美國干細(xì)胞科學(xué)家的一項(xiàng)最新研究，找到了培育人類胚胎干細(xì)胞（hESC）的新方法,。相關(guān)論文8月20日發(fā)表在《公共科學(xué)圖書館 綜合》（PLoS ONE）上,。
大多數(shù)研究人員都是利用來自動(dòng)物的原材料來培育人類胚胎干細(xì)胞。但這樣做有可能將病毒和其他一些病原體傳播到培育出的干細(xì)胞中,，導(dǎo)致它們無法在醫(yī)學(xué)治療上使用,。對此，美國加州大學(xué)河畔分校的生物化學(xué)副教授Noboru Sato和同事開發(fā)出一種新的培育方法,，比傳統(tǒng)手段更加清潔,、方便，而且得到的胚胎干細(xì)胞具有不打折扣的多能性,。
目前,，全世界實(shí)驗(yàn)室中常用涂有Matrigel（一種從小鼠腫瘤細(xì)胞中提取出的凝膠，包含細(xì)胞外基質(zhì)ECMs）的培養(yǎng)皿來培育人類胚胎干細(xì)胞,。Matrigel涂層為干細(xì)胞的培養(yǎng)提供了支架,，當(dāng)少量的人類胚胎干細(xì)胞附著其上后，會(huì)生長為未分化細(xì)胞集落,。
Sato解釋說,，“鑒于ECM的復(fù)雜性以及人們對hESC如何控制細(xì)胞間和細(xì)胞-ECM相互作用的認(rèn)識不足，要開發(fā)出非動(dòng)物（animal-free）涂層的培養(yǎng)方法仍是一大挑戰(zhàn),。”
在最新的研究中,，Sato小組鑒別出一個(gè)特殊的信號路徑——Rho-Rock，它對細(xì)胞集落形成和hESC間物理相互作用起重要作用,。當(dāng)該信號路經(jīng)被名為Y27632的物質(zhì)阻斷后,，研究人員發(fā)現(xiàn),，正如預(yù)期的那樣，hESC正常的集落形成被大大削弱,。而研究人員同時(shí)注意到,，hESC仍然保持著它們的多能性。
Sato說,，“到目前為止,，人們通常認(rèn)為集落形成是維持胚胎干細(xì)胞多能性的關(guān)鍵，但我們的研究發(fā)現(xiàn),，多能性可以獨(dú)立于緊密地細(xì)胞間聯(lián)系而被保留下來,。”
除此之外，研究人員還廣泛篩選了可與Y27632結(jié)合的多種類型的支架材料,，結(jié)果發(fā)現(xiàn),，Matrigel涂層可以被另一種物質(zhì)poly-D-lysine取代。后者最主要的優(yōu)點(diǎn)就是完全非動(dòng)物的,，容易操控而且質(zhì)量穩(wěn)定,。同時(shí)，poly-D-lysine涂層與傳統(tǒng)的Matrigel相比,，培養(yǎng)得到的人類胚胎干細(xì)胞的多能性幾乎沒有差別,。
加州大學(xué)河畔分校干細(xì)胞中心主任Prue Talbot表示，“Sato的工作無論對理解干細(xì)胞信號轉(zhuǎn)導(dǎo)路徑還是開發(fā)出改進(jìn)的干細(xì)胞培育方法,，都的確是重要的一步,。”
據(jù)悉，研究人員目前正在嘗試將新技術(shù)應(yīng)用于最新的干細(xì)胞技術(shù)——誘導(dǎo)多能干細(xì)胞（iPS）,。Sato說,，“我們的下一個(gè)目標(biāo)就是制造新的非動(dòng)物iPS細(xì)胞系。”（生物谷Bioon.com）
生物谷推薦原始出處：
PLoS ONE,，3(8): e3001. doi:10.1371/journal.pone.0003001,，Nicole Harb, Trevor K. Archer, Noboru Sato
The Rho-Rock-Myosin Signaling Axis Determines Cell-Cell Integrity of Self-Renewing Pluripotent Stem Cells
Nicole Harb1, Trevor K. Archer2, Noboru Sato1*
1 Department of Biochemistry, University of California Riverside, Riverside, California, United States of America, 2 Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, United States of America
Abstract
Background
Embryonic stem (ES) cells self-renew as coherent colonies in which cells maintain tight cell-cell contact. Although intercellular communications are essential to establish the basis of cell-specific identity, molecular mechanisms underlying intrinsic cell-cell interactions in ES cells at the signaling level remain underexplored.
Methodology/Principal Findings
Here we show that endogenous Rho signaling is required for the maintenance of cell-cell contacts in ES cells. siRNA-mediated loss of function experiments demonstrated that Rock, a major effector kinase downstream of Rho, played a key role in the formation of cell-cell junctional assemblies through regulation of myosin II by controlling a myosin light chain phosphatase. Chemical engineering of this signaling axis by a Rock-specific inhibitor revealed that cell-cell adhesion was reversibly controllable and dispensable for self-renewal of mouse ES cells as confirmed by chimera assay. Furthermore, a novel culture system combining a single synthetic matrix, defined medium, and the Rock inhibitor fully warranted human ES cell self-renewal independent of animal-derived matrices, tight cell contacts, or fibroblastic niche-forming cells as determined by teratoma formation assay.
Conclusions/Significance
These findings demonstrate an essential role of the Rho-Rock-Myosin signaling axis for the regulation of basic cell-cell communications in both mouse and human ES cells, and would contribute to advance in medically compatible xeno-free environments for human pluripotent stem cells.
