Stephen Minger: "“Therapeutic and research potential of human pluripotent stem cells�? (EN, IT)
I am grateful to Marco for the invitation. I have found this meeting to be very, very interesting, as I have heard some of the best intellectual discourses all together in one time. So I am happy to be here.
Particularly in response to some of the presentations held yesterday, I have really changed the focus of what I should have been talking about. Thus I will briefly touch on the therapeutic and research potential of stem cells. But I also want to tell you a little bit of a story till the end, which I think is a tremendous successful story for science; in particular about the legislation that has been changed over the last 3 years in the UK.
As it is, I think this story is actually emblematic of how much power scientists really have. But it requires a huge amount of deferring and scientists have to learn how to fight if they want to change religion and dogma and government perspectives. So I will take you through this rules scenario.
First of all, let me say that in my lab, like many others, we have been focused on the use of stem cells for many years now. I myself have been a stem cell biologist for 20 years. This lays out what we do. So a lot of our work is devoted towards developing cell therapy, that is pluripotent cells. But we use other stem cell populations as well. And we are very agnostic with regard to stem cells. Therefore we focus on clinical application. And we go for the best, most available population we can.
We are interested in trying stimulation in tissues, working on the adult nervous system, where they can be mobilized. We try to understand how this happens and if we can exploit it, having in mind new therapies for the brain. In fact we think that if we can develop technologies which allow us to differentiate into very specific cell populations, we can also use those cells in fundamental drug discovery.
The real problem with Big Pharma is that their drugs screens are based on the use of tumor cells or primary cells and that leads to a lot of drugs that end up in phase 2/3 and then fail; and that is a part of the reason why it costs so much to develop new compounds. On the other hand, by using pluripotent cells we can differentiate them into a wide variety of different types of cells and we can use those cells as new screens for drugs. So we are eventually using human cells as defined cellular populations to develop new therapies. And, last but not least, we can also use these to – and this is the real point that I want to talk about – develop what we call disease specific cell lines, or rather human embryonic stem cells that include disease-causing genes. And that I will save for the end, because it leads into a nice story.
First of all this goes just to show you that there are a plethora of different stem cell populations. Really we think that in the course of their development we have the most potent stem cells. Then, as the development proceeds, stem cells become more and more restricted in terms of their ability to give us different tissue types. Anyway, as professor Cossu pointed out, the dogma has now changed. And we, too, think that nowadays it might be possible for development processes to actually go backwards, because at present with induced pluripotent cells we can take other mature differentiated cells, and with exhausting genetic engineering at a current time we seem to be able to take them backwards in time and take them to embryonic stem cells.
Nevertheless, the field is rapidly developing. New stem cell populations are being found all the time. We, together with our colleagues, showed that in the adult male testes, for example, there appears to be a stem cell population that looks like embryonic stem cells as well. We hardly know what these cells do, nevertheless they seem to have all the attributes of a few many other stem cells.
We have stem cells from fat, stem cells from baby teeth, stem cells from toe nails… There are stem cells everywhere. We work on all of them. We make no distinction between all these types of populations. As for me, I am a scientist, I am not a moralist, and I work on what I need for clinical applications. Now I think these cells are the cells that have the most fierce utility for us.
Embryonic stem cells are derived from the very early human embryo. They are the very first cells which arise in development. We can take these cells out of the developing blastocyst at a time before which they express any indication of any specific tissue. You can put these cells into culture and under conditions that we still do not really understand - these working conditions were developed back in the 1980s - these cells will expand to very, very large numbers, without aging.
These cells run like any other cell population in the human body, because they never get old. They just keep growing and growing and growing. We have had cells in culture continuously for years and they just keep expanding and yet they retain the ability to differentiate into all these different cell types. Today we do not know of any other cell population that can do that, although the induced pluripotent stem cells may be very analogous to this behavior. But without cells derived from early human embryos, we do not really know what induced pluripotent stem cells are; and whether or not they have the same capabilities as the human embryonic stem cells.
Now, I am fortunate to work in a very enlightened environment. In the UK we have some of the strictest regulations around the derivation of the human embryonic stem cells. And that really grows out of a very long history of regulation of reproductive medicine.
So Louise Brown, the first test-tube baby, the first IVF (in vitro fertilization) embryo was born in the United Kingdom in 1978. IVF was a technology that was developed by the UK medics Bob Edwards and Patrick Steptoe. After Louise Brown’s birth there was a huge amount of controversy about IVF. Was this playing God? Was this leading to designers of babies; was it eugenetic engineering of embryos; braving the world; 1984… and all of that. Then there was a lot of debate and discussion, which led to which was called the Warnock Commission meeting in 1985. And the major recommendation from that consultation was that the UK should establish a regulatory body to regulate reproductive medicine.
Parliament took that suggestion and in 1990 we enacted the Human Fertilization and Embryology Act which led to the Human Fertilization and Embryology Authority. Every clinic in the UK, were they public or private, are now regulated by this authority. And they had to obtain a license for every procedure which they might perform within that clinic.
Because IVF is notoriously inefficient and very large numbers of embryos are derived on account of it, but will never be used clinically, it had been recognized since the early 1990s that there would be literally thousands of unused embryos. I will explain why, in a moment or so. Because of that, since 1991 it has been permitted to use human embryos for research in the UK. And today some 20.000 embryos have been used for research since then. But this is not trivial.
In order to gain a license from the HFEA (Human Fertilization and Embryology Authority) before 2001, you had to prove to the authority that the research you wanted to do could only be done with human embryos, not with mouse embryos or cow embryos or anything other than human embryos. The research had to specifically address the following five research sectors: Treatment of Infertility; Causes of Congenital Diseases; Causes of Miscarriage; Development of more Effective Conception; Improvements in Preimplantation Genetic Diagnosis. And the research had to be necessary or desirable. But: what does “necessary or desirable�? mean? Anyhow, this is how the authority would make a decision…
You all do notice that you cannot, for example, use human embryos for cosmetic testing. You cannot use them to test food additives. Neither of those uses are necessary and they are not desirable. That was the status quo up until 2000 or so. And then Jamie Thompson and others developed some of the first human embryonic stem cell lines. After that they were trying very hardly to get access to those cell lines; which was difficult because these groups were just ever the first in the world and researches were struggling to learn how to grow those cells. Secondly, there were hundreds of research groups who wanted those cells and it was clear that it was going to be years before cell lines were made available.
The UK government pushed through what is called the extension of the Act. In 2001 both Houses of Parliament added to the five original research areas three new research areas where one could use human embryos. And that was meant to lead to a better understanding of human development, to a better understanding of disease processes and to develop new therapies for human diseases. These latter two areas allowed me and my colleagues in 2002 to apply for a license for a line of human embryonic stem cells. Together with Austin Smith’s group, we got one of the two licenses in force in the UK.
What you hear from me is the real picture of the ethical environment in which I work. We are allowed to approach couples, either at the time that they are undergoing a consultation about IVF or are going to make a decision about what to do with embryos, because in the UK you can only freeze embryos for 5 years. At the end of that period, the couple have to make a decision about what to do with those embryos. Usually the decision boils down to this: should I have them destroyed or donate them for research? Most couples who have kept them, have completed their fertility treatment. So they are not going to use them. Rarely they will donate them to other couples. So, the real distinction is again: do I have to destroy them or donate them for research? That is the reality of embryo donation.
In the UK couples can donate them under consent. They are not given inducement for donation. They do not get half price IVF. As a matter of fact, they sign away all rights to any cell line which may be developed. They cannot dictate how they are to be used; nor have any control whatsoever over them. We let them know that the cells may be used commercially. And that someone may make a lot of money. And that they go to a Big Pharma company, where they may develop a drug out of them. Not a single penny will ever come back to the couple. Therefore they have no reason to donate embryos, except for the fact that they rather see them used for research, than destroyed.
One of the other things that came out of the new legislation in 2002 was a stipulation that anyone who is granted a license to derive human embryonic stem cells is required to place the corresponding cell lines into the UK Stem Cell Bank, where they are available to any researcher in the world, as long as the research they want to carry on is ethical and sound. Our research lines have been exported to Italy. But unfortunately the Italian colleagues cannot use our lines, because they do not get funding to support that research.
Somatic cell nuclear transfer which is commonly referred to as “therapeutic cloning�? using human eggs is legal in the UK, but we completely banned reproductive cloning in 2001. Let me point out that all of these points are not guidelines. They are statutory.
If I violate any of these rules, for example: if I were to offer someone money for their embryos, or if I would implant embryos that I made by cloning into someone’s uterus, I would go to prison for 10 years. That is true for anyone who is licensed by HFEA. And there are severe penalties if you step out of license. What I think of is really the model system about how to do ethically contentious research where you have very tied, very rigid regulation, versus one system that is scientifically permissive. I will show how this has changed over the years.
This is the scene in 2002. This is how you make human embryonic stem cells. We have done this, like a certain number groups worldwide. This is routine IVF: normally the first day – that is immediately after fertilization - before the nuclei are fused, you keep the embryos in culture. You grow them usually till day 3. And then they are implanted. In the UK, unlike Italy, you cannot implant more than 3 embryos. In most cases only 2. The remaining high-quality embryos are generally frozen. And the number of high-quality embryos depends on the number of eggs you start with.
It is not uncommon for women following supra-population to have 15-20 eggs. So any other high-quality embryos which are not implanted are frozen and, as I said, can only be stored for 5 years currently. In order for us to make stem cell lines, we obtain that they are generally frozen at day 3. We culture them until day 6; and the reason of this day 6 is the formation of that entity called blastocyst.
This population of stem cells here, 20-40 cells, this is what turns into you and me. This is the inner cell mass that will go on to turn into the fetus properly. The larger structure is the placenta. In most cases we remove the inner cell mass, put it into culture and derive individual lines of embryonic stem cells. Each line is unique. It comes from a different embryo, and has its own genetics. One line is genetically different from any other line. All of these cell lines are capable to turn into a wide diversity of cell types. They make lung, heart, liver, pancreas, skin, muscle…
They make every cell type we ever looked for. The idea is to take them into clinical applications. This is a list of the things we work on with our lab collaborators, trying to take cells and trying to learn how to differentiate them into cell populations, reproducibly day in and day out, in that scale, because as the professor pointed out, in order to take these cells to the clinic, we have to generate very, very, very large populations of cells, in order to be able to treat the huge number of patients who will benefit from these therapies.
Now I want to shift to making what we call “disease specific cell lines�?. This is the generation of human embryonic stem cells which encode known disease-causing genes; that is genes which, when mutated, give rise to genetic disease. In 2006, when we proposed the work I am going to tell you about, there were only three ways that one could do that.
Of these three ways, one consists in relying on embryos which have been screened by pre-implantation genetic diagnosis (PGD), which is used for couples who are fertile, but who have a risk of passing on a known genetic disorder to their children. An example of that may be a couple who are both carriers of cystic fibrosis gene. Neither of them is affected. But they have a 1 in 4 chance of having a child which will have cystic fibrosis.
Then they undergo IVF. On day 3, when the embryo is at 8-cell stage, the embryologist will remove a single cell from each of the embryos and diagnose those embryos for the presence or absence of the specific disease-causing gene. Those embryos obviously are not used clinically and in general they are discarded. Therefore, as the Clinical King’s is one of the world leaders in pre-implantation genetic diagnoses, we easily recognize that these embryos are a source which present problems, and they are to be destroyed, although they represent a tremendous cellular resource.
Thus, for example, if you can take a cell line with encodes the cystic fibrosis gene - this is the first cell line that we made this way - and if you can differentiate those cells into human lung cells, it gives you a cell population allowing you to begin to try to understand how it is that these deranged proteins interfere with the normal cell function.
The idea is to try to create a model disease in a dish. And because human embryonic stem cells can turn into every cell type, each individual cell line can be used to differentiate those cells into the cells more
specifically affected in any individual disease. The problem with PGD (prenatal genetic diagnosis) embryos is that you get very few of them, because most of these diseases are somehow rare and secondly you never know if you are going to get embryos. Some couples will donate those affected embryos, some will not. So it is not certain that you are going to get embryos with these disorders.
The second way is scientifically quite complex, but basically what you try to do is taking a normal cell line which is free from disease and then replace the normal gene with the muted gene. The idea is to take a normal cell line and introduce a disease-causing gene into it. The third way is a more defined and more accessible way of doing it, which is very simple: it is cloning.
The use of somatic cell nuclear transfer to create cloned human embryonic stem cells is pretty simple. I may use Marco as my example. Cloning involves eggs. You have a source population of eggs, maybe left over from IVF. And you remove the nucleus from the egg. In doing so you remove the genetic identity. At the start, the woman donated the egg; then you take out the DNA (deoxyribonucleic acid) from the woman; so you have now an empty egg, because it has no genetic identity whatsoever. Then we will take a skin cell from Marco and put it into the egg, give the egg a little bit of electricity - you do not even need sperm for this - and a considerably high proportion of the egg will begin to divide. And then we will give rise to an embryo, just like an embryo which has been created by IVF. From that embryo I can take out the inner cell mass.
And then I have a population of pluripotent DNA cells. Forget this nonsense debarment of putting them back to the patient, because it is totally unrealistic. The strength of that lays now in the fact that the cell line has Marco’s genome in it. Every cell that we create from this cloned embryo will be genetically matched to Marco. If Marco had a genetic form of Alzheimer’s disease, that cell line now has that genetic disease. So cloning is a way of creating cell lines from living human patients that you can induce to become pluripotent stem cells that we want to be used for disease ends and would allow us to specifically select known individuals who have a genome when interested in creating very specific cell lines and very specific individuals.
Well, this is great. A great idea! Yet there is just one small problem. Where do you get eggs and how many eggs do you need to be able to create a cell line? In 2005, many of us were thinking about this. We thought this would be easy. We had a friend who had showed how to do it. This is my friend, professor Hwang from Korea in 2004. In his lab in South Korea professor Hwang was the rock and roll superstar of stem cell biology. This guy was it: a supreme scientist in Korea, 60 million dollars from the Korean government to do his cloning work, also flying first class all over the world. That was it. This guy was good. And the reason why they were good to him and his equipe is that they were the world’s best cloners and still are by a mile.
What people do not realize about Hwang and his group is that Hwang is a veterinarian. All his career had been based on cloning livestock. They had hordes of pigs that had been genetically engineered to provide tissues or organs as a bridge for human transplantation. They had hordes of cows genetically engineered so that they could not be infected and give rise to BSE (bovine spongiform encephalitis). He had cloned dogs. Actually, his is still the only group in the world that have successfully cloned dogs. They cloned wolves. They were trying to clone Korean tigers. He even paid the Russian mafia two million dollars for some mastodon DNA, but unfortunately it did not work.
These guys were running a factory. It is estimated that they did between 2 and 3.000 nuclear transfers a day, every day, seven days a week, 365 days a year. And they had been doing that for years. When Hwang first reported that they had successfully cloned a human embryonic stem cell line from 250 human eggs, we all believed it. Look at the expertise that was there: simply astounding…
When he subsequently, one year and an half afterwards, reported that they had improved the efficiency to 10%, we all were wowing over completely. Probably everyone in this room was, as this was simply astounding. Maybe we are not as good as Hwang, and we might need 50 eggs to create one cell line, when Hwang needs ten. But we now know that it was all not true.
Hwang’s group used over 2.200 human eggs from young women, many of whom in his own research group. They did not make a single embryonic stem cell line, a single cloned line. With all their expertise and with the best eggs you are ever going to get, they went right from the ovary into nuclear transfer. If Hwang could not do it with 2.200 fashionably obtained human eggs, how many do I need? If the efficiency is 1 in 10 and I said I should need 50, that means that I should need 10.000 eggs to make each cell line. How many young women in this room would be willing to come in, undergo this super-ovulation, have a needle inserted through the uterus into the ovary aspiring some eggs for my research work, when I need minimally 10.000 to make each cell line?
This could not be ethically justifiable. Much more so, as I and Armstrong - who was also my colleague in Newcastle - had a better idea. We would do what Hwang did, that is we would bring on the cows. Our argument was something like that: what you need is an egg, it has not to be a human egg, because if the argument is that, when you remove the nucleus from the egg you remove its genetic identity, you also remove its species identity. There is no longer a cow in a cow egg that had its nucleus removed. So we have a cow mytocondria, but there is no cow. The cow has gone.
If you take a human cell and you transfer his/her skin cell into this ex-cow egg and it makes an embryo, it has to be a human embryo. It is not half cow and half human; it’s not a cowboy; it’s not a mutant; it’s a human embryo. The mytocondria are going to be hybrid. There will be a small residual population of about 20% which will be hybrid; which, based on previous work in China making these embryos from rabbit eggs, does not interfere with normal function. This is where we were in 2006.
Hwang’s fall from grace happened very, very rapidly by the end of 2005. In February 2006, the national university completed its investigation, discovered none of the cell lines were real. In fact, they all were fake. And he was disgraced.
We had a press conference in London, where we tried to have a retrospective on what this meant for the field of stem cell research and regenerative medicine. At that press conference many of us were asked: if Hwang could not do it with his huge number of eggs, what are you going to do? Lyle (Armstrong) and I said categorically that no one should be using human eggs. We should only be using an alternative source. And we proposed cow eggs. The headlines of the newspapers went crazy over this. But we were serious about it, as this was not a joke. And so in November 2006, Lyle and I filed the license applications to the HFEA.
This meant that the scientists were going to the regulators, saying: “Regulate us. These are human embryos. They fall under the HFEA act. And we want a license to be able to do this work�?. But we did not start the work. There was a lot of discussion about “are these truly human embryos or not�?? And we argued that they were. We might have been cowboys, as somebody pointed out, but we were not. We decided that we would go through the process of getting a license to pursue this work, rather than starting it. The problem was that the government was not receptive.
Over the previous year the government had been looking at revising the original 1990 act and bringing it up to date with changes in reproductive medicine and changes in stem cell biology; and it was going to be a new act. They released the consultation a month after our license application and they categorically said that they would ban all this research. There would be no cowboys. All hybrid embryos would be banned. This was rather interesting. Why?
Why are you going to ban this? If these are human embryos, they are no different from other embryos. So, the scientific community was not happy about it. Nobody wants its own research to be banned. Additionally, we were not given good reasons to support the banning. It was said: I cannot understand why anyone wants to do it. The problem is that the HFEA is an independent regulator, free from the government influence, and the government is trying to tell them what to do. There was a rally, and in January - 2/3 weeks later - we had a huge press conference in London and we defended ourselves.
Moreover, a group of prominent scientists including five Nobel Prize Laureates in an open letter to the Times said to the Prime Minister: this research can be regulated like any other research and should not be banned. The HFEA at an open meeting said they were not certain what the status of the embryos was, that is, whether they were human or they were not. Rather than making a decision about what to do with our license application, they did the proverbial time-out in Britain and they went to consultation. They said they were not going to make any decision with our license application, but would wait until the consultation, which would take at least 8 months. We could have challenged them legally because the HFEA, by statute, has to make a decision in 3 months. We could have forced them to take up a decision. But we decided that we would go through the process and see where we came out the other side.
At about the same time, the select committee on science and technology in our House of Parliament - which is committee of about 15 MPs (members of parliament) who all have some depth of interest or are scientists or medics advising the Parliament on issues regarding science and technology –decided that they would have their own investigation. Over the spring they had a huge consultation. They invited hundreds of people: scientists, bioethicists, lawyers, religious people, nurses, everybody who had an opinion came in. At the end of this, all unanimously said that these were human embryos.
Do go online and look at the select committee’s report. It is thick. It is one of the few select committee’s reports where all of them agreed that this research should be funded. The HFEA later that Summer came to the same conclusion. They were human embryos, they fell within the HFEA act. Therefore our license application could go off for peer review and in January 2008 we were granted our licenses.
If that would be the end of the story, it would have been a tremendous triumph for science, because we won. We had confronted the government from the opposition and through rational discourse, pragmatic consultation, got them to reverse themselves. But we needed something even better than that, because soon afterwards the government had proposed a new bill, a new human fertilization and embryology bill that had started its way through Parliament.
Then at Easter, on Good Friday - I do not know if it is like that in Italy, or in the rest of Europe, certainly in the history of the UK - everybody disappeared and went on holiday. And the Cardinal could not have done this any better. As a matter of fact, on Good Friday he released his Easter Sunday Sermon, saying this research was monstrous, was grotesque; and that he expected the Prime Minister not to put this bill through. Moreover, if the bill would go through, he demanded that individual MPs had a free vote, because catholic MPs, as well as other people in the cabinet, were saying that if they could not vote out of conscience on this bill, they would walk out of the cabinet.
We got caught completely unaware. There was nobody from the government to defend us. Robin Lovell-Badge and I spent the whole Easter weekend on TV, on the radio, in the newspapers, trying to fight this off. The new Minister of Public Health Dawn Primarolo came back from holiday immediately afterwards and said: “I want three things from you. One is: I want to come and visit your labs. Then I want you to make me understand better this research. Thirdly, I want you and your colleagues to get into parliament and fight this bill�?. Because what was in the bill by then was really pretty interesting.
In addition to the cytoplasmic hybrids, which was the little bit of research we wanted to do, which was taking human DNA and putting it into an egg which had its own DNA removed, the government decided they were going to wrap in primary legislation a number of types of hybrid or high-mixed embryos, including, at least in principle, that you could make a true hybrid, that is taking human sperm or egg and fusing it with non-human sperm or egg. This was really contentious, because when the first 3 went through in votes, all the first 3 were voted in favor by 3 to 1.
There were a lot of people who really opposed the true hybrid embryo. And many people told that the government was actually encouraging people to try to create this, but this was not the case. The government was putting this in the legislation so that you could not do these true hybrid without a license. I don’t really understand why people were freaked out about this. As John Harris pointed out, we had had hum-animals for quite a long time. Hybrids had been there for a while, but nevertheless this proved really controversial and yet the bill was passed by a margin of about 80 votes.
We were told over and over again by very conservative MPs that they voted in favor of this because the scientific community went into the parliament and spent hundreds of hours with MPs, working the Minister’s team getting this legislation through. And so that bill is now law. And hybrid embryos are well within that. Now, I am often asked why this happened. This is the reason why. The scientific community took on the government and did not just disappear.
They did not say: “I’ll go back to my lab and dream of something else�?. They fought back. We stood up and fought. We had a huge amount of support from really prominent scientific societies: the Royal Society, the Academy of Medical Sciences, the Wellcome Trust, the Medical Research Council. The heads of these organizations would come into parliament with us. We had support from over 300 patient organizations and charities who would write letters to the Times, urging the government to push this legislation through. They played their own role, trying to convince the MPs to vote for this. The news coverage in general was extremely good.
We had the major scientific journalists on our side. There were the usual headlines like “crazy scientists�? in the tabloids. But in the Times, the Guardian, the Independent, the Telegraph, the real science writers in Britain were very supportive and they did a great job in educating the public. The consultation process I think was absolutely crucial, because the government initially was afraid that there was a huge public opposition to this, but what they discovered was that 60-70% of the people were in favor of this.
Moreover the HFEA’s own consultation showed that if you initially identified people who were opposed to it, generally on grounds of a religious kind, 60-70% of those people would change their mind when they were better informed. A lot of people would say: “What is the problem? We do not see that there is a problem as long as it is regulated. Regulate the hell out of it. Make the scientists accountable, but do not block fundamental research�?. I think it was the Minister Dawn Primarolo who was really crucial in this respect, because she was determined to get this bill through parliament. But she would not have done it without the support offered by the scientists.
“Potenziale terapeutico e di ricerca delle cellule staminali umane pluripot