美国国家公共电台 NPR Embryo Experiments Reveal Earliest Human Development, But Stir Ethical Debate

 

RACHEL MARTIN, HOST:

Scientists doing embryo¹ research are facing some sensitive questions over a new generation of scientific experiments, questions like how long should scientists be allowed to keep human embryos² alive in their labs to study them? And should entities³ that they create from stem cells resembling human embryos be treated the same way? NPR's health correspondent Rob Stein visited a lab that's at the forefront of this provocative⁴ research, and he brings us now the first of two reports.

ROB STEIN, BYLINE⁵: So what are we going to see first?

ALI BRIVANLOU: A human embryo that is attached and grown for 13 days in a petri dish.

STEIN: Ali Brivanlou runs the lab at The Rockefeller University in midtown Manhattan.

So this is an embryo that - where you were able to keep it alive in the laboratory...

BRIVANLOU: Exactly.

STEIN: ...Up until day...

BRIVANLOU: Day 13.

STEIN: And had it been done before?

BRIVANLOU: Never.

STEIN: For decades, scientists thought the longest an embryo could survive outside the womb was only about half that long - only about a week tops. So this is the first time scientists can actually see living human embryos at this crucial stage of development and study them at a time when they're usually hidden in a woman's womb.

BRIVANLOU: And women don't even know they are pregnant at that stage, so it has always been a big black box.

STEIN: Brivanlou arranged for one of his colleagues to show me.

BRIVANLOU: I ask him to make sure that he has a real sample for you to see with your own eyes so that you can appreciate the beauty in their own glory. It's really one of the most beautiful things I have ever seen in my life.

STEIN: Brivanlou's colleague Gist⁶ Croft pulls out some samples. Turns out, he's going to show me several embryos, starting with one that's 12 days old.

GIST CROFT: So you can see this with the naked eye. In the middle of this well, if you look down, there's a little white speck⁷ that looks like a grain of sand or a piece of dust in this well right here. I don't know if you can - can you see that?

STEIN: Yeah, it looks like a tiny little white translucent⁸ dot.

CROFT: That's it.

STEIN: Croft carefully places it on a big microscope and pulls a heavy black curtain closed.

CROFT: Would you like to look through the microscope?

STEIN: Yeah.

BRIVANLOU: OK.

STEIN: Croft helps me bring the embryo into focus.

Oh, yeah, I can see...

CROFT: Better?

STEIN: I can see the - oh, wow. Wow, that's, like, kind of beautiful.

It is quite stunning⁹. It looks like a fragile ball of overlapping¹⁰ bubbles that's sort of shimmering¹¹ in a silvery light, but it's also a little, well, funny looking.

So that looks like a (laughter) well, I mean, it kind of just looks like a - kind of a translucent hairy ball actually.

CROFT: Yes.

STEIN: Croft and Brivanlou get excited that I noticed what looked like little hairs reaching out from all sides because that's exactly what scientists would expect embryos to do at this stage if they were in the womb - search for just the right spot to nestle in.

CROFT: They're doing the reaching out and attaching that they normally do into uterus cells, but here they're doing it onto plastic.

STEIN: Wow, so they're behaving like they would - this embryo is behaving like it would if it was actually in the womb.

CROFT: That's right. It's reproducing certain key features of what it's normally doing in the womb.

STEIN: Scientists thought embryos could only do that sort of thing if they were getting instructions from their mother's body about what to do next - not all alone in some plastic dish.

BRIVANLOU: The amazing thing is that it's doing its thing without any information from mom - completely unexpected to me. It just has all the information already in it. That was mind-blowing to me.

STEIN: The embryos also start pumping out hormones¹² and start organizing themselves, all by themselves, to form the cells needed to create all the tissues and organs that make up the human body. So Brivanlou and his colleagues think they could learn lots of things by studying them that could help stop miscarriages¹³, treat infertility¹⁴, prevent birth defects.

BRIVANLOU: The only way to understand what goes wrong is to understand what happens normally or as normally as we can so we can prevent all of this.

STEIN: But that would mean studying embryos beyond 14 days and Brivanlou can't keep these embryos alive any longer to keep studying them. Why? Because of a rule that says scientists should not conduct experiments on human embryos that are more than 14 days old. So Brivanlou decided¹⁵ he had no choice but to pull the plug on these experiments.

BRIVANLOU: The decision about pulling the plug was probably the toughest decision I've made in my scientific career. It was sad for me. It was sad.

STEIN: The 14-day rule was adopted decades ago to avoid raising too many ethical¹⁶ questions. It's a guideline in the U.S. but law in some other countries. Fourteen days is when the central nervous system starts forming, starting with something called the primitive¹⁷ streak¹⁸. It's also usually when an embryo can't split into twins anymore. So the idea is that's when it truly becomes an individual. But that was before anyone thought it would ever be possible to go beyond two weeks. So Brivanlou says it's time to rethink the 14-day rule.

BRIVANLOU: It's time to reopen that debate. This is the moment. I think we are here. It would be a travesty¹⁹ to decide that somehow ignorance is bliss²⁰.

STEIN: And Brivanlou's not alone. There's a big debate about this going on in the United States, Britain and other countries. Insoo Hyun is a bioethicist at the Case Western Reserve University. He points out that these are embryos that were donated for research by couples who were finished with infertility treatments.

INSOO HYUN: You have to realize that with these embryos they are being used for research. That decision has been made. Now, the question is how long can you study them before they have to be destroyed? So given that it has to be destroyed, some would argue that it's best to get as much information as possible scientifically from it before you destroy it.

STEIN: Now, some people think it's morally repugnant to use human embryos for any kind of research at any stage of their development. And lifting the 14-day rule, that would just make matters worse. But the idea of extending the 14-day rule even makes some people who support embryo research uncomfortable, especially without first coming up with another clear stopping point. Hank Greely is a bioethicist at Stanford.

HANK GREELY: Unless there was something really important we could learn from doing research with human embryos, I wouldn't allow research beyond 14 days because at some point experimentation²¹ with it seems to really draw into question whether we're using humans or things that are well along the path to humans purely²² as guinea pigs and purely as experimental animals.

STEIN: So as that debate continues, Brivanlou and his colleagues are trying something else. They're using stem cells to create things that resemble primitive human embryos in their lab, but that's controversial too. Rob Stein, NPR News, New York.

(SOUNDBITE OF PHILANTHROPE'S "RELAX")

1 embryo   

n.胚胎，萌芽的事物

参考例句：

• They are engaging in an embryo research.他们正在进行一项胚胎研究。
• The project was barely in embryo.该计划只是个雏形。

2 embryos   

n.晶胚；胚，胚胎( embryo的名词复数 )

参考例句：

• Somatic cells of angiosperms enter a regenerative phase and behave like embryos. 被子植物体细胞进入一个生殖阶段，而且其行为象胚。 来自辞典例句
• Evolution can explain why human embryos look like gilled fishes. 进化论能够解释为什么人类的胚胎看起来象除去了内脏的鱼一样。 来自辞典例句

3 entities   

实体对像； 实体，独立存在体，实际存在物( entity的名词复数 )

参考例句：

• Our newspaper and our printing business form separate corporate entities. 我们的报纸和印刷业形成相对独立的企业实体。
• The North American continent is made up of three great structural entities. 北美大陆是由三个构造单元组成的。

4 provocative   

adj.挑衅的，煽动的，刺激的，挑逗的

参考例句：

• She wore a very provocative dress.她穿了一件非常性感的裙子。
• His provocative words only fueled the argument further.他的挑衅性讲话只能使争论进一步激化。

5 byline   

n.署名；v.署名

参考例句：

• His byline was absent as well.他的署名也不见了。
• We wish to thank the author of this article which carries no byline.我们要感谢这篇文章的那位没有署名的作者。

6 gist   

n.要旨；梗概

参考例句：

• Can you give me the gist of this report?你能告诉我这个报告的要点吗？
• He is quick in grasping the gist of a book.他敏于了解书的要点。

7 speck   

n.微粒，小污点，小斑点

参考例句：

• I have not a speck of interest in it.我对它没有任何兴趣。
• The sky is clear and bright without a speck of cloud.天空晴朗，一星星云彩也没有。

8 translucent   

adj.半透明的；透明的

参考例句：

• The building is roofed entirely with translucent corrugated plastic.这座建筑完全用半透明瓦楞塑料封顶。
• A small difference between them will render the composite translucent.微小的差别,也会使复合材料变成半透明。

9 stunning   

adj.极好的；使人晕倒的

参考例句：

• His plays are distinguished only by their stunning mediocrity.他的戏剧与众不同之处就是平凡得出奇。
• The finished effect was absolutely stunning.完工后的效果非常美。

10 overlapping   

adj./n.交迭（的）

参考例句：

• There is no overlapping question between the two courses. 这两门课程之间不存在重叠的问题。
• A trimetrogon strip is composed of three rows of overlapping. 三镜头摄影航线为三排重迭的象片所组成。

11 shimmering   

v.闪闪发光，发微光( shimmer的现在分词 )

参考例句：

• The sea was shimmering in the sunlight. 阳光下海水波光闪烁。
• The colours are delicate and shimmering. 这些颜色柔和且闪烁微光。 来自辞典例句

12 hormones   

n. 荷尔蒙，激素 名词hormone的复数形式

参考例句：

• This hormone interacts closely with other hormones in the body. 这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。
• The adrenals produce a large per cent of a man's sex hormones. 肾上腺分泌人体的大部分性激素。

13 miscarriages   

流产( miscarriage的名词复数 )

参考例句：

• Miscarriages are usually caused by abnormal chromosome patterns in the fetus. 流产通常是因为胎儿的染色体异常造成的。
• Criminals go unpunishedareconvicted and are miscarriages of justice. 罪犯会逍遥法外，法律会伤及无辜，审判不公时有发生。

14 infertility   

n.不肥沃，不毛；不育

参考例句：

• It is the Geneva, Switzerland-based Biotech Company's second recombinant infertility drug. 它是瑞士生物技术公司在日内瓦的公司生产的第二种重组治疗不孕症的药。 来自英汉非文学 - 生命科学 - 生物技术制药疫苗
• Endometritis is a cause of infertility. 子宫内膜炎是不育的原子。 来自辞典例句

15 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

16 ethical   

adj.伦理的，道德的，合乎道德的

参考例句：

• It is necessary to get the youth to have a high ethical concept.必须使青年具有高度的道德观念。
• It was a debate which aroused fervent ethical arguments.那是一场引发强烈的伦理道德争论的辩论。

17 primitive   

adj.原始的；简单的；n.原(始)人，原始事物

参考例句：

• It is a primitive instinct to flee a place of danger.逃离危险的地方是一种原始本能。
• His book describes the march of the civilization of a primitive society.他的著作描述了一个原始社会的开化过程。

18 streak   

n.条理，斑纹，倾向，少许，痕迹；v.加条纹，变成条纹，奔驰，快速移动

参考例句：

• The Indians used to streak their faces with paint.印第安人过去常用颜料在脸上涂条纹。
• Why did you streak the tree?你为什么在树上刻条纹？

19 travesty   

n.歪曲，嘲弄，滑稽化

参考例句：

• The trial was a travesty of justice.这次审判嘲弄了法律的公正性。
• The play was,in their view,a travesty of the truth.这个剧本在他们看来是对事实的歪曲。

20 bliss   

n.狂喜，福佑，天赐的福

参考例句：

• It's sheer bliss to be able to spend the day in bed.整天都可以躺在床上真是幸福。
• He's in bliss that he's won the Nobel Prize.他非常高兴，因为获得了诺贝尔奖金。

21 experimentation   

n.实验，试验，实验法

参考例句：

• Many people object to experimentation on animals.许多人反对用动物做实验。
• Study and analysis are likely to be far cheaper than experimentation.研究和分析的费用可能要比实验少得多。

22 purely   

adv.纯粹地，完全地

参考例句：

• I helped him purely and simply out of friendship.我帮他纯粹是出于友情。
• This disproves the theory that children are purely imitative.这证明认为儿童只会单纯地模仿的理论是站不住脚的。