干細(xì)胞是尚未分化成熟的細(xì)胞，除胚胎干細(xì)胞外,，多數(shù)干細(xì)胞常常“命中注定”只能成長為某一種特定的細(xì)胞,。但刊登在19日出版的英國《自然》雜志上的一項(xiàng)最新研究成果顯示，只要改變成長環(huán)境,，來自胸腺的干細(xì)胞也可以“轉(zhuǎn)行”變?yōu)槊壹?xì)胞,。這對于研究器官組織再生具有重要意義。
據(jù)英國愛丁堡大學(xué)發(fā)布的公告,，該校研究人員和瑞士同行進(jìn)行的這項(xiàng)研究成功改變了實(shí)驗(yàn)鼠胸腺干細(xì)胞的“命運(yùn)”,。胸腺是存在于人和許多動(dòng)物胸部的一個(gè)器官，它是免疫細(xì)胞T細(xì)胞的生成地,，在免疫系統(tǒng)中發(fā)揮著重要作用,。
研究人員首先培養(yǎng)出實(shí)驗(yàn)鼠胸腺干細(xì)胞，然后將它轉(zhuǎn)移到適宜皮膚毛囊細(xì)胞生長的環(huán)境中培養(yǎng),，結(jié)果發(fā)現(xiàn)這些胸腺干細(xì)胞在新環(huán)境中逐漸改變了自己的基因特征,，越來越像皮膚毛囊的干細(xì)胞。
在這種環(huán)境中培育一段時(shí)間后,，這些細(xì)胞被移植到正在生長的皮膚中,，結(jié)果它們擁有了像毛囊細(xì)胞一樣供養(yǎng)和修復(fù)毛發(fā)的能力，且表現(xiàn)出色,。天然毛囊干細(xì)胞成長后只有三個(gè)星期的修復(fù)毛發(fā)能力,，而這些胸腺干細(xì)胞“轉(zhuǎn)行”后擁有長達(dá)一年的修復(fù)毛發(fā)能力。
據(jù)介紹,，大部分動(dòng)物的胚胎分為外胚層,、中胚層和內(nèi)胚層三個(gè)胚層,，外胚層成長為皮膚和神經(jīng)等，中胚層成長為肌肉,、骨骼和血液等,，內(nèi)胚層成長為腸道、肝臟和胸腺等器官,。過去一直認(rèn)為這三個(gè)胚層的細(xì)胞間存在無法逾越的鴻溝,，但本次研究證明來自內(nèi)胚層的胸腺干細(xì)胞也可以變?yōu)楸緫?yīng)屬于外胚層的皮膚毛囊細(xì)胞，顯示不同胚層細(xì)胞間的區(qū)分并不絕對,。
愛丁堡大學(xué)的克萊爾·布萊克本博士說,，這些胸腺干細(xì)胞在適宜毛囊干細(xì)胞成長的環(huán)境里完全改變了原定的成長軌道,，從而啟發(fā)研究人員使用適宜其他器官干細(xì)胞成長的環(huán)境,，探索能否培育出所需的器官細(xì)胞，這對研究器官組織再生具有重要意義,。（生物谷Bioon.com）
生物谷推薦原文出處：
Nature doi:10.1038/nature09269
Microenvironmental reprogramming of thymic epithelial cells to skin multipotent stem cells
Paola Bonfanti,Stéphanie Claudinot,Alessandro W. Amici,Alison Farley,C. Clare Blackburn& Yann Barrandon
The thymus develops from the third pharyngeal pouch of the anterior gut and provides the necessary environment for thymopoiesis (the process by which thymocytes differentiate into mature T lymphocytes) and the establishment and maintenance of self-tolerance1, 2, 3. It contains thymic epithelial cells (TECs) that form a complex three-dimensional network organized in cortical and medullary compartments, the organization of which is notably different from simple or stratified epithelia4. TECs have an essential role in the generation of self-tolerant thymocytes through expression of the autoimmune regulator Aire5, 6, but the mechanisms involved in the specification and maintenance of TECs remain unclear7, 8, 9. Despite the different embryological origins of thymus and skin (endodermal and ectodermal, respectively), some cells of the thymic medulla express stratified-epithelium markers10, 11, 12, interpreted as promiscuous gene expression. Here we show that the thymus of the rat contains a population of clonogenic TECs that can be extensively cultured while conserving the capacity to integrate in a thymic epithelial network and to express major histocompatibility complex class II (MHC II) molecules and Aire. These cells can irreversibly adopt the fate of hair follicle multipotent stem cells when exposed to an inductive skin microenvironment; this change in fate is correlated with robust changes in gene expression. Hence, microenvironmental cues are sufficient here to re-direct epithelial cell fate, allowing crossing of primitive germ layer boundaries and an increase in potency13.
