05/07/2014 NPR
THE TIME HAS COME!
First Embryonic Stem Cells Cloned From A Man's Skin
by RICHARD HARRIS
April 17, 2014 2:14 PM ET
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All Things Considered 3 min 16 sec
This mouse egg (top) is being injected with genetic material from an adult cell to ultimately create an embryo ― and, eventually, embryonic stem cells. The process has been difficult to do with human cells.
James King-Holmes/Science Source
Eighteen years ago, scientists in Scotland took the nuclear DNA from the cell of an adult sheep and put it into another sheep's egg cell that had been emptied of its own nucleus. The resulting egg was implanted in the womb of a third sheep, and the result was Dolly, the first clone of a mammal.
Dolly's birth set off a huge outpouring of ethical concern ― along with hope that the same techniques, applied to human cells, could be used to treat myriad diseases.
But Dolly's birth also triggered years of frustration. It's proved very difficult to do that same sort of DNA transfer into a human egg.
Shots - Health News
Scientists Clone Human Embryos To Make Stem Cells
Last year, scientists in Oregon said they'd finally done it, using DNA taken from infants. Robert Lanza, chief scientific officer at Advanced Cell Technology, says that was an important step, but not ideal for medical purposes.
"There are many diseases, whether it's diabetes, Alzheimer's or Parkinson's disease, that usually increase with age," Lanza says. So ideally scientists would like to be able to extract DNA from the cells of older people ― not just cells from infants ― to create therapies for adult diseases.
Lanza's colleagues, including Young Gie Chung at the CHA Stem Cell Institute in Seoul, Korea (with labs in Los Angeles as well), now report success.
Writing in the journal Cell Stem Cell, they say they started with nuclear DNA extracted from the skin cells of a middle-age man and injected it into human eggs donated by four women. As with Dolly, the women's nuclear DNA had been removed from these eggs before the man's DNA was injected. They repeated the process ― this time starting with the genetic material extracted from the skin cells of a much older man.
Dolly, the first mammal to be genetically cloned from adult cells, poses for the camera in 1997 at the Roslin Institute in Edinburgh, Scotland.
Paul Clements/AP
"What we show for the first time is that you can actually take skin cells, from a middle-aged 35-year-old male, but also from an elderly, 75-year-old male" and use the DNA from those cells in this cloning process, Lanza says.
They injected it into 77 human egg cells, and from all those attempts, managed to create two viable cells that contained DNA from one or the other man. Each of those two cells is able to divide indefinitely, "so from a small vial of those cells we could grow up as many cells as we would ever want," Lanza says.
They look like the cells in a human embryo ― in fact, they're called embryonic stem cells. And with a bit of coaxing, these cells could, theoretically, be prodded to turn into any sort of human cell ― nerve, heart, liver and pancreas, for example. That's what makes them potentially useful for treating all sorts of diseases.
In the 18 years since researchers cloned a sheep, scientists have found another way to produce cloned human cell lines. And the other technique, which produces "induced pluripotent stem cells," skips the step that requires a human egg cell, so some people find it less fraught, ethically.
It also means that finally getting the sheep technology to work with cells from adult humans may not turn out to be a turning point for this technology, after all.
"We now have two ways and we're not sure which of the two methods is likely to work best," Lanza says.
Ideally he would like to screen millions of adults and choose just a hundred or so whose genes would make them good DNA donors. He'd like to see a library of cells created with those carefully chosen genes.
In principle, scientists could produce a series of cell lines that would allow a close match for the majority of would-be cell recipients ― just as transplant surgeons currently seek a close match for organ donors.
Physicians could also extract DNA from the person who is going to receive the cellular transplant ― creating a patient-specific treatment ― though that would end up being far more expensive than drawing from a library of ready-made cells.
Paul Knoepfler at the University of California, Davis, School of Medicine is excited about this advance from a medical point of view. But he says this does mean we could be getting closer to being able to go beyond cloned cell lines to cloning an entire human being.
"I don't think that's coming anytime soon, but certainly this kind of technology could be abused by some kind of rogue scientist," Knoepfler says.
And while many people consider that idea dangerous and repugnant, it is not broadly illegal.
Making Personalized Stem Cells
Scientists report that they have successfully cloned human embryos from an elderly man's skin cells. Here's how they could eventually use the technology to create new therapies for a patient.
Source: Mitalipov Lab/OHSU
Credit: Adapted for NPR by Alyson Hurt
cloning
bioethics
embryonic stem cells
stem cells
05/07/2014 NPR.National Public Radio
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💧THE TIME HAS COME! 怖い世界 !!!
2014年05月06日 06時00分29秒
💧75歳の男性の肌からDNAを採取しクローン細胞を作ることに成功
国によっては人間を対象としたクローン研究を禁止しているところもあり、クローン研究は議論の的となっていますが、そんな中でアメリカの研究チームが成人男性の肌から採取したDNAを使って人間の細胞をクローニングすることに成功しました。
First Embryonic Stem Cells Cloned From A Man's Skin : Shots - Health News : NPR
http://www.npr.org/blogs/health/2014/04/17/303658757/first-embryonic-stem-cells-cloned-from-a-mans-skin
Scientists Make First Embryo Clones From Adults - WSJ.com
http://online.wsj.com/news/articles/SB10001424052702303626804579507593658361428
今から18年前に羊を使った実験で初めてほ乳類のクローンが誕生しました。ドリーと呼ばれたクローン羊を生み出した技術は、人間に応用されれば無数の病の治療法として使える可能性がありながらも、倫理の面で大きな問題を抱えていました。実際に、中国ではクローン豚を大量生産する世界最大の「クローン工場」が作られ、物議をかもしています。
今回の研究はオレゴン健康科学大学のRobert Lanza教授やCHA UNIVERSITYのYoung Gie Chung教授らが率いるチームによって医療への転用を目的に行われたもの。
Lanza教授らは2013年の時点で既に幼児と胎児の細胞からクローンを作ることに成功していましたが、人間は年を追うごとに糖尿病やアルツハイマー病、パーキンソン病といった病気になる可能性が増えていくものなので、成人のDNAから人工細胞を複製できなければ、この技術の価値は半減してしまう、という点が問題でした。
また、ごく初期段階の胎児から細胞を採取した場合、胎児を破壊してしまうという問題も抱えていました。例えまだこの世に生まれていなくても、これは命を奪うことと同じである、という声が上がっていたのです。
そこで研究チームは35歳の男性と75歳の男性ドナーの肌からDNAを採取。未受精の卵子からDNAを取り出して、代わりに大人のドナーから採取したDNAを入れました。すると卵子は自動的に再プログラムを始め、胚盤胞にまで育ちます。
胚盤胞をラボで培養したところ胚盤胞からはドナーのDNAと完全に合致する幹細胞が生まれ、幹細胞はその後、心臓細胞のような別のタイプの組織に変化。この組織は拒絶反応なく患者に移植できるため多くの疾病の治療に役立つと考えられています。Lanza教授と共に研究を行っていた発達生物学者のShoukhrat Mitalipov氏は「我々の研究が正しかったことが証明され、とても嬉しいです」と語りました。
今回の手法はクローン羊の作り方とは別の方法で、「今我々にはクローンを作るために2つの方法がありますが、どちらの方法が優れているのかは私にはわかりません」とLanza教授は語ります。
ただし実験が成功したといっても、これがただちに完全な人間のクローンが作れるという結論に結びつくわけではありません。研究者たちは何年ものあいだ猿のクローンを作ろうとしていますが、いまだに成功例はゼロ。ウサギや羊、犬などのクローン作りには成功していますが、それさえ何年にも渡って数え切れないほどの卵子や胎児を使った実験に失敗してたどり着いたのです。
科学者の中には医学的観点からクローン技術の進歩に興奮する人もいますが、一方で、この技術は人間のクローン作成への境界線を越えてしまった、として慎重な声も上がっています。今回作られた胚盤胞を子宮に戻してもクローン人間は生まれませんが、いずれ科学の知識を持った人々が技術を乱用する恐れも十分に考えられるのです。
by Kevin O'Mara