氏度、

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

包含水和化学溶质的溶液中，

which dissolve under certain conditions.

这些溶质会在特定条件下溶解。

But once the temperature drops below freezing,

可一旦温度降至冰点以下，

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

细胞里外的水都会冻结， 成为具有破坏性的冰晶。

Without the correct concentration of water,

没有足够的水，

the chemical solutes are unable to dissolve.

化学溶质就无法溶解。

And as the water freezes, they become increasingly concentrated

而当水结冰时， 这些溶质的浓度会逐渐升高，

in a destructive process known as osmotic shock.

这个破坏性过程 称为“渗透休克”。

Without any intervention,

如果没有任何干涉，

these factors are guaranteed to destroy our red blood cell

这些因素一定会 在达到零下 130 摄氏度之前，

before it reaches -130 degrees.

就摧毁我们的红细胞。

Not all cells are this fragile,

不是所有的细胞都这么脆弱，

and many animals have evolved to survive extreme conditions.

很多动物已经进化到 可以在极端条件下生存下来了。

Some cold-tolerant fish synthesize antifreeze proteins

一些耐寒的鱼在零下温度的时候，

to prevent ice formation at sub-zero temperatures.

会合成抗冻蛋白来防止体液结冰。

And freeze-tolerant frogs use protective agents to survive

而耐冻青蛙会在 身体中 70% 的体液都结冰之时，

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

通过分泌保护性介质而生存下去。

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

要说有哪种生物掌握着 人类冷冻学的密钥是不太可能的。

But by researching these adaptations,

但通过研究这些适应机制，

scientists have developed remarkable preservation technologies,

科学家们已经开发出了 卓越的保存技术，

some of which are already employed in medicine.

其中一些已经被应用在医药领域了。

However, researchers are still trying to improve cryopreservation technology

然而，为了解决结冰带来的问题，

研究者们还在尝试改进 冷冻保存技术。

to better manage the ice problem.

Many cryobiologists are trying to solve this issue

许多低温生物学家 正在尝试的一个解决方法，

with an approach called vitrification.

叫做玻璃化冷冻法。

This technique uses chemicals known as cryoprotectant agents (CPA)

这个技术使用一种被称为 冷冻保护剂 (CPA) 的化学物质

to prevent ice from forming.

来防止结冰。

Some of these have been adapted from compounds in nature,

其中一些 是从自然界中的化合物来的，

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

而另一些则是基于 低温生物学的指导原则而设计的。

guiding principles.

But in practice,

但在实际操作中，

these chemicals allow researchers to store living systems

这些化学物质使得研究者们 能把生物体储存在一个

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

分子活动减缓 且没有破坏性冰晶的玻璃态下。

Vitrification is ideal for cryonics,

玻璃化冷冻法 对于人体冷冻学是很理想的，

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

而且还有助于为手术 保存器官和其它身体组织。

But it’s incredibly difficult to achieve.

但它实现起来非常困难。

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

大规模玻璃化冷冻法 所需的大量冷冻保护剂可能会有毒。

And even with these chemicals,

即使有了足够的保护剂，

preventing ice formation requires rapid cooling

只有当降温过程是快速 而且均匀地发生时，

that lowers temperatures uniformly throughout the material.

才能防止冰晶产生。

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

在玻璃化单一细胞或是小块组织时 这是比较简单的。

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

然而当组织材料变得复杂， 且含水量增加时，

staying ahead of ice formation gets challenging.

在结冰前玻璃化就变得很难了。

And even if we could successfully vitrify complex living material,

就算我们能把活物成功玻璃化，

we'd only be halfway to using it.

那也只完成了一半。

Vitrified tissue also needs to be uniformly warmed

玻璃化了的组织 也需要被均匀地加热，

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

以防止产生冰晶， 更坏的情况是出现裂缝。

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

如今，研究者们已经能把类似血管、 心脏瓣膜和角膜这种小结构

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

成功地玻璃化并部分解冻了。

But none of these are anywhere near the size and complexity

但这些组织结构还是远远比不上

of a whole human being.

人体的尺寸和复杂度。

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

那么如果冷冻保存人体还不可行，

what does this mean for Bedford and his frozen peers?

这对贝德福德及其他冻起来的人们， 意味着什么呢？

The sad truth is that current cryonic preservation techniques

悲伤的事实就是 现今的低温保存技术

only offer their patients false hope.

只是给予病人们不切实际的奢望。

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

现在实行的操作， 是不科学也是很有害的，

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

会给身体的细胞、组织和器官 带来不可逆转的伤害。

Some devotees might argue that, like death and disease,

有些拥护者可能会说， 就像死亡和疾病，

this damage may be reversible one day.

这样的伤害 也许有一天就成为可逆的了。

Even if scientists could revive people through cryonic preservation,

可就算科学家能通过低温保存 让人们起死回生，

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

这也会带来一系列伦理、法律 和社会性的影响，

which cast doubts on the technology’s overall benefits.

这都让这项科技的总体收益 大打折扣。

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

而现在，人体冷冻的梦想 还被冰封着。