评论
打印
Here at SciShow, we recently learned a fun fact: you can donate over half your liver to someone who needs a transplant, and the tissue will grow back within a year.
最近我们了解到了一个有趣的事实：你可以给需要移植的病人捐赠大半肝脏，而组织也将在一年内重新长出。
So then we got super curious: could you just keep cutting chunks off, donating them, and regrowing your liver, kind of like donating blood, except it's an organ?
所以我们超级好奇：能不能不断地捐赠肝脏，不断让自己的肝脏重新生长，就像献血一样，只不过捐赠的是器官呢？
Turns out, the answer is no. Which is kind of a bummer, because that would've been cool.
事实是，不可以。答案有些失望，因为能不断捐赠的话很酷。
But the reason why is really interesting — it's because of how the liver cells get replaced. Liver regrowth in humans is pretty amazing.
但是其中原因很有趣—这是由于肝细胞被替换的方式。人体肝脏重新生长相当惊奇。
In a study of 27 living liver donors, it only took about a month after donation for their liver function to return to normal,
对在世的27名肝脏捐赠者的研究中，他们的肝脏功能在捐赠仅一个月后就恢复了正常，
and less than a year for their liver to regrow its normal mass. And you could probably regrow your liver more than once.
不到一年时间里，他们的肝脏就重新生长成正常体积。并且肝脏可多次再生长。
In one study, a very unlucky rat had part of its liver removed again and again, and supposedly it grew back 12 times!
在一项研究中有一只非常不幸的老鼠，它的肝脏被一次又一次的摘掉，推测它的肝脏重新生长了12次！
That being said, rodent livers have a different structure than ours — so it might not work exactly the same in us.
话虽如此，但啮齿类动物的肝脏和人类肝脏结构不同—所以对人类而言可能行不通。
But even if it's possible to donate part of your liver more than once, transplant doctors probably wouldn't recommend it.
但是即使能够多次捐赠你的部分肝脏，移植手术医生或许也不会建议这么做。
First of all, even though it's pretty safe if you're under age 60 and healthy, it's a major surgery.
首先，虽然移植手术相当安全（如果你不到六十岁且身体健康），但这毕竟是个大手术。
And the bigger problem is: the regrown liver chunk likely wouldn't do any good.
最大的问题是：重新生长出来的肝脏部分起不到任何作用。
Because the liver regrows, but it technically doesn't regenerate. True regeneration occurs in some animals, like salamanders.
因为肝脏是重新长出来，技术上讲，肝脏是无法再生的。真正的再生只发生在一些动物身上，比如蝾螈。
If a salamander loses a leg, cells near the cut dedifferentiate. In other words, they revert to an earlier developmental state.
如果一只蝾螈断了一只腿，伤口附近的细胞会去分化。换句话说，它们会还原成了一种早期的发育状态。
They basically become the cells in an embryo that have no specific job, but they have the potential to turn into tons of cell types
从根本上讲是变成一个胚胎中的细胞，它们并没有特殊工作，但却有着转化成无数细胞类型的潜力
— from bone to skin to muscle — depending on what molecular signals they get.
—从骨头到皮肤再到肌肉—这取决于它们所获得的是什么分子信号。
Then they multiply, divide up into groups, and respecialize into all the cells that make up a leg.
然后它们开始繁殖、分化成不同组并重新特化所有构成腿的细胞。
It's essentially a redo of what happens as the salamander embryo develops, so the leg structure is the same, and scientists consider it regeneration. Good as new!
本质上来讲，这是蝾螈胚胎发育的重复，因此腿部结构也是一样的，科学家认为这是再生。恢复如新！
But this isn't what happens when part of your liver gets cut off.
但是人体肝脏切下来后，却不会如此。
Instead of all this dedifferentiation, what mostly happens is a variety of mature liver cells just multiply to make up for the loss.
和所有去分化不同，人体中主要发生的是—各种成熟的肝细胞仅靠繁殖来弥补损失。
The regrown tissue has some structure, but it doesn't replicate the exact layout of a fresh liver, from cell organization to the arrangement of blood vessels.
重新生长的组织有些结构，但是并不会复制新鲜肝脏的精密结构—从细胞组织到血管的配置。
So even though the regrown liver is fully functional, it's not true regeneration. Technically, what your liver does is called compensatory hyperplasia.
所以虽然重新生长的肝脏完全是功能性的，但这却不是真正意义上的再生。学术上讲，你肝脏所做的一切被称为代偿性增生。
This different structure would make it harder for transplant surgeons to safely remove a portion of a repeat-donor's liver.
这种不同的结构将使器官移植外科医生安全移除重复捐赠者的肝脏变得更加困难。
It'd also be harder to connect that regrown chunk to the transplant recipient's blood vessels, so they could actually use it.
要将重新生长的肝脏部分和移植受者的血管相连接使肝脏可用也更加困难。
So even though a liver donation can save someone's life, doing it more than once isn't a good idea for you or the person who needs the help.
所以虽然一个捐赠肝脏可以拯救别人的性命，但是多次捐赠对你和受助人都不好。
Thanks for watching this episode of SciShow!
感谢收看本期科学秀！
If you want to learn more about how weird the human body is, you can check out the video that inspired this question,
如果你想了解更多人体诡异之处，请观看我们的视频，
which is all about organs you could live without.
受该问题启发，视频中讲述了所有那些不必要的人体器官。
