经济学人下载:胚胎干细胞 进展中的干细胞研究

Science and technology
科学技术

Embryonic stem cells
胚胎干细胞

Looking up
进展中的干细胞研究

Stem-cell research is now bearing fruit
干细胞研究开始结出硕果

FOURTEEN years ago James Thomson of the University of Wisconsin isolated stem cells from human embryos.
十四年前，当威斯康辛大学的 James Thomson从人类胚胎细胞中分离出干细胞时，

It was an exciting moment.
人们无不为之欢呼雀跃。

The ability of such cells to morph into any other sort of cell suggested that worn-out or damaged tissues might be repaired,
这种细胞可分裂、转变成为各种器官、组织，因此或将被用于修复、

and diseases thus treated a technique that has come to be known as regenerative medicine.
治疗损伤、病变的组织，这一技术被称为再生医疗。

Since then progress has been erratic and controversial.
但随后这一领域的发展呈现了不稳定性、胚胎细胞的来源问题也引发了社会争议。

But, as two new papers prove, progress there has indeed been.
但是这两篇新论文的发表，证明了干细胞研究取得了一定的进展。

This week's Lancet published results from a clinical trial that used embryonic stem cells in people.
本周《柳叶刀》刊出了胚胎干细胞应用于人体的临床实验的结果。

It follows much disappointment.
人们对这样的消息常常都是失望：

In November, for example, a company in California cancelled what had been the first trial of human embryonic stem cells, in those with spinal injuries.
例如，去年11月，一家位于加州的公司取消了原定的首例人胚胎干细胞在脊髓损伤者身上的试验。

Steven Schwartz of the University of California, Los Angeles, however, claims some success in treating a different problem: blindness.
但是洛杉矶加州大学的Steven Schwartz说他在干细胞治疗其它疾病：如失明，就取得了一些成绩。

His research, sponsored by Advanced Cell Technology, a company based in Massachusetts, involved two patients.
他的研究是在先进细胞技术院的赞助下进行的，这家公司位于马萨诸塞州，两名病患参与了试验，

One has age-related macular degeneration, the main cause of blindness in rich countries.
一位是老年性黄斑变性病患者，这是发达国家盲人病患常见的致盲原因。

The other suffers from Stargardt's macular dystrophy, its main cause in children.
另一位是隐性黄斑营养不良症患者，这是儿童致盲的主要原因。

Dr Schwartz and his team coaxed embryonic stem cells to become retinal pigment epithelium tissue which supports the rod and cone cells that actually respond to light
他的团队诱导胚胎干细胞成为视网膜色素上皮组织细胞－其中的杆细胞及锥晶细胞对光线敏感。

then injected 50,000 of them into one eye of each patient,
然后给每个参试病患的眼睛内注射50,000单位的此种细胞，

with the hope that they would bolster the natural supply of these cells.
希望这些细胞能在体内像原有细胞一样自然生长。

The result was a qualified success.
结果相当成功。

First and foremost, neither patient had an adverse reaction to the transplant always a risk when foreign tissue is put into someone's body.
首先，也是最重要的是，两位病患都没有对新移植的细胞产生排斥－这是移植异体组织常常要面临的风险。

Second, though neither had vision restored to any huge degree, each was able, four months after the transplant,
其次，虽然两名患者的视力没有很大程度的恢复，但移植4个月后，

to distinguish more letters of the alphabet than they could beforehand.
与患病前相比，他们都能识别出更多视力表上的字母了。

Whether Dr Schwartz's technique will prove truly useful remains to be seen. Experimental treatments fail far more often than they succeed.
但现在就确定的说Dr Schwartz的技术很实用还为时尚早，失败的试验远比成功的案例更多。

But the second paper, published in Nature by Lawrence Goldstein of the University of California, San Diego, and his colleagues,
但由圣迭戈加州大学的 Lawrence Goldstein及其同事发表在《自然》杂志的这篇论文，

shows how stem cells can be of use even if they do not lead directly to treatment.
也是我想说的第二篇论文，就能看出干细胞尽管还不能直接用于治疗，但已经相当“好使”了。

Since 2006 researchers have been able to reprogram adult cells into an embryonic state, using proteins called transcription factors.
自从2006年以来，研究人员已经能用一种称为转录因子的蛋白质分子将体细胞诱导成为类似胚胎细胞的干细胞，

Though these reprogrammed cells, known as induced pluripotent stem cells, might one day be used for treatment,
尽管这种诱导多潜能干细胞迟早会有一天能在再生医疗领域大展拳脚，

their immediate value is that they are also an excellent way to understand illness.
但眼下，它们的价值则体现在对疾病的研究上，这是个很好的方法。

Using them, it is possible to make pure cultures of types of cells that have gone wrong in a body.
利用它们就能离体培养出与体内患病组织相同类型的细胞来。

Crucially, the cultured cells are genetically identical to the diseased ones in the patient.
关键是，这些培养出的细胞与患者的染病细胞在基因组成上是相同的。

Dr Goldstein is therefore using iPS cells to try to understand Alzheimer's disease.
因此,Dr Goldstein将用iPS来揭开阿尔茨海默症的病因。

The brains of those with advanced Alzheimer's are characterised by deposits,
重症阿尔茨海默病患者的大脑内明显特征是,有一种称为淀粉样蛋白碎片的积淀物，

known as plaques, of a protein-fragment called beta-amyloid, and by tangles of a second protein, called tau.
也是我们所称的斑块，与另一种蛋白的结团物。

But how these plaques and tangles are related remains unclear.
但这些斑块和结团是何种关系还不明确。

To learn more, Dr Goldstein took tissue from six people:
为了深入研究， Dr Goldstein从6位病患身上取了组织：

two with familial Alzheimer's, a rare form caused by a known genetic mutation;
2位是家族阿尔茨海默病患者－因较罕见的基因突变所引发的；

two with sporadic Alzheimer's, whose direct cause is unknown; and two unaffected individuals who acted as controls.
2位是散发性阿尔茨海默病患者－致病原因不详；2位是行动可控的未患病者。

He reprogrammed the cells collected into iPS cells, then nudged them to become nerve cells.
先将收集的体细胞诱导成iPS,再用这些iPS细胞转化神经细胞。

In three of the four Alzheimer's patients these lab-made nerve cells did,
4位阿尔茨海默病患者中，3位的实验获得神经细胞中，表现出高水平的淀粉样蛋白和蛋白，

indeed, show higher levels of beta-amyloid and tau and also of another characteristic of the disease, an enzyme called active GSK3-beta.
并且，与此疾病相关的另一特征：一种称为GSK3活性酶的水平也较高。

Since he now had the cells in culture, Dr Goldstein could investigate the relationship between the three.
于是，他将这三种神经细胞植入培养皿中培养，以发现三者之间的关系。

To do so he treated the cultured cells with drugs.
之后，他就能用药物来处理培养出的细胞。

He found that a drug which attacked beta-amyloid directly did not lead to lower levels of tau or active GSK3-beta;
他发现用药物直接处理淀粉样蛋白并不能致使Tau蛋白和GSK3活性酶的水平降低；

but a drug which attacked one of beta-amyloid's precursor molecules did have that effect.
但如果用药物处理淀粉样蛋白的前体分子，效果就会很好。

That is useful information, for it suggests where a pharmacological assault on the disease might best be directed.
这是很有价值的信息，能判断在哪里用药才能直达病灶。

In the short term, at least, iPS-based studies of this sort are likely to yield more scientific value than clinical experiments of the type conducted by Dr Schwartz,
在短期内，此类基于iPS的研究在科学价值方面的意义远大于Dr Schwartz进行的临床实验结果，

even though they are not treatments in themselves.
因为他们的研究本身还不能用于治疗病患。

That will, though, require many more pluripotent cells.
不过，对多潜能干细胞的需求会与日俱增，

And at least one firm is selling a way to make billions of iPS cells for just that purpose.
至少有一家公司会源源不断的提供数十亿的iPS细胞用于此类研究，

Its founder, appropriately, is Dr Thomson.
它的创始人正是Thomson.