经济学人下载:诺贝尔生理学奖 再生医学界的大好人

Science and technology
科学技术

The 2012 Nobel prizes
诺贝尔生理学奖

Good eggs
再生医学界的大好人

THIS year's Nobel physiology prize goes to Sir John Gurdon and Shinya Yamanaka for a crucial discovery in stem-cell science?—how to make what are known as pluripotent stem cells from ordinary body cells.
今年的诺贝尔生理学奖颁给了约翰格登爵士和山中伸弥，来表彰他们在干细胞领域的关键发现-那就是如何利用普通的体细胞来合成多功能干细胞。

What the citation does not say is that this work also allows clones to be made from adult animals, potentially including people.
诺贝尔颁奖典礼上的褒奖词没有指出的是，这项成果使得成年动物 的克隆成为可能，也有可能可以克隆人类。

A stem cell is one that can differentiate into daughter cells specialised for particular functions, and all the cells in a body are thus derived from stem cells.
干细胞是一种可以分化成姐妹细胞的物质，而姐妹细胞则担当某种特定的功能 ，体内的所有细胞都是来源于干细胞的。

That includes the stem cells themselves, which derive from ur stem cells found in embryos.
而干细胞则是来自胚胎中的ur干细胞。

These embryonic stem cells are the pluripotent cells, meaning they can turn into many other sorts of cell.
这些胚胎干细胞就是多功能干细胞，他们可以分化成很多其他种类的细胞。

Pluripotent embryonic stem cells are of great value to researchers but, if the embryos they came from were human, their use is controversial.
多功能胚胎干细胞对于研究者来讲弥足珍贵，但是如果这些胚胎来自于人类，那这些干细胞的使用就有争议了。

Also, if such cells are ever to play a useful role in medicine, then they will need to be available in bulk—and ideally in a form whose DNA matches that of the recipient.
而且，这些细胞在医药方面扮演着如何重要角色， 那么 我们就大量需要这些干细胞了—在理想的情况下，这些干细胞的DNA和接受者的DNA相匹配。

Sir John and Dr Yamanaka have both conducted work that should help make this possible.
格登爵士和山中博士的研究就是来推动这一试想实现的可能性。

Sir John's prizewinning study, published half a century ago, in 1962, when he was at Oxford University, was to transplant the nuclei of cells from adults of a frog called Xenopus laevis into enucleated eggs of that species.
格登爵士的获奖研究发表于半个世纪前的1962年，当时他正在牛津大学读书，打算将一只成年非洲爪蟾的细胞核移植到同类的无核卵子中。

The eggs in question then developed into healthy adults.
这些卵子随后发育成健康的非洲爪蛙。

This showed that DNA is not altered during embryonic development, at least in Xenopus.
这表明DNA在胚胎发育的过程中并未变异，只是在非洲爪蛙的身上没有发生变异。

It thus suggested it might be possible to get an entire adult cell to perform a similar trick, without involving an egg at all.
这表明很有可能在得到一个成年完整细胞的情况下，通过同样的试验，但是不用卵子。

That was what Dr Yamanaka did.
而后者就是由山中博士完成的。

He and his colleagues at Kyoto University managed to activate four crucial genes in adult mouse cells.
在日本京都大学，他和他的同事成功激活了四个成年老鼠细胞中的关键基因。

These genes each encode a protein of a type known as a transcription factor, which controls the expression of DNA.
这些基因每个都可以表达生成一种蛋白质，转录因子，控制DNA的表达。

Together, they trick the cell in question into thinking it is part of an embryo.
和他的同事一起，他们将试验细胞看成胚胎的一部分。

In the first experiment, conducted in 2005, Dr Yamanaka did not get complete mice, but he did turn the adult cells into pluripotent stem cells. Subsequent work by his group and others then produced embryos which, if transplanted into the womb of a female mouse, will go all the way to adulthood.
第一个试验是2005年完成的，山中博士的细胞没有发育成完整的老鼠，但是博士确实将成年细胞转化成了多功能胚胎干细胞。他的科研小组随后生成了这种胚胎，如果将该胚胎植入一只雌性老鼠的子宫内，它就会发育成老鼠。

Finally, in 2007, Dr Yamanaka managed to switch on the same four genes in adult human cells, and thus generated pluripotent human stem cells.
最后，于2007年，山中博士成功转变了成年人体细胞中的同四种基因，而后生成了多功能人体干细胞。

In principle, that opens the door to human cloning, though no one has tried this in practice—and in most countries such an experiment would be illegal.
理论上，这一研究开启了人类克隆的大门，尽管还没有人曾付诸实施-大多数国家，这种试验都是非法的。

It also opens the door, though, to bespoke tissue repair as it would allow cells of whatever type were desired to be grown from, say, a few skin cells and then transplanted back into the donor without risking an adverse reaction from his immune system.
这一研究也开启了订制组织修复的大门，因为可以将任何种类的细胞转化成别的细胞，比如，一些皮肤细胞被移植回到捐献者的体内，而不用担心会对捐献者的免疫系统造成不良影响。

How well that would work in practice remains to be seen.
在实践中，这项研究能走多远，我们拭目以待。

But if it works well then Sir John and Dr Yamanaka may turn out to have been the pioneers of a whole, new field: regenerative medicine.
但是如果成功的话，格登爵士和山中博士就成为一项全新领域的先驱了，那就是再生医学。