人類的皮膚細胞也能制造出嬰兒了？

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.

世界上第一個試管嬰兒震驚世界近40年之后，我們正面臨著一項新的生殖技術(shù)革命——而它的前景比以往任何時候的體外受精都更具爭議。

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.

研究人員說，在10到20年內(nèi)，科學家們或許就能夠用人類皮膚細胞制造出嬰兒了，這些細胞經(jīng)誘使長成卵子和精子，然后用來產(chǎn)生胚胎，植入子宮。

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.

該技術(shù)名為體外配子法(in vitro gametogenesis，簡稱IVG)，迄今僅在小鼠身上做過實驗。但干細胞生物學家說，IVG用于人類繁殖只是個時間問題——它開啟的可能性將是驚人的。

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技術(shù)，兩個男人也可以生育出生物學意義上的親生孩子：把其中一個父親的皮膚細胞制成卵子，再用另一個父親的精子一起，培養(yǎng)成受精卵即可。而無法生育的女性也可以把皮膚細胞制成卵子，無需經(jīng)歷漫長的、昂貴的刺激卵巢取出卵子的過程。

“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.”

“這令人坐立不安，因為我們不知道這可能導致什么狀況。”加州大學戴維斯分校干細胞研究員保羅·克內(nèi)普夫勒(Paul Knoepfler)說。“你可以想象一個人同時提供卵子和精子，幾乎就像克隆自己一樣。你還可以想象，卵子變得如此容易獲得，以至于可以生育出經(jīng)過設計的嬰兒。”

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.

有些科學家甚至提到了“布拉德·皮特情景”(Brad Pitt scenario)的可能性：有人會從酒店的床上或浴缸里搜尋名人的皮膚細胞。或者一個嬰兒可能會擁有法學教授所說的“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.”

喬治華盛頓大學法學教授索尼婭·蘇特(Sonia Suter)在IVG技術(shù)小鼠實驗獲得成功之前就在寫這方面的文章了。她表示：“有些群體想在內(nèi)部進行多重繁殖，你可以找到兩對配偶，每對都形成一個胚胎，然后再從一個胚胎中取出卵子，從另一個胚胎中取出卵子，培養(yǎng)出一個擁有四個父母的嬰兒。”

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

醫(yī)學與法律領(lǐng)域的三位知名學者在今年發(fā)表的一篇論文中對這種技術(shù)可能帶來的后果發(fā)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可能會使‘胚胎養(yǎng)殖’的恐懼增加到目前難以想象的程度，由此加劇人們對人命貶值的擔憂，”布朗大學(Brown)醫(yī)學教授埃利·Y·阿達希(Eli Y. Adashi)、哈佛法學院教授I·格倫·科恩(I. Glenn Cohen)和哈佛醫(yī)學院院長喬治·Q·戴利(George Q. Daley)在發(fā)表于《科學轉(zhuǎn)化醫(yī)學》(Science Translational Medicine)雜志的一篇文章中寫道。

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

不過，對于IVG會多快成為人類繁殖的一種現(xiàn)實，業(yè)內(nèi)依然存在爭議。

“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年就出現(xiàn)，我不會感到吃驚;若是25年，也不奇怪，”斯克里普斯研究院(Scripps Research Institute)研究員珍妮·洛林(Jeanne Loring)說。她在與圣迭戈動物園(San Diego Zoo)合作，希望能用IVG增加幾近滅絕的北方白犀牛的數(shù)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，當她和一開始認為IVG永遠不會用于人類的同事討論這項技術(shù)時，他們的態(tài)度往往會隨著談話的展開而轉(zhuǎn)變。但不是所有人都相信IVG會成為人類繁殖中的常用手段——哪怕許多倫理問題最終得到解決。

“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.”

“人類比老鼠復雜得多，”紐約干細胞基金會(New York Stem Cell Foundation)首席執(zhí)行官蘇珊·所羅門(Susan Solomon)說。“而且我們往往發(fā)現(xiàn)，你越靠近某樣東西，遇到的障礙就越多。”

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不是第一個挑戰(zhàn)基本造人模式的生殖技術(shù)?；氐襟w外受精開始的階段，有許多人被體外造人的想法嚇到了。然而，體外受精及相關(guān)程序已經(jīng)變得十分常見，每年有7萬例之多，或說占美國每年出生的新生嬰兒的近2%。據(jù)最新的估計，全世界有超過650萬嬰兒是借助體外受精及相關(guān)技術(shù)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.

當然，就連體外受精技術(shù)也沒有被普遍接受。天主教會依然堅定地反對它，部分原因在于它往往會產(chǎn)生多余的胚胎，它們會被冷凍或遭舍棄。

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需要一道道復雜的生物工程程序?？茖W家必須首先從成人身上提取皮膚細胞——其他細胞也可以用，甚至更好，但皮膚細胞是最容易獲得的——將它們改造成可以長成不同種類細胞的胚胎干細胞。

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，利用與發(fā)生在自然界中同樣的信號因子引導這些干細胞長成卵子或精子(研究人員表示，從女性身上提取的細胞也可以被用來制造精子，但這種精子缺乏一種Y染色體，只能長成女嬰)。

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，由林勝彥(Katsuhiko Hayashi，音)領(lǐng)導的日本研究團隊利用IVG技術(shù)，將從成年雌鼠身上提取的皮膚細胞變成可以生長發(fā)育的卵子，培養(yǎng)成胚胎后植入雌鼠體內(nèi)，最后生出了健康的幼鼠。