细胞“返老还童”技术获重大突破

naturalkillerce

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细胞“返老还童”技术获重大突破' c5 B  D* E. e0 Q1 X! Q* S. s3 {
来源： 新华国际 2011年11月02日

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+ L* N& {. C5 j3 b/ \. }  T: R显微镜下的胚胎干细胞

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% u6 T7 j9 y0 w" F7 V为再生医学开新路& A" b- {8 t) y( A+ X" i

, ^5 e- ]& T: j. W: K! r    【法新社巴黎10月31日电】科学家们今天说，他们已将90岁以上的老人———包括一名百岁老人———体内历经岁月磨损的细胞转化为重新恢复活力、与胚胎中的干细胞“难以区分”的干细胞。
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    研究人员说，发表在《基因与发育》半月刊上的这一技术成果为再生医学开辟了一条新路，尤其是对老人而言。
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' E# m1 @9 b5 M# ^# Q- }    法国蒙彼利埃大学功能基因组学研究所的研究员、这项研究的带头人让-马克·勒迈特说：“这是细胞新生的一种新形式。”7 D1 i: l" j& I) W

4 ]. N$ y6 U3 i- Z    他在电话中对本社记者说：“细胞的年龄绝对不是重编程的障碍。”; P( e# N6 ^5 H2 H' c, I9 f5 G

/ k4 l& L" p# Y/ y6 j: _" m" B6 Q    人类胚胎干细胞能够成为人体内任何种类的细胞这一事实让人们长期以来怀着以下这个希望：用健康的、在实验室中培育出来的细胞修复或取代生病的器官或组织。但事实证明，从理论跨越到实践是困难的，人们充满伦理和道德方面的担心，因为这样做需要摧毁一个人类胚胎。
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    2007年，有人发现，可能使某些成体细胞回到不成熟的、特化前的状态。
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    这一发现使人们重新开始为培植全新的肌肉、心脏甚至脑细胞而努力，而且这一次是通过患者提供的原材料。# h/ d0 T& [* G5 z" H
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    然而，迄今为止的实验表明，通常使用的培植这些所谓的诱导多能干细胞的化学方法在老人以及高龄老人身上效果不太好，或者完全无效。而恰恰是这些人可以从再生医学中获益最多。% X5 p! b+ S6 ^1 R0 F
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    障碍是细胞衰老，这个与老化有联系的自然过程能够导致细胞因其内部某些机制变得过于退化而无法正常运转从而死亡。1 M, }# M+ z; I. b
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    勒迈特及其同事决定改变通常用来培植成体干细胞的方法，加入两种被称为转录因子的新成分，即NANOG和LIN28。! y9 V' n3 ]& H7 }2 ?# K

! F, X; Y% `& p, O2 [# S2 E( w    对年龄从74岁到101岁不等的老人进行的实验显示，新方法有效。
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- s1 @$ e$ d9 }# h    研究人员称，细胞内某些标志着老化的关键标记“重启”了，包括端粒的大小。端粒是位于染色体两端起保护作用的微小帽状物，随年龄增长而变小。端粒和端粒酶是决定寿命长短的关键因素。细胞每分裂一次，端粒就变小一些。端粒酶的作用是部分复制端粒。最终，当端粒变得不可修复，细胞就死亡了。
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5 K8 n  f4 F3 p! Z$ D; `    研究发现，基因表达谱、氧化应激程度以及细胞中产生能量的线粒体的新陈代谢类似地都得到了新生。

sunsong7

下面文章从微环境角度研究得到类似结论，但是老龄干细胞的遗传稳定性是困扰其应用的障碍。1 {7 u$ n9 ^+ l8 G  j8 z8 o4 e
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Personal Stem Cell Banks Could Be Staple of Future Health Care

9 Z1 B5 E# Q# rScienceDaily (Nov. 1, 2011) — Old stem cells can be rejuvenated by being placed in a young microenvironment, research from The University of Texas Health Science Center San Antonio shows. This raises the possibility that patients' own stem cells may one day be rescued and banked to treat their age-related diseases.% S) X5 j' a. V- k) r! l
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3 C: }' I: S% FStem cells are immature cells that have the potential to convert into bone, muscle, blood vessels, nerve fibers, and other body cells and tissues. It's no wonder medical science seeks to utilize these versatile cells to restore tissues deteriorated by age, disease or injury.0 M" D2 W* C( F4 w
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Older stem cells are not as robust as young ones, however -- a challenge to clinicians who seek to use patients' own stem cells to treat age-related diseases." l( w( x$ Z7 A0 O) \
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"The number and quality of those cells decline with age, that is very clear," said Xiao-Dong Chen, M.D., Ph.D., a stem cell researcher at the UT Health Science Center. "And, using the patient's own cells can impact results."
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' C  j6 o1 ?* x/ gDr. Chen's team recently made a discovery in mice that, if translated to humans, could solve this predicament.8 Y" z! F' N( d* @7 I

: x/ A0 x- l/ ~Old cells expand when grown on a young scaffold of tissue9 V5 L: j4 J- l

1 w; S; y# g; k/ y# K6 _Dr. Chen suspected that giving stem cells a youthful environment for growth would cause them to regenerate faster. His team extracted mesenchymal stem cells from the bone marrow of 3-month-old mice and 18-month-old mice. The group also obtained extracellular matrix (ECM) from mice of both ages. ECM is a scaffold of connective tissue, such as collagen, which constitutes a majority of the body's structure.6 I! c! @1 V' P
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The lab team seeded half of the older stem cells on ECM from the 3-month-old mice and half on ECM from the 18-month-old mice. Likewise, half of the young stem cells were seeded on the young ECM and half were seeded on the old ECM.
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- N5 ]; c6 O; x# [6 A! O; B5 I; q8 oYoung and old cells showed a 16.1-fold and 17.1-fold expansion, respectively, when grown on ECM from young mice, compared to a 4.1-fold and 3.8-fold expansion when grown on ECM from old mice.
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Finding confirmed in rodent implants
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Next, under the skin of mice, Dr. Chen's group implanted artificial scaffolds seeded with stem cells of both ages that had been grown on young or old ECM. These were left to grow for eight weeks. The researchers targeted bone formation. When the implants were removed, the team found that old cells that had been grown on a young ECM produced just as much bone as young cells, while old cells grown on an old ECM produced no bone. The results were published in the FASEB Journal earlier this year.
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% Y$ n+ b0 V- X"If this research transfers successfully to clinical application in humans, we could establish personal stem cell banks," Dr. Chen said. "We would collect a small number of older stem cells from patients, put those into our young microenvironment to rescue them -- increasing their number and quality -- then deliver them back into the patient."5 z( s$ |4 ^+ ]; k

5 n* C2 v- Z* Z7 gThis stem cell rescue and infusion could be done as often as disease treatment requires it, he said. The next step is to repeat the study in human stem cells and ECM.- f7 v* p  P6 M: G( P+ |
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fwyou

不是paper 是个new

tjbone

学习谢谢了！！！！！！！

subenjinwo

不错呢。

xuetian

就是说：如果端粒酶一直数量不减活力不减，生命就可以久久不衰？

wangzhiqi86

够猛

naturalkillerce

回复 xuetian 的帖子+ C9 W' i- G: I- w6 E
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要知道，癌症细胞的端粒长度就不会缩短。就算生命可以永生，端粒酶保有活性确保端粒长度不缩短，也只是其中的一个特征而已。

lianzhimin

回复 xuetian 的帖子# R. T+ u  y  [8 T/ E: l8 F4 L

5 N2 W! p' E# I9 W经久不衰的可以存在，但不是生命了。原因：生命属于自然，自然的永恒源于在平衡中不断的更新变化延续。端粒只是人类细胞寿命的一个标识，楼上也有说癌细胞中端粒酶高表达，所以单纯的增加端粒的长度并非是延长寿命的良策，也许会引发癌变。另外，端粒对细胞存活，凋亡的影响程度有多大，有多关键还未可知。要知道，老鼠中所有细胞都高表达端粒酶，也就是说端粒在不同种类动物中作用是不同的，对高等脊椎动物细胞寿命年龄的指示作用和对凋亡增殖通路的影响可能是端粒后期进化发育的结果。呵呵，私以为的观点，还请多多指教！