人类的皮肤细胞也能制造出婴儿了？

Nearly 40 years after the world was jolted by the birth of the first test-tube baby, a new revolution in reproductive technology is on the horizon — and it promises to be far more controversial than in vitro fertilization ever was.

世界上第一个试管婴儿震惊世界近40年之后，我们正面临着一项新的生殖技术革命——而它的前景比以往任何时候的体外受精都更具争议。

Within a decade or two, researchers say, scientists will likely be able to create a baby from human skin cells that have been coaxed to grow into eggs and sperm and then used to create embryos that can be implanted in a womb.

研究人员说，在10到20年内，科学家们或许就能够用人类皮肤细胞制造出婴儿了，这些细胞经诱使长成卵子和精子，然后用来产生胚胎，植入子宫。

The process, called in vitro gametogenesis, or IVG, so far has been used only in mice. But stem cell biologists say it is only a matter of time before the procedure could be used in human reproduction — opening up mind-boggling possibilities.

该技术名为体外配子法(in vitro gametogenesis，简称IVG)，迄今仅在小鼠身上做过实验。但干细胞生物学家说，IVG用于人类繁殖只是个时间问题——它开启的可能性将是惊人的。

With IVG, two men could have a baby that was biologically related to both of them, by using skin cells from one to make an egg that would be fertilized by sperm from the other. Women with fertility problems could have eggs made from their skin cells, rather than go through the lengthy and expensive process of stimulating their ovaries to retrieve their eggs.

使用IVG技术，两个男人也可以生育出生物学意义上的亲生孩子：把其中一个父亲的皮肤细胞制成卵子，再用另一个父亲的精子一起，培养成受精卵即可。而无法生育的女性也可以把皮肤细胞制成卵子，无需经历漫长的、昂贵的刺激卵巢取出卵子的过程。

“It gives me an unsettled feeling because we don’t know what this could lead to,” said Paul Knoepfler, a stem cell researcher at the University of California, Davis. “You can imagine one man providing both the eggs and the sperm, almost like cloning himself. You can imagine that eggs becoming so easily available would lead to designer babies.”

“这令人坐立不安，因为我们不知道这可能导致什么状况。”加州大学戴维斯分校干细胞研究员保罗·克内普夫勒(Paul Knoepfler)说。“你可以想象一个人同时提供卵子和精子，几乎就像克隆自己一样。你还可以想象，卵子变得如此容易获得，以至于可以生育出经过设计的婴儿。”

Some scientists are even talking about what they call the “Brad Pitt scenario” when someone retrieves a celebrity’s skin cells from a hotel bed or bathtub. Or a baby might have what one law professor called “multiplex” parents.

有些科学家甚至提到了“布拉德·皮特情景”(Brad Pitt scenario)的可能性：有人会从酒店的床上或浴缸里搜寻名人的皮肤细胞。或者一个婴儿可能会拥有法学教授所说的“多重”父母。

“There are groups out there that want to reproduce among themselves,” said Sonia Suter, a George Washington University law professor who began writing about IVG even before it had been achieved in mice. “You could have two pairs who would each create an embryo, and then take an egg from one embryo and sperm from the other, and create a baby with four parents.”

乔治华盛顿大学法学教授索尼娅·苏特(Sonia Suter)在IVG技术小鼠实验获得成功之前就在写这方面的文章了。她表示：“有些群体想在内部进行多重繁殖，你可以找到两对配偶，每对都形成一个胚胎，然后再从一个胚胎中取出卵子，从另一个胚胎中取出卵子，培养出一个拥有四个父母的婴儿。”

Three prominent academics in medicine and law sounded an alarm about the possible consequences in a paper published this year.

医学与法律领域的三位知名学者在今年发表的一篇论文中对这种技术可能带来的后果发出了警告。

“IVG may raise the specter of ‘embryo farming’ on a scale currently unimagined, which might exacerbate concerns about the devaluation of human life,” Dr. Eli Y. Adashi, a medical science professor at Brown; I. Glenn Cohen, a Harvard Law School professor; and Dr. George Q. Daley, dean of Harvard Medical School, wrote in the journal Science Translational Medicine.

“IVG可能会使‘胚胎养殖’的恐惧增加到目前难以想象的程度，由此加剧人们对人命贬值的担忧，”布朗大学(Brown)医学教授埃利·Y·阿达希(Eli Y. Adashi)、哈佛法学院教授I·格伦·科恩(I. Glenn Cohen)和哈佛医学院院长乔治·Q·戴利(George Q. Daley)在发表于《科学转化医学》(Science Translational Medicine)杂志的一篇文章中写道。

Still, how soon IVG might become a reality in human reproduction is open to debate.

不过，对于IVG会多快成为人类繁殖的一种现实，业内依然存在争议。

“I wouldn’t be surprised if it was 5 years, and I wouldn’t be surprised if it was 25 years,” said Jeanne Loring, a researcher at the Scripps Research Institute, who, with the San Diego Zoo, hopes to use IVG to increase the population of the nearly extinct northern white rhino.

“如果5年就出现，我不会感到吃惊;若是25年，也不奇怪，”斯克里普斯研究院(Scripps Research Institute)研究员珍妮·洛林(Jeanne Loring)说。她在与圣迭戈动物园(San Diego Zoo)合作，希望能用IVG增加几近灭绝的北方白犀牛的数量。

Loring said that when she discussed IVG with colleagues who initially said it would never be used with humans, their skepticism often melted away as the conversation continued. But not everyone is convinced that IVG will ever become a regularly used process in human reproduction — even if the many ethical issues are resolved.

洛林表示，当她和一开始认为IVG永远不会用于人类的同事讨论这项技术时，他们的态度往往会随着谈话的展开而转变。但不是所有人都相信IVG会成为人类繁殖中的常用手段——哪怕许多伦理问题最终得到解决。

“People are a lot more complicated than mice,” said Susan Solomon, chief executive of the New York Stem Cell Foundation. “And we’ve often seen that the closer you get to something, the more obstacles you discover.”

“人类比老鼠复杂得多，”纽约干细胞基金会(New York Stem Cell Foundation)首席执行官苏珊·所罗门(Susan Solomon)说。“而且我们往往发现，你越靠近某样东西，遇到的障碍就越多。”

IVG is not the first reproductive technology to challenge the basic paradigm of baby-making. Back when in vitro fertilization was beginning, many people were horrified by the idea of creating babies outside the human body. And yet, IVF and related procedures have become so commonplace that they now account for about 70,000, or almost 2 percent, of the babies born in the United States each year. According to the latest estimate, there have been more than 6.5 million babies born worldwide through IVF and related technologies.

IVG不是第一个挑战基本造人模式的生殖技术。回到体外受精开始的阶段，有许多人被体外造人的想法吓到了。然而，体外受精及相关程序已经变得十分常见，每年有7万例之多，或说占美国每年出生的新生婴儿的近2%。据最新的估计，全世界有超过650万婴儿是借助体外受精及相关技术孕育的。

Of course, even IVF is not universally accepted. The Catholic Church remains firm in its opposition to in vitro fertilization, in part because it so often leads to the creation of extra embryos that are frozen or discarded.

当然，就连体外受精技术也没有被普遍接受。天主教会依然坚定地反对它，部分原因在于它往往会产生多余的胚胎，它们会被冷冻或遭舍弃。

IVG requires layers of complicated bioengineering. Scientists must first take adult skin cells — other cells would work as well or better, but skin cells are the easiest to get — and reprogram them to become embryonic stem cells capable of growing into different kinds of cells.

IVG需要一道道复杂的生物工程程序。科学家必须首先从成人身上提取皮肤细胞——其他细胞也可以用，甚至更好，但皮肤细胞是最容易获得的——将它们改造成可以长成不同种类细胞的胚胎干细胞。

Then, the same kind of signaling factors that occur in nature are used to guide those stem cells to become eggs or sperm. (Cells taken from women could be made to produce sperm, the researchers say, but the sperm, lacking a Y chromosome, would produce only female babies.)

然后，利用与发生在自然界中同样的信号因子引导这些干细胞长成卵子或精子(研究人员表示，从女性身上提取的细胞也可以被用来制造精子，但这种精子缺乏一种Y染色体，只能长成女婴)。

Last year, researchers in Japan, led by Katsuhiko Hayashi, used IVG to make viable eggs from the skin cells of adult female mice, and produced embryos that were implanted into female mice, who then gave birth to healthy babies.

去年，由林胜彦(Katsuhiko Hayashi，音)领导的日本研究团队利用IVG技术，将从成年雌鼠身上提取的皮肤细胞变成可以生长发育的卵子，培养成胚胎后植入雌鼠体内，最后生出了健康的幼鼠。