干细胞技术已能制造出小型人类肝脏
【英国广播公司网站10月30日报道】科学家们设法利用干细胞在实验室制造出小型人类肝脏。
这一成功增加了制造出可用于移植的新肝脏的希望，尽管专家们说这还需要很多年时间。
来自美国韦克福雷斯特大学巴普蒂斯特医疗中心的研究小组在波士顿的一个会议上展示了他们的研究成果。
英国专家们说，这是“激动人心的进展”，但目前还不确定是否有可能培养出功能健全的肝脏。
对可供移植肝脏的需求远超过所能供应的数量。近年来，研究工作的重点一直放在寻找用细胞技术维持或终有一天替代人体衰退器官的方法上。这些器官的基本构件是干细胞，一种在特定条件下分裂，形成各种人体组织的重要细胞。然而，用干细胞构建一个三维器官是一件困难的工作。
韦克福雷斯特大学的研究人员以及世界上其他研究小组所使用的方法是，以现有肝脏结构为平台，生成新的肝脏组织。
按照这种方法，研究人员利用一种洗涤剂剥离肝脏细胞，只留下支撑肝脏细胞的胶原框架和毛细血管网络。然后，新的干细胞———发育不完全的肝脏细胞以及用于生成新血管内壁的内皮细胞———被逐渐填入。
将这些放入用各种营养物和氧气培养细胞的生物反应器中，一周后，科学家们观察到肝脏结构中出现普遍的细胞发育现象，并且这个小型器官甚至出现一些正常工作的迹象。
领导这项研究的谢伊·瑟凯尔教授说：“我们为这项研究展现的可能性感到激动，但必须强调的是，我们还处于初级阶段，还必须克服许多技术障碍才能让病人受益于这项研究。”
他说：“我们不仅需要弄清如何一次性培养大量肝细胞，以便为病人制造足够大的肝脏，我们还必须确定使用这些器官是否安全。”
英国研究人员认为这项研究成果是可喜的。英国帝国理工学院教授马克·瑟斯说，这些研究成果“鼓舞人心”。
他说：“报告显示，这些研究人员攻克了制造人造肝脏的主要障碍之一，即在‘自然生成的’肝脏结构中培养出正常工作的人类肝脏细胞。”
他说：“很明显，这些细胞发育良好，但下一步是要证明它们能够像人类正常肝脏组织那样工作。”
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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