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作者：Cheng-Ming Chuong 来源：《科学》 发布时间：2011-5-17
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美国每日科学网站5月15日报道：美国南加利福尼亚大学凯克医学院的科学家们破译了老鼠和兔子的毛发干细胞之间是如何交流并以相互协调的方式促进再生的。这是人类首次关注成千上万个毛囊中的干细胞群的群体行为，此前的研究只是关注单个毛囊中的干细胞。
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这个团队与来自英国牛津大学的数学生物学家合作，对剃毛老鼠和兔子在数月里毛发生长模式的变化进行了分析。毛发生长模式的变化说明了毛囊中干细胞在活跃和休眠状态之间的周期性发展。相关论文发表于4月29日的《科学》（Science）杂志。( o2 ]+ C( M/ j8 _9 ]0 B4 e( t& t
% b( G$ [' q; ^% W& s凯克医学院病理学教授、这项研究的首席科学家钟正明说：“结果完全出人意料。这其中存在着肉眼看不到的复杂协调过程。”该研究由美国国家卫生研究院资助。4 F( r" z2 u. F3 s/ d I* x/ y
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钟正明所说的“复杂协调过程”指大型毛发干细胞群内部为了使毛发健康生长而进行的相互交流的过程。这使得毛发的波纹形状出现持续变化，从外表上看经常像是在兔子的皮肤上“画”了一幅抽象画。
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科学家发现，毛发干细胞之间在分子催化剂WNT和抑制剂BMP的帮助下就它们的再生进行协调。当WNT和BM P的信号在整个皮肤表面由成千上万个毛囊组成的群内部被反复利用时，毛发便通过自组织过程呈现出复杂的再生行为。* G: ~3 M5 u' z' p# Z9 f
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这项研究可能会使人们通过改善交流环境找到治疗脱发症的方法。人类之所以会患上脱发症，部分原因在于，与老鼠和兔子不同，人类毛囊中的干细胞已经丧失了相互交流的能力。
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钟正明说：“当人类的某个毛囊细胞想要再生时，它只能依靠自身，得不到其他毛囊的帮助。然而，当兔子的毛囊再生时，它可以依靠来自两方面的力量：一是自身的活化作用，二是来自周边毛囊的活化信号。兔子的毛发生长非常积极，这对它们在野外生存是至关重要的。”) T6 d$ f/ _; f/ y
' I$ _( J9 Z+ L3 V这份研究报告的主要作者、美国宾夕法尼亚大学的博士后马克西姆·普利克斯说，如果可以唤醒人类干细胞的“交流”机制，那么便有可能使处于生长期的人类头发大大增加。: J! V8 u9 j8 w; i Q6 B5 ]
$ _ i7 p2 D1 _9 O3 e: G6 h: l这个研究结果具有非常好的前景，南加利福尼亚大学史蒂文斯创新研究所已经将其应用在一名脱发患者身上。（来源：新华网） 3 K( T' D$ P" b6 |1 m
Potential for Solution to Baldness? Surprising Clues About Communication in Hair Stem Cell Populations
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ScienceDaily (May 15, 2011) — In one of the first studies to look at the population behavior of a large pool of stem cells in thousands of hair follicles -- as opposed to the stem cell of a single hair follicle -- Keck School of Medicine of USC scientists deciphered how hair stem cells in mice and rabbits can communicate with each other and encourage mutually coordinated regeneration, according to an article published in the April 29 edition of the journal Science.
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. D! H+ p1 X* a* tThe team, which collaborated with mathematical biologists from the University of Oxford, analyzed over many months the changes in the hair growth patterns on shaved mice and rabbits, which indicate cyclic progression between active and quiescent states by stem cells in hair follicles.
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% K6 A" r- P6 V6 P% W, g"The results are totally surprising. There is complex coordination not apparent to the naked eye," said Cheng-Ming Chuong, professor of pathology at the Keck School and the principal investigator of the study funded by the National Institutes of Health.
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8 h! Q- J; c9 ZThe "complex coordination" Chuong refers to is the ability of the large hair stem cell population to communicate with each other to reach robust hair growth, manifesting in a constantly shifting hair wave pattern that often looked like a piece of abstract artwork "painted" on the rabbit's skin.. s1 {$ n; A8 T$ }( t: B
! c, b) K$ i& C$ Z) ?# uThe scientists found that hair stem cells coordinate their regeneration with each other with the aid of a pair of molecular activator WNT and inhibitor BMP. When WNT and BMP signals are used repetitively among a population of thousands of hair follicles across the entire skin surface, complex regenerative hair growth behavior emerges via the process of self-organization.
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u/ }' `) u1 rThe research holds potential for finding a cure for alopecia, or hair loss, by improving the environment for communication. Alopecia occurs in humans partially because stem cells in human hair follicles, unlike those in mice and rabbits, have lost the ability to communicate with each other.
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"When each human hair follicle wants to regenerate, it can only count on itself; it's not getting help from other follicles," Chuong said. "But when a rabbit hair follicle regenerates, it can count on two inputs: its own activation, and the activation signal from its neighbors. Rabbits have a very active hair growth, and that is essential for their survival in the wild."
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- W+ i. |8 W0 n9 n- ~7 eIf the mechanism of stem cell "communication" can be awakened in human stem cells, it will be possible to significantly increase the proportion of human hairs in a growing phase, said Maksim Plikus, the paper's lead author, now a postdoctoral research associate at the University of Pennsylvania. While conducting the study Plikus was with the Keck School and was supported by the postdoctoral training grant from California Institute for Regenerative Medicine.
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1 m. Z& l* G5 U/ M- e Y7 t1 ?The study's results are promising enough that the USC Stevens Institute for Innovation has already applied for a patent on the composition and method to modulate hair growth.
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4 L' y- [( S D! |" v7 x2 IThe findings also provide insight into potential stem cell behavior in other organs, which holds ramifications for regenerative medicine research. The fact that a large population of a rabbit's hair stem cells can encourage each other to regenerate and to take turns resting implies it may be possible for other organs' stem cells -- including in humans -- to similarly communicate and spur growth with high efficiency.
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"This work should stimulate the search for similar population-level behaviors among stem cells in other key regenerative systems, such as the gastro-intestinal tract and bone marrow," Plikus said.
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The study builds upon an earlier paper that a team led by Plikus and Chuong published three years ago in the journal Nature. That study looked at the hair growth patterns on mice and found that the macro-environment, which includes subcutaneous adipose tissue and body hormone changes, could influence the regenerative behavior of individual hair follicles. It also found new functionally distinct, but morphologically indistinguishable phases in a hair follicle's growing and resting stages. p3 ^4 Z x' W2 y% @/ ~
# w+ @4 \$ O N5 c4 [4 T"Combined together, our 2008 Nature and 2011 Science papers push our understanding of the regenerative processes in an adult organ to a new level," Plikus said.# n* t- | e6 ]9 |" c: t
- D' B3 ?! D7 E* \# XChih-Chiang Chen, Damon de la Cruz and Randall Widelitz of the Keck School's department of pathology were also authors on the study.& @. s% j8 T5 [$ z0 U6 ~. M% ~: y: @
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发表于 2011-5-17 18:26
发表于 2011-5-18 22:28
