科学，客观，诚实谈论肝细胞疗法的未来....

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肝脏细胞疗法进展及其前景——Sanjeev Gupta访谈
来源：国际肝病作者：发布时间：2008-11-25阅读：68
导读：事实上，肝病细胞疗法已经进行了差不多20年的研究，全球约有100位患者接受过肝脏细胞疗法。初期积累的经验表明在这方面还有更多的研究工作要做。

Hepatology Digest ：You have done great work in the area of liver cell therapy but it appears most cell therapy studies are still in the lab. In your opinion, when can the cell therapy be used in clinical treatment of liver diseases?

国际肝病：您在肝脏细胞疗法方面做了大量研究工作，但目前大多数细胞疗法还处在实验室研究阶段。您认为细胞疗法什么时候能够用于肝病的临床治疗？

Sanjeev Gupta：If fact, cell therapy for liver disease has been attempted for nearly two decades and some 100 patients world-wide have already been treated with liver cell therapy.  The initial experience that has already been accumulated indicates that more work needs to be done.  What we have certainly learned is that cell therapy is safe to be done in patients and that there are certain types of precautions that will need to be taken to make sure there are no complications.  And what we have learned is that for the maximum efficacy of cell therapy, certain types of manipulations need to be done, such that the number of transplanted cells can grow in the liver to correct various diseases.  Having said that, what this implies is that future efforts for cell therapy are likely to be much more effective than what has been done so far.

Sanjeev Gupta教授：事实上，肝病细胞疗法已经进行了差不多20年的研究，全球约有100位患者接受过肝脏细胞疗法。初期积累的经验表明在这方面还有更多的研究工作要做。我们已经知道对患者进行细胞疗法是安全的，要采取一些预防措施确保无并发症发生。此外我还知道要让细胞疗法发挥最大疗效，需要采取一定的处理措施，使移植细胞能够在肝脏增值，从而达到治疗各种疾病的目的。这意味着我们要更加努力使将来的细胞疗法比目前治疗更加有效。

Hepatology Digest ：You mentioned that there are still things to be learned: What would those things be?

国际肝病：您提到还有更多的事情需要研究，能谈一下是指那些方面吗？

Sanjeev Gupta：Several areas are important.  One of the areas of paramount significance is how cells can engraft efficiently in the liver.  How cells can then proliferate in the liver to acquire a certain mass that would be sufficient for therapeutic benefits.  That then involves a number of mechanisms that concern the transplanted cells themselves as to what their intrinsic properties are and interactions between transplanted cells and cells in the recipient liver where those interactions can direct whether cells can engraft appropriately without clearance of a large number of transplanted cells.  And then manipulations in the recipient liver, either because of diseases that are happening, or because there is no disease and the liver is normal but it can hurt native cells or change them in some such way that transplanted cells will have the benefit to proliferate.  Those are the conditions where they can be a much better therapeutic effect. So, that is one area.

A second area as a whole is understanding what can be done to prevent rejection of mismatched cells because healthy cells must generally come from another person. Those cells would ordinarily be rejected. So, there are lots of advances happening in the area of rejection and that should be helpful, again, in improving results.

And a third area, briefly, is finding the right types of cells, because donor organs are in short supply.  That is the area where stem-cell biology comes into play.

Sanjeev Gupta教授：有几个方面很重要，其中极其重要的一个方面是如何将移植细胞高效植入肝脏以及如何让移植细胞在肝脏增值到足够的数量以达到治疗效果。这包括移植细胞自身的一些机制，如移植细胞自身的一些内在特征，以及移植细胞和受者肝脏细胞间的相互作用，这些作用能够决定移植细胞能否以适当的方式植入肝脏而不会导致大量移植细胞的清除。因此，对于受者肝的处理，要么因为现患疾病，要么尽管无病并且正常肝脏，但是能够损伤自身自然细胞或以这样的一些方式使它们发生改变，那么将会对移植细胞增值有利。这种情况下将会有较好的治疗效果。

第二个方面是要理解我们应该采取什么样的措施来阻止细胞因不匹配而发生的排斥，这是因为健康细胞常常来自于另一个人，通常情况下这些细胞会被排斥掉。目前在排斥领域已经有很多进展，进而可以帮助改善治疗效果。

第三个方面就是要找到合适的细胞类型，因为供体器官不足，而这是肝细胞生物学研究的领域。

Hepatology Digest：Is the end-goal of that ultimately – and this might should like science fiction – to grow a whole new liver from those cells?

国际肝病：是否就像科幻小说那样最终的目标是让移植细胞长成一个完整的新肝脏？

Sanjeev Gupta ：That is the idea.  In certain circumstances the native liver of the person needs to be substantially replaced with healthy cells.  One such circumstance would involve a genetic defect where the majority of cells have to be replaced for that deficient function to be corrected.  Another circumstance would be in people with chronic hepatitis where most cells are damaged, one would need to replace virtually all of those cells to prevent further complications.

On the other hand, there are circumstances where the organ is failing, such as an acute liver failure due to drug toxicity or due to a virus infection or due to other conditions where if it were possible to provide some limited support for a short while, it may be that the injured liver could recover and that would constitute another effort of cell therapy.

Sanjeev Gupta 教授：那正是我们想要达到的目的。在一些情况下患者原来的肝脏须要被大量健康的细胞所取代。其中一种情况与遗传缺陷有关，为了恢复其缺失的功能，大量的细胞需要被取代。另一种情况是大量肝细胞发生损伤的慢性肝病患者，常常需要取代所有损伤细胞来阻止并发症的进一步发生。

另一方面，在器官发生衰竭的情况下，如由于药物毒性或病毒感染或其它一些情况导致的急性肝衰竭，如果能尽快提供一些的有限支持措施，可能会使损伤的肝脏功能恢复，那是细胞治疗要努力的一个方面。

Hepatology Digest：And how close are we to that?

国际肝病：您能谈一下我们离这一目标还有多远呢？

Sanjeev Gupta：Each passing year we learn more and each passing year we become closer to doing things ever better.  The confluence of different kinds of advances and that includes basic science, but it also involves economics, and in some ways it involves politics, and in some ways it involves societies and communities as a whole -- for example where stem-cell research is concerned.  All of that has to come together in the right time in the right way for us now to make substantial progress.  

Sanjeev Gupta教授：过去的每一年我们都学到了更多的经验，而且我们也做得越来越好。目前众多的进展包括基础科学方面，此外也包括经济学，在一定程度上也包括政治和相关科学团体，如对干细胞研究的关注。所有这些进展一起在正确的时间以正确的方式使我们能够取得更大的进步。

Hepatology Digest ：In the April of 2008 Journal of Cell Science article, of which an author, you addressed Fetal Human Liver Epithelial Cells. The question is: If fetal human liver epithelial cells displayed stem cell properties can they be used in the clinical liver cell therapy?

国际肝病：2008年4月，作为作者之一您在Journal of Cell Science杂志上发表了一篇关于人胎儿肝脏上皮细胞的文章。我的问题是：如果人胎儿肝脏上皮细胞表现出干细胞特征，那么它们能否用于临床肝脏细胞疗法？

Sanjeev Gupta：Absolutely.  We are very excited about that particular paper and the data it contains because this is the first time that the properties of a fetal liver stem cell have been characterized in that manner. So what that paper especially demonstrates is that there is a unique stage that fetal liver cells exhibit, which identifies them at an early stem progenitor condition.  And that is very important not only for understanding how pluripotential stem cells could be converted to reach that stage but also to determine how these cells could mature and replace functions – before or after transplantation – for various purposes.  The ability to isolate these cells in effective manners and sufficient numbers is extraordinarily important for early applications of cell therapy, because we are still in the dark about how to convert embryonic stem cells or induced pluripotential stem cells to these kinds of stages.  These cells are natural stem cells.  There has not been any requirement to genetically modify them. And the FDA and other regulatory bodies, for example, are quite happy with the use of these cells for clinical applications.  Therefore developing early clinical studies is definitely very, very feasible with these cells.

Sanjeev Gupta教授：这是毫无疑问的。我们对那篇文章及其研究结果感到十分兴奋，因为这是第一次发现胎儿肝脏干细胞具有那种特征。那篇文章特别指出存在一个独特的阶段，胎儿肝脏细胞表现出早期前体干细胞的特征。这不仅对于理解多能干细胞是如何转变到这一阶段很重要，而且对于确定移植前后，这些细胞是如何成熟并获得相应功能也很重要。如何以高效的方式分离这些细胞并获得足够数量，对于早期细胞疗法的应用十分重要，因为我们还不清楚如何转变胚胎干细胞或诱导多能干细胞达到这样的阶段。这些细胞是自然干细胞，不需要对它们进行遗传修饰。并且FDA和其它一些管理机构很高兴看到在临床应用使用这类细胞。因此对这类细胞开展早期临床研究是十分可行的。

Hepatology Digest ：So, that does lead to the next question: What is the criteria for cells that can be used for clinical liver cell therapy?

国际肝病：因此我的下一个问题是：对于能够用于临床肝脏细胞疗法的细胞有什么样的标准呢？

Sanjeev Gupta ：The three major criteria will be: First, any given cell preparation must be well characterized, should be free of contaminations – such as bacteria or viruses -- and should have performance specifics that would indicate that cells will do their job.  The second important criterion would be that these cells should be studied appropriately in defined systems to know that they are going to work in people.  The third appropriate consideration would be that these cells should have the capacity to correct deficient functions in people without turning themselves into tumors or cancer forming types of cells and there should be a lasting improvement once they are put into people.

Sanjeev Gupta 教授：主要有三个标准，首先是准备的细胞必须特征明确，无细菌或病毒污染，此外还要证实这些细胞能够发挥其功能。其次是这些细胞应该在合理确定的系统中进行研究以明确它们将要在人体内发挥的功能。最后要考虑的是这些细胞具有纠正患者自身细胞功能缺陷的能力，而它们自身不会转变成肿瘤或形成癌症的细胞类型，并且输入到患者体内后应该具有持久的治疗作用。

Hepatology Digest：There is now no effective treatment for Wilson’s disease related liver cirrhosis besides liver transplantation. We noticed your paper Development Of Cell Therapy Strategies To Overcome Copper Toxicity In The LEC Rat Model Of Wilson Disease published in Regenerative Medicine in which you addressed this subject.  So tell us Doctor, what is your perspective on the work that should be done before cell therapy can be used for treatment of Wilson’s disease?

国际肝病：除了肝移植外，目前还没有有效治疗Wilson病相关肝硬化的方法。您在Regenerative Medicine杂志上发表了一篇名为《开发细胞治疗策略来克服鼠Wilson病模型铜毒性》的文章，在这篇文章中您提到了问题。那么，您能告诉我们在细胞疗法用于治疗Wilson病之前我们还须要做些什么？

Sanjeev Gupta ：That is a good question.  Wilson’s disease is relatively uncommon, and there is a severe accumulation of copper in this condition which then badly damages liver cells.  And because those cells are perpetually damaged, it is necessary to have healthy cells that have the capacity to remove copper from the body come into the picture.  And it is necessary, then, for those cells to gradually take over the liver such that the diseased cells go away and the liver gets renewed.

Now while there is intrinsic pressure or circumstances exist intrinsically for transplanted cells to grow and to proliferate in the liver of animals with Wilson’s disease – and by inference that should be what will happen in people with Wilson’s disease.  It has been necessary to accelerate that process for the liver to get taken over by transplanted healthy cells. And that is where we have uncovered differences in what may work well in a normal, healthy liver in terms of the damaging kinds of treatments or preparations that can be done before transplanting cells.  Whereas in Wilson’s disease livers those manipulations do not always work in the same way, and why there is a difference is very important to understand.  There are genetic reasons for those differences and there are differences in the way cells respond to certain injuries and the way how they are adaptive to secondary changes that occur in cells to avoid those kinds of damages.  Through those intrinsic alterations, some of these conditioning regimens that we have been using don’t have the same efficacy in this condition.  And so that raises the question: what else could we do?  What other kinds of mechanisms could we employ in this and other conditions?  And that is where more work needs to be done.  It is also important to keep in mind while we understand these kinds of processes and mechanisms, that Wilson’s disease is only one such example.

There are other kinds of chronic conditions, say, chronic viral hepatitis, where again there would be somewhat similar – not exactly identical – processes happening. And we will likely need to do more work under those conditions to define what manipulations will be appropriate.  How would they differ from a normal liver or a liver with other kinds of damage?  And what will be made under those disease-specific conditions?

Sanjeev Gupta教授 ：这个问题问得很好。Wilson病相对来说不是很常见，患有该病的患者，在其肝脏有异常的铜累积进而导致肝细胞严重损伤。由于这些肝细胞的损伤是永久性的，因此须要有健康功能的移植细胞来清除体内异常累积的铜。并希望这些健康细胞逐渐取代肝脏损伤的细胞，从而使肝脏再生。

在Wilson病的动物肝脏对于移植细胞的生长和增值存在内在的压力，推断这种情况也存在于人Wilson病患者。我们需要加速移植健康细胞取代肝脏损伤细胞这一过程。我们发现对于正常健康肝脏细胞，在治疗损伤类型或移植细胞前处理措施方面存在差异。而在Wilson病肝脏，这些处理措施常常并不以相同的方式发挥作用，这对于理解为什么有这种差异十分重要。这有遗传方面的原因，也有移植细胞对特定损伤应答方式上的差异，以及它们以何种方式来适应细胞为防止这损伤而出现的继发改变。由于这些内在改变，我们使用的一些疗法在这种情况下并未表现出相同的疗效。因此问题出现了：我们还能做些什么呢？在这种情况下，我们还能利用什么样的机制来治疗呢？在这些方面我们还有更多的工作需要做。我们应该知道Wilson病只是其中的一个例子，这对我们理解这些过程和机制很重要。

还有其它一些慢性疾病状态，如慢性病毒性肝炎，其过程在某种程度上与此有些类似，虽然并非完全一样。我们须要更多的研究以确定在这种情况下哪些处理是合适的。此外在正常肝脏和其它类型损伤的肝脏有什么不同？对疾病特异性的情况需要采取哪些措施？这都是我们须要考虑的问题。

Hepatology Digest ：In that same paper, you mentioned that suitable mechanisms for inducing transplanted cell proliferation will be critical for therapeutic success. And your paper Hepatocyte Transplantation And Drug-Induced Perturbations In Liver Cell Compartments in Hepatology you mentioned that targeted injury in hepatic endothelial and parenchymal cells with suitable drugs will also help advance liver cell therapy.  What progress has been made in the area of inducing transplanted cell proliferation?

国际肝病：同样是在那篇文章中，您提到合适的诱导移植细胞增值的方法对于成功的治疗十分关键。另外您在Hepatology杂志上发表的文章《肝细胞移植以及药物诱导的肝细胞扰动》中提到使用合适的药物靶向诱导肝脏内皮细胞和实质细胞损伤也能帮助改进肝脏细胞疗法。那么，您能谈一下在诱导移植细胞增值方面已经取得了那些进展呢？

Sanjeev Gupta：That, again, is an excellent question.  There are two types of compartments we are talking about.  The hepatocyte compartment refers to cells within the liver parenchymal that are responsible for hepatic functions such as secretion and synthesis of certain proteins -- albumin is one prime example of that – or detoxifying drugs, providing glucose to the body, or restoring glycogen, and so on.  It is these cells that are responsible for certain diseases.

There are other cell types – particularly the endothelial cell compartment – which constitutes the next largest type of cell within the liver. It is the endothelial cells that are responsible for a variety of other types of specialized functions，including, for example the production and secretion of the colligation factor called “factor VIII” which is lacking in patient with hemophilia-A.  What we have learned is that while replacement of hepatocytes is beneficial for certain kinds of diseases, it possible to replace healthy endothelial cells and that can be effective for curing hemophilia-A . That, then leads to the question as to what can be done to impair survival of either of those types of cells in the liver such that transplanted cells can then have a survival advantage and they can proliferate better.  And that is where some of these drug-based regimens that we have been developing will be useful because if we can understand how to target them to one cell compartment or the other and to develop appropriate cocktails of combinations of these drugs, then we will be able to achieve one of the central goals of cell-therapy, which is to have enough masses of transplanted cells that it will have a therapy benefit.

Sanjeev Gupta教授：这也是一个很好的问题。肝细胞是肝实质的主要组成细胞，负责肝脏各项重要功能，如分泌和合成特定的蛋白（白蛋白只是其中之一），或解毒药物，给机体提供葡萄糖，或储存糖原等功能。这些细胞与特定的疾病有关。

此外也有其它细胞类型，特别是内皮细胞，是组成肝脏的第二大类细胞。内皮细胞负责其它一些特殊的功能，如产生和分泌连接因子“VIII因子”， A型血友病患者缺少的正是这种因子。我们已经知道取代损伤肝细胞对一些特定疾病有利，而用健康的内皮细胞取代异常细胞来有效治疗A型血友病是有效的。这样就出现了一个问题，即我们应该采取怎样的措施来破坏这些异常细胞的生长，从而使移植细胞能够具有生长优势进而可以更好的增值。如果我们理解了如何靶向作用于某一种细胞类型，并开发出适当药物联合的鸡尾酒疗法，这样就能有足够数量的移植细胞从而产生较好的治疗效果，那么我们就能达到细胞疗法的主要目标。

Hepatology Digest ：If cell therapy is used for clinical therapy of liver diseases, the problem of getting enough cells for transplantation and ethics issues need to be solved. Doctor, please give us your opinion about these issues.

国际肝病：如果细胞疗法用于肝病临床治疗，须要解决如何获取足够的移植细胞和伦理方面的问题。您能谈一下您在这些问题上的观点吗？

Sanjeev Gupta：There are three major sources of cells that would be appropriate for cell therapy.  The first such sources are from adult donor organs, where the liver itself, for example, constitutes an appropriate source.  But donor livers are in short supply. There are alternatives to that.  For example one can make adult stem cells from blood, from bone marrow, from placenta, from cord-blood; but those cells are not always as effective for cell therapy -- even though there are not many ethical or social issues associated with them.

That then leads us to consider whether fetal cells would be appropriate, and whether embryonic stem cells – or cells made from individuals -- so called inducible pluripotent stem cells – would be useful.  There are not ethical issues surrounding inducible pluripotent stem cells, because again they are from adults and they are from Somatic cells, but there is a problem – at the moment – because these cells have the be genetically manipulated so they are not going to be ready immediately for clinical application.

As far as the ethical issues surrounding fetal cells are concerned, these are equivalent to the use of cadaveric organs.  Now there is a long-standing history of our communities, societies worldwide of doing transplant of organs from cadavers.  Fetal tissues are, again, in the same way cadaveric tissues which would be procured from materials that would otherwise be discarded.  The ethics of that source of tissue has been well-considered and has been resolved in most societies and communities and there is generally no restriction about transplantation of those cells under appropriately regulated sites.

The biggest source of contention has been the use of embryonic stem cells, both for research and further applications, especially since the federal government restrictions from earlier in the decade against destruction of embryos to generate new cell lines with federal support.  That has not prevented efforts to generate new cell lines, and in fact hundreds of new cell lines have been made through funds that are non-federal.  The ethics of working with those cells has been debated – and is undergoing additional debate – but those are issues that can be resolved though the involvement of communities and learned and wise people.  There is all the reason to hope that once all those issues are resolved – and once ways have been developed to manipulate embryonic stem cells or induced pluripotential cells to generate tissues and cells of interest – we will reach a point where we will have a healthy debate and an outcome that would be beneficial to mankind rather than lead us to become retrogressive.              

Sanjeev Gupta教授：主要有三种来源的细胞比较适合用于细胞疗法。第一个来源是成人供体器官，肝脏本身就构成了一个合适的来源，但是供体肝脏不足，对此有一些可供替代的选择。比如我们可以从血液，骨髓，胎盘，脐带血获得成人干细胞；但是这些细胞用于细胞疗法并不很有效，尽管它们不存在相关的伦理和社会问题。

这使我们考虑把胎儿细胞，胚胎干细胞或来自自体的诱导多能干细胞用于细胞疗法是否是合适并有效的。诱导的多能干细胞也没有伦理方面的问题，因为这些细胞来自于成人体细胞，但是目前也存在一个问题，因为这些细胞需要经过预先的遗传处理，因此不能立即用于临床治疗。

而胎儿细胞有伦理方面的问题，尸体器官使用也存在类似的问题。而目前世界范围内施行尸体器官移植已经有较长的历史。而胎儿组织也可以称之为尸体组织，因为这些胎儿组织是从那些将要被丢弃的组织中获取的。对于胎儿组织的伦理问题的争论已经受到广泛关注，并且胎儿组织的使用已得到大多数科学团体的认可。通常在合适的情况下，对这种细胞的移植并没有限制。

最大的争议在于胚胎干细胞的使用，不论是科学研究还是进一步的应用，特别是联邦政府早在十年前就限制资助通过破坏胚胎来形成新的细胞系的研究。但这并没有阻止通过这种方法形成新的细胞系的努力，事实上，通过非联邦的基金支持，已经形成了数百种新的细胞系。对于这类细胞研究的伦理问题还在争论之中，但是这些问题最终一定会得到解决。我们有理由期盼所有这些问题得到解决，而且，一旦能够让胚胎干细胞或诱导多能干细胞形成我们感兴趣的组织和细胞，这将对人类有益，而非使我们倒退。



翻译：北京大学第一医院感染疾病科吴学杰
审校：北京大学第一医院感染疾病科吴学杰

坚韧地活着

细细地看完了，感谢411老师为我们提供这些真实的、科学的，前沿的医学动态信息，让我们更加有信心等待。