科学家朝克隆人又迈近一步

The scientists first removed the DNA from an unfertilized human egg, and then inserted a patient's mature skin cell─containing the patient's DNA─into that egg. Next, they prompted a chemical reaction, causing the cells to fuse and begin development.
科学家首先从一个未受精的卵子中取出DNA，然后在卵子中植入含有病人DNA的成熟皮肤细胞。之后科学家触发一个化学反应，引发细胞融合、发育。

That led to a blastocyst, a hollow ball of 50 to 100 cells. For a fetus to form, the blastocyst must be implanted in a womb. An inner clump of cells in the blastocyst goes on to form the embryo, while an outer layer goes on to make the placenta.
这导致胚泡的形成。胚泡是含有50个至100个细胞的中空球。想要形成胎儿，胚泡必须植入子宫。胚泡中的内层细胞随后形成胚胎，外层细胞则形成胎盘。

For the tissue-growing experiment, the researchers focused on the clump of cells containing embryonic stem cells.
对于培养组织的实验来说，研究人员关注的是含有胚胎干细胞的这群细胞。

With the help of certain 'growth' chemicals, they were able to transform the stem cells into 'various cell lines and tissues, including beating human heart cells,' said Shoukhrat Mitalipov, a development biologist at Oregon Health and Science University, in Portland, Ore., and a lead author of the study.
俄勒冈州波特兰市俄勒冈健康与科学大学的发育生物学家米塔利波夫(Shoukhrat Mitalipov)说，在某些“增长”化学物质的帮助下，他们能够将干细胞变成各种细胞系和组织，包括人类心脏细胞。米塔利波夫是该研究的主要作者之一。

The achievement is a long way from creating a cloned human embryo.
研究人员所取得的成就距离创造克隆人类胚胎还有很长的路。

Even if the entire blastocyst had been implanted into a womb, it wouldn't have yielded a human clone. The blastocyst was 'missing a few cell types that it would need to implant,' as well as suffering other deficiencies, said Dr. Mitalipov.
即使整个胚泡被植入子宫，它也不会产生出克隆人。米塔利波夫博士说，胚泡还缺少一些其需要植入的细胞类型，同时也存在其它缺陷。

Never mind the prospect of cloned humans; despite years of experiments, scientists have failed to clone monkeys.
就更不用提克隆人的前景了──尽管经过多年实验，科学家还未能成功克隆猴子。

Dr. Mitalipov said his lab had tried transplanting entire blastocysts into a monkey's womb, but those experiments hadn't yielded a single successful pregnancy.
米塔利波夫博士说，他的实验室曾尝试将整个胚泡植入猴子的子宫，但这些实验尚未形成一次成功的妊娠。

'We don't know why this is,' said Dr. Mitalipov. 'You can make embryonic stem cells but it doesn't mean the embryo will implant.'
米塔利波夫博士说，我们不知道这是为什么，你可以创造出胚胎干细胞，但这并不意味着胚胎能够被植入。

He speculates that one reason why it may be more difficult to clone monkeys and humans is because the egg cells are more fragile than those of other species.
他推测克隆猴子和人类的难度更大的原因之一可能是和其它物种相比，猴子和人类的卵细胞更脆弱。

Dr. Mitalipov's main goal is to use cloning to treat illnesses. He next plans to use lab-made tissue and see if he can successfully treat a degenerative, blindness-causing eye disease in monkeys.
米塔利波夫博士的主要目标是使用克隆技术治病。他下一步计划使用实验室培养的组织，并观察他是否能成功地治疗一种发生在猴子身上的、可导致失明的退行性疾病。