dxy

来自韦克福里斯特大学和哈佛大学的研究人员在星期日对外宣称， 他们已经在有保护胎儿作用的羊水中找到了丰富的干细胞并已利用干细胞培育出包括脑、肝和骨在内的多种类型的组织细胞，这与此前饱受争议的从胚胎提取干细胞的破坏性研究有很大不同。研究人员发现， 提取自羊水中的干细胞毫不逊色于胚胎干细胞，而且该提取过程不会对母亲和胎儿造成任何危险。

韦克福里斯特的再生医学研究所所长，同时也是该研究带头人的Anthony Atala博士在其位于北卡罗来纳州温斯顿塞勒姆的实验室开展了此次的研究，这一次的研究发现是所谓的再生医学领域中的最新进展。在4月份的时候，Atala和他的同事就利用实验室培养出来的活组织为7 位年轻病人进行了膀胱再造。

Atala博士的研究团队花费了数年时间才得以确定羊水干细胞确实是料真材实，“能用于培育许多有治疗价值的细胞。”在受孕第一天即已产生的人类胚胎干细胞标记使干细胞得以衍生成超过220种的组织细胞类型。因此，用Atala博士”希望羊水能为组织修复和人工改造器官提供充足的干细胞”。

不过，研究人员也指出，羊水干细胞究竟能培育出多少种细胞类型还是个未知数，而且要在病人身上开展初步测试还要再等上几年。

此前在11月份举行的一场核心研究会议上，瑞士研究人员Simon Hoerstrup宣称，他已成功利用羊水干细胞培育出心瓣膜细胞。Simon Hoerstrup的研究报告还尚未在任何科学杂志上公开发表。Atala博士说他们发表在<<自然生物科技>>杂志上的研究比Simon Hoerstrup的研究要前进了一大步。另外，他说羊水中的干细胞更具优势，能够培育出更有医学价值的替代器官。同时该研究还发现了其他可供利用的干细胞株。

不过，很多人，包括布什总统，都一致反对以任何理由破坏胚胎。自2001年以来，布什政府就严重限制联邦资金用于胚胎干细胞研究，迫使许多科学家不得不寻找其它干细胞来源。

羊水干细胞“显然能衍生出众多重要的细胞类型，但是还不能与胚胎干细胞相媲美。” 身为干细胞先进技术公司首席科学家的Robert Lanza博士说道，“但不管怎么样，我认为Atala博士的研究将干细胞研究推向了一个崭新的高度。”

此次的研究中，Atala博士的研究团队不仅从羊水中众多的细胞中成功提取出少量干细胞。 更令人兴奋的是，一些羊水干细胞的DNA 中含有Y染色体，这就意味着这些干细胞来自于胎儿本身而不是母亲。

身为哈佛大学干细胞研究人员的George Daley博士对此说道，这一研究发现大大提高了准爸爸妈妈们将羊水干细胞冷冻起来以备其子女将来置换组织之需的可能性，而且利用干细胞培育的组织植入自身体内不会产生免疫排斥反应。不过，从去年开始就着手进行克隆人类胚胎以制造干细胞的研究工作的Daley博士同时指出，人类胚胎干细胞研究不宜因为此次羊水干细胞的研究发现而就从此偃旗息鼓。“羊水干细胞有足够的理由成为研究的新宠， 但它们不能成为胚胎干细胞的替代品，胚胎干细胞研究的突破可以帮助解决许多关于早期人类发展的有趣问题，而羊水干细胞研究则不能”。

http://news.yahoo.com/s/ap/20070108/ap_on_he_me/stem_cells

Scientists reported Sunday they had found a plentiful source of stem cells in the fluid that cushions babies in the womb and produced a variety of tissue types from these cells — sidestepping the controversy over destroying embryos for research.

Researchers at Wake Forest University and Harvard University reported the stem cells they drew from amniotic fluid donated by pregnant women hold much the same promise as embryonic stem cells. They reported they were able to extract the stem cells without harm to mother or fetus and turn their discovery into several different tissue cell types， including brain， liver and bone.

”Our hope is that these cells will provide a valuable resource for tissue repair and for engineered organs as well，” said Dr. Anthony Atala， head of Wake Forest's regenerative medicine institute and senior researcher on the project.

It took Atala's team some seven years of research to determine the cells they found were truly stem cells that ”can be used to produce a broad range of cells that may be valuable for therapy.”

However， the scientists noted they still don't know exactly how many different cell types can be made from the stem cells found in amniotic fluid. They also said that even preliminary tests in patients are years away.

Still， Atala said the research reported in the scientific journal Nature Biotechnology expands far beyond similar work discussed at a heart research conference in November. There， Swiss researcher Simon Hoerstrup said he managed to turn amniotic fluid stem cells into heart cells that could be grown into replacement valves. Hoerstrup has yet to publish his work in a scientific journal.

Atala said the new research has found even more promising stem cells with the potential to turn into many more medically useful replacement parts.

”We have other cell lines cooking，” Atala said.

The hallmark of human embryonic stem cells， which are created in the first days after conception， is the ability to turn into any of the more than 220 cell types that make up the human body. Researchers are hopeful they can train these primordial cells to repair damaged organs in need of healthy cells.

However， many people， including President Bush， oppose the destruction of embryos for any reason. The Bush administration has severely restricted federal funding for the embryo work since 2001， leading many scientists to search for alternative stem cell sources.

The cells from amniotic fluid ”can clearly generate a broad range of important cell types， but they may not do as many tricks as embryonic stem cells，” said Dr. Robert Lanza， chief scientist at the stem cell company Advanced Cell Technology. ”Either way， I think this work represents a giant step forward for stem cell research.”

It's the latest advance in the so-called regenerative medicine field that has sprung from Atala's lab in Winston-Salem， N.C. In April， Atala and his colleagues rebuilt bladders for seven young patients using live tissue grown in the lab.

In the latest work， Atala's team extracted a small number of stem cells swimming among the many other cell types in the amniotic fluid. One of the more promising aspects of the research is that some of the DNA of the amnio stem cells contained Y chromosomes， which means the cells came from the babies rather than the pregnant moms.

Dr. George Daley， a Harvard University stem cell researcher， said that finding raises the possibility that someday expectant parents can freeze amnio stem cells for future tissue replacement in a sick child without fear of immune rejection.

Nonetheless， Daley said the discovery shouldn't be used as a replacement for human embryonic stem cell research.

”While they are fascinating subjects of study in their own right， they are not a substitute for human embryonic stem cells， which allow scientists to address a host of other interesting questions in early human development，” said Daley， who began work last year to clone human embryos to produce stem cells.

编辑：蓝色幻想