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[灌水交流] 返老还童药之研究进展

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发表于 2010-11-30 17:32:35 |显示全部楼层
本帖最后由 如获志保 于 2010-11-30 17:33 编辑

新闻链接:http://www.nature.com/news/2010/101128/full/news.2010.635.html
文献链接:http://www.nature.com/nature/journal/vaop/ncurrent/full/nature09603.html
Telomerase reverses ageing process
Dramatic rejuvenation of prematurely aged mice hints at potential therapy.
Ewen Callaway

Protecting chromosome tips doesn't just prevent ageing. It can reverse it.
Peter Lansdorp/Visuals Unlimited/Corbis

Premature ageing can be reversed by reactivating an enzyme that protects the tips of chromosomes, a study in mice suggests.

Mice engineered to lack the enzyme, called telomerase, become prematurely decrepit. But they bounced back to health when the enzyme was replaced. The finding, published online today in Nature1, hints that some disorders characterized by early ageing could be treated by boosting telomerase activity.


It also offers the possibility that normal human ageing could be slowed by reawakening the enzyme in cells where it has stopped working, says Ronald DePinho, a cancer geneticist at the Dana-Farber Cancer Institute and Harvard Medical School in Boston, Massachusetts, who led the new study. "This has implications for thinking about telomerase as a serious anti-ageing intervention."


Other scientists, however, point out that mice lacking telomerase are a poor stand-in for the normal ageing process. Moreover, ramping up telomerase in humans could potentially encourage the growth of tumours.


Eternal youth

After its discovery in the 1980s, telomerase gained a reputation as a fountain of youth. Chromosomes have caps of repetitive DNA called telomeres at their ends. Every time cells divide, their telomeres shorten, which eventually prompts them to stop dividing and die. Telomerase prevents this decline in some kinds of cells, including stem cells, by lengthening telomeres, and the hope was that activating the enzyme could slow cellular ageing.


Two decades on, researchers are realizing that telomerase's role in ageing is far more nuanced than first thought. Some studies have uncovered an association between short telomeres and early death, whereas others have failed to back up this link. People with rare diseases characterized by shortened telomeres or telomerase mutations seem to age prematurely, although some tissues are more affected than others.


When mice are engineered to lack telomerase completely, their telomeres progressively shorten over several generations. These animals age much faster than normal mice — they are barely fertile and suffer from age-related conditions such as osteoporosis, diabetes and neurodegeneration. They also die young. "If you look at all those data together, you walk away with the idea that the loss of telomerase could be a very important instigator of the ageing process," says DePinho.


To find out if these dramatic effects are reversible, DePinho's team engineered mice such that the inactivated telomerase could be switched back on by feeding the mice a chemical called 4-OHT. The researchers allowed the mice to grow to adulthood without the enzyme, then reactivated it for a month. They assessed the health of the mice another month later.


"What really caught us by surprise was the dramatic reversal of the effects we saw in these animals," says DePinho. He describes the outcome as "a near 'Ponce de Leon' effect" — a reference to the Spanish explorer Juan Ponce de Leon, who went in search of the mythical Fountain of Youth. Shrivelled testes grew back to normal and the animals regained their fertility. Other organs, such as the spleen, liver and intestines, recuperated from their degenerated state.


The one-month pulse of telomerase also reversed effects of ageing in the brain. Mice with restored telomerase activity had noticeably larger brains than animals still lacking the enzyme, and neural progenitor cells, which produce new neurons and supporting brain cells, started working again.


"It gives us a sense that there's a point of return for age-associated disorders," says DePinho. Drugs that ramp up telomerase activity are worth pursuing as a potential treatment for rare disorders characterized by premature ageing, he says, and perhaps even for more common age-related conditions.


Cancer link

The downside is that telomerase is often mutated in human cancers, and seems to help existing tumours grow faster. But DePinho argues that telomerase should prevent healthy cells from becoming cancerous in the first place by preventing DNA damage.


David Sinclair, a molecular biologist at Harvard Medical School in Boston, agrees there is evidence that activating telomerase might prevent tumours. If the treatment can be made safe, he adds, "it could lead to breakthroughs in restoring organ function in the elderly and treating a variety of diseases of aging."


Other researchers are less confident that telomerase can be safely harnessed. "Telomere rejuvenation is potentially very dangerous unless you make sure that it does not stimulate cancer," says David Harrison, who researches ageing at the Jackson Laboratory in Bar Harbor, Maine.


Harrison also questions whether mice lacking telomerase are a good model for human ageing. "They are not studying normal ageing, but ageing in mice made grossly abnormal," he says. Tom Kirkwood, who directs the Institute for Ageing and Health at Newcastle University, UK, agrees, pointing out that telomere erosion "is surely not the only, or even dominant, cause" of ageing in humans.


DePinho says he recognizes that there is more to ageing than shortened telomeres, particularly late in life, but argues that telomerase therapy could one day be combined with other therapies that target the biochemical pathways of ageing. "This may be one of several things you need to do in order to extend lifespan and extend healthy living," he says.




相关中文报导:

  北京时间11月30日消息,美国科学家最近通过老鼠试验,第一次成功逆转了衰老过程,这为研制出“永葆青春”的药物铺平了道路。这项研究由美国哈佛大学的肿瘤医生罗纳德·德宾霍进行,相关科研成果发表在权威学术期刊《自然》杂志上。

  在进行试验以前,这些动物的皮肤、大脑、内脏和其他器官与80岁老人的类似。给它们服用可以打开一种关键性酶的药物仅2个月后,这些动物长出大量新细胞,它们几乎是经过彻底更新,已经返老还童了。更令人吃惊的是,公鼠竟能令母鼠再度怀孕,养育大量后代。

  如果借助这项研究,科学家研制出“永葆青春”的药物,人们就能更长寿、更健康、不会受到老年痴呆症和心脏病的困扰,皮肤和头发会像年轻时一样光泽亮 丽。这种药物或许还能令男性和女性在高龄以前一直能够自然生育小孩。增加健康生活的时间还可以大大减少卫生服务成本、减轻家人照顾体弱多病的亲戚的负担。

  德宾霍说:“这就如同一个40岁的人看起来像80岁,经过逆转后使他达到50岁的水平。到2025年我们将有12亿年龄超过60岁的老人,这个年龄段的人开始易患癌症、老年痴呆症和心血管疾病。我们即将面临繁重的社会负担。这项试验是我们首次成功逆转衰老过程。这说明有一个逆转衰老器官的要点是我们以前从没意识到的。”

  这项重大突破主要着眼于端粒结构。这些是覆盖在染色体末端,防止它们受损的微型生物钟。随着时间推移,端粒变得越来越短,这增加了患老年痴呆症等老年疾病的风险。等到它们变得太短,整个细胞就会死亡。端粒酶逆转录酶能再造端粒,但是身体往往会把这种酶关掉。

  德宾霍通过特殊方法使老鼠提前衰老,以模拟人类的衰老过程,然后利用药物刺激,成功令端粒酶逆转录酶重新恢复生机。他希望这一技术能终止或放慢衰老过程,发现它和逆转它是件令人吃惊的事情。他认为,最终应该能研制出一种可以在人类身上产生相同效果的药物。就拿中年人来说,这种药物能延缓或防止他们患老年痴呆症、心脏病和糖尿病,甚至可延长寿命。

  不过人们也要注意:高水平端粒酶逆转录酶可加速肿瘤生长,单凭一种药物不可能清除所有衰老问题。德宾霍说:“衰老是由多种机制共同造成的。因此,虽然我们认为端粒非常重要,但是还有其他因素也在发挥重要作用。”美国哈佛大学的端粒专家史蒂文·亚坦迪博士称这项研究“非常漂亮”,但是他警告说,一种抗衰老药物最多只能逆转10多年时间。

  (来源:新浪科技)
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平和联盟勋章 边缘联盟勋章

发表于 2010-11-30 17:39:02 |显示全部楼层
返老还童药是不可能有的,至少我相信我是看不到类似APTX4869的药了
阿森纳看台散场后有一对父子,儿子还很小,走着走着仰起头来问父亲:“Dad, are you sad?”
父亲抱起儿子,说道:“Yes, I'm sad. But we can't leave Arsenal alone when they're sad, right?”
男孩点点头:“We NEVER!”
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发表于 2010-11-30 17:48:52 |显示全部楼层
退行到幼年当然不可能~但是对于成年人的抗衰老药是必然会出现的~
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平和联盟勋章 边缘联盟勋章

发表于 2010-11-30 18:22:35 |显示全部楼层
那就是抗衰老药,不是返老还童药=v=
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发表于 2010-11-30 19:18:25 |显示全部楼层
那就是说返老可以,还童还差点儿咯?嘻嘻嘻
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发表于 2010-11-30 19:31:31 |显示全部楼层
返老还童不过是个修辞罢了~你看熊德给DH套个返老还童也没见DH变成婴儿啊~没人指望返老还童是变回小孩子的~回到精壮青年时代才是目标~当小孩子玩儿啥啥不灵不是自虐么= =
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发表于 2010-11-30 20:03:38 |显示全部楼层
只能逆转10多年。。
还是等到发明了再来说吧 = = 这科技越发展越可怕~
______
不是因为真的才相信
而是因为相信才会变成真的。
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发表于 2010-11-30 21:00:07 |显示全部楼层
额。。几天不上网居然就看到如此让人吃惊的东西
天使有时候扮演着一个麻木着人的神经的角色
恶魔虽然邪恶但是让人们学会接受血琳琳的现实
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发表于 2010-11-30 21:18:58 |显示全部楼层
先熬过2012吧。。。
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