這幾天最大的新聞應該就是
今天發表在 science 以及 cell 上面的這兩篇論文

先貼英文新聞

By Gretchen Vogel
ScienceNOW Daily News
20 November 2007
Scientists have managed to reprogram human skin cells directly into cells
that look and act like embryonic stem (ES) cells. The technique makes it
possible to generate patient-specific stem cells to study or treat disease
without using embryos or oocytes--and therefore could bypass the ethical
debates that have plagued the field. "This is like an earthquake for both the
science and politics of stem cell research," says Jesse Reynolds, policy
analyst for the Center for Genetics and Society in Oakland, California.

The work builds on a study published last year by Shinya Yamanaka of Kyoto
University in Japan, which showed that mouse tail cells could be transformed
into ES-like cells by inserting four genes (ScienceNOW, 3 July 2006). Those
genes are normally switched off after embryonic cells differentiate into the
various cell types. In June this year, Yamanaka and another group reported
that the cells were truly pluripotent, meaning that they had the potential to
grow into any tissue in the body (ScienceNOW, 6 June).

Now the race to repeat the feat in human cells has ended in a tie: Two groups
report today that they have reprogrammed human skin cells into so-called
induced pluripotent cells (iPCs). In a paper published online in Cell,

Yamanaka and his colleagues show that their mouse technique works with human
cells as well. And in a paper published online in Science, James Thomson of
the University of Wisconsin, Madison, and his colleagues report success in
reprogramming human cells, again by inserting just four genes, two of which
are different from those Yamanaka uses.

In the new work, Yamanaka and his colleagues used a retrovirus to ferry into
adult cells the same four genes they had previously used to reprogram mouse
cells: OCT3/4, SOX2, KLF4, and c-MYC. They reprogrammed cells taken from the
facial skin of a 36-year-old woman and from connective tissue from a
69-year-old man. Roughly one iPC cell line was produced for every 5000 cells
the researchers treated using the technique, an efficiency that enabled them
to produce several cell lines from each experiment.

Thomson's team started from scratch, identifying its own list of 14 candidate
reprogramming genes. Like Yamanaka's group, the team used a systematic
process of elimination to identify four factors: OCT3 and SOX2, as Yamanaka
used, and two different genes, NANOG and LIN28. The group reprogrammed cells
from fetal skin and from the foreskin of a newborn boy. The researchers were
able to transform about one in 10,000 cells, less than Yamanaka's technique
achieved, Thomson says, but still enough to create several cell lines from a
single experiment.

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這個研究用最簡單的講法
就是延伸之前做複製技術的原理

原本做複製動物的原理是把成體細胞的細胞核
打到卵細胞中，讓卵細胞中可以誘導分化的 protein 重新建構這個細胞
然後變成類似胚胎幹細胞的東西，重新產生一個新的個體

這次的實驗就是直接找出那些 "protein" 是什麼
然後直接把一個成體細胞做重建
在今年七月就已經有一篇 Nature 的論文提到這件事
不過當時的實驗似乎仍有缺陷
這次又改了兩個基因，所以現在是
OCT3/4 C-myc KLF SOX2 這四個

由於美國時間還沒到
先貼上七月那篇的 summery

Generation of germline-competent induced pluripotent stem cells
Keisuke Okita1, Tomoko Ichisaka1,2 & Shinya Yamanaka1,2

Department of Stem Cell Biology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
CREST, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
Correspondence to: Shinya Yamanaka1,2 Correspondence and requests for materials should be addressed to S.Y. (Email: yamanaka@frontier.kyoto-u.ac.jp).


Top of pageAbstractWe have previously shown that pluripotent stem cells can be induced from mouse fibroblasts by retroviral introduction of Oct3/4 (also called Pou5f1), Sox2, c-Myc and Klf4, and subsequent selection for Fbx15 (also called Fbxo15) expression. These induced pluripotent stem (iPS) cells (hereafter called Fbx15 iPS cells) are similar to embryonic stem (ES) cells in morphology, proliferation and teratoma formation; however, they are different with regards to gene expression and DNA methylation patterns, and fail to produce adult chimaeras. Here we show that selection for Nanog expression results in germline-competent iPS cells with increased ES-cell-like gene expression and DNA methylation patterns compared with Fbx15 iPS cells. The four transgenes (Oct3/4, Sox2, c-myc and Klf4) were strongly silenced in Nanog iPS cells. We obtained adult chimaeras from seven Nanog iPS cell clones, with one clone being transmitted through the germ line to the next generation. Approximately 20% of the offspring developed tumours attributable to reactivation of the c-myc transgene. Thus, iPS cells competent for germline chimaeras can be obtained from fibroblasts, but retroviral introduction of c-Myc should be avoided for clinical application.


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論文還沒出來，但大概可以想見大概是什麼樣子
乍聽之下解決了許多道德的問題，但是問題回到複製羊的身上
如果一個成體細胞利用這種方式讓他回到了胚胎幹細胞的時期
再一次的分化，他仍然會帶有當時成體細胞上所受到的 DNA damage
並且加以放大，從幹細胞分化到成體細胞也不是一步跳
而是必須跨過很多步驟，所以應用性到底有多大，我想還需要進一步的研究
有人馬上就跳出來說臍帶血銀行要哭了，我看也是未必
現在就下斷語，或是馬上就充滿希望我想都是不必的