干細胞技術已能制造出小型人類肝臟

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【英國廣播公司網站10月30日報道】科學家們設法利用干細胞在實驗室制造出小型人類肝臟。
這一成功增加了制造出可用于移植的新肝臟的希望，盡管專家們說這還需要很多年時間。
來自美國韋克福雷斯特大學巴普蒂斯特醫療中心的研究小組在波士頓的一個會議上展示了他們的研究成果。
英國專家們說，這是“激動人心的進展”，但目前還不確定是否有可能培養出功能健全的肝臟。
對可供移植肝臟的需求遠超過所能供應的數量。近年來，研究工作的重點一直放在尋找用細胞技術維持或終有一天替代人體衰退器官的方法上。這些器官的基本構件是干細胞，一種在特定條件下分裂，形成各種人體組織的重要細胞。然而，用干細胞構建一個三維器官是一件困難的工作。
韋克福雷斯特大學的研究人員以及世界上其他研究小組所使用的方法是，以現有肝臟結構為平臺，生成新的肝臟組織。
按照這種方法，研究人員利用一種洗滌劑剝離肝臟細胞，只留下支撐肝臟細胞的膠原框架和毛細血管網絡。然后，新的干細胞———發育不完全的肝臟細胞以及用于生成新血管內壁的內皮細胞———被逐漸填入。
將這些放入用各種營養物和氧氣培養細胞的生物反應器中，一周后，科學家們觀察到肝臟結構中出現普遍的細胞發育現象，并且這個小型器官甚至出現一些正常工作的跡象。
領導這項研究的謝伊·瑟凱爾教授說：“我們為這項研究展現的可能性感到激動，但必須強調的是，我們還處于初級階段，還必須克服許多技術障礙才能讓病人受益于這項研究。”
他說：“我們不僅需要弄清如何一次性培養大量肝細胞，以便為病人制造足夠大的肝臟，我們還必須確定使用這些器官是否安全。”
英國研究人員認為這項研究成果是可喜的。英國帝國理工學院教授馬克·瑟斯說，這些研究成果“鼓舞人心”。
他說：“報告顯示，這些研究人員攻克了制造人造肝臟的主要障礙之一，即在‘自然生成的’肝臟結構中培養出正常工作的人類肝臟細胞。”
他說：“很明顯，這些細胞發育良好，但下一步是要證明它們能夠像人類正常肝臟組織那樣工作。”

原文如下：30 October 2010Last updated at18:30 GMTMiniature livers 'grown in lab' Scientists have managed to produce a small-scale version of a human liver in the laboratory using stem cells.
The success increases hope that new transplant livers could be manufactured, although experts say that this is still many years away.
The team from Wake Forest University Baptist Medical Center presented its findings at a conference in Boston.
UK experts said it was an "exciting development" but it was not yet certain a fully-functioning liver was possible.
Continue reading the main storyRelated storiesLab-grown liver transplant hope

The demand for transplant livers far exceeds the number of available organs, and in recent years, research has focused on ways to use cell technology to support failing organs in the body, or even one day replace them.

Their building block is the stem cell, a "master cell" which can, in certain conditions, divide to produce different types of body tissue.
However, constructing a three-dimensional organ from stem cells is a difficult task.
'Technical hurdles' The method used by the Wake Forest researchers, and other teams around the world, is to form new liver tissue on a scaffold made from the structure of an existing liver.
In this case, a detergent was used to strip away the cells from the liver, leaving only the collagen framework which supported them, and a network of tiny blood vessels.
Continue reading the main story“Start Quote

Whilst 'off the shelf' new livers are clearly still a long way off, this work gives a glimmer of hope that this is no longer just the stuff of science fiction”

Dr Mark Wright,Southampton University

The new stem cells - in this case, immature liver cells and endothelial cells, to produce a new lining for the blood vessels - were gradually introduced.

After a week in a "bioreactor", which nurtured the cells with a mixture of nutrients and oxygen, the scientists saw widespread cell growth within the structure, and even signs of some normal functions in the tiny organ.
Professor Shay Soker, who led the research, said: "We are excited about the possibilities this research represents, but must stress that we're at an early stage, and many technical hurdles must be overcome before it could benefit patients.
"Not only must we learn how to grow billions of liver cells at one time in order to engineer livers large enough for patients, we must determine whether these organs are safe to use."
UK researchers welcomed the findings, which are being presented to the American Association for the Study of Liver Diseases. Professor Mark Thursz, from Imperial College London, said the results were "encouraging".
"The report suggests that the authors have overcome one of the major hurdles in creating an artificial liver - to generate functioning human liver cells in a 'natural' liver structure.
"It is clear that the cells are growing well, but the next step is to show that they are functioning like normal human liver tissue."
Dr Mark Wright, from Southampton University added: "In an era of increasing liver disease and death with a chronic shortage of liver transplants this represents an exciting development in an important field of work.
"The researchers appear to have made the step of combining stem cell technology with bioengineering as a first step to producing artificial livers.
"Whilst 'off the shelf' new livers are clearly still a long way off, this work gives a glimmer of hope that this is no longer just the stuff of science fiction."

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