Stem Cells through the lens of the Korean cloning scandal
Elizabeth Finkel 7th March 2006
Analysing the Korean cloning affair provides a great lens through which to view the general issues of stem cell research.
The affair highlighted the extraordinary challenges and difficulties of harnessing the technique of therapeutic cloning. It showed how great the expectations are of the technology,both to cure intractable medical conditions and as a driver of a “regenerative medicine” industry.
It brought the ethical issues into sharp relief and, in the crucible of scandal, helped rapidly forge ethical guidelines for researchers around the world.
It dredged up the worst nightmares dreamed up by the anti-science lobby and highlighted how legislation needs to be carefully drawn.
SLIDE 2
The promise of embryonic stem cellsboth to cure intractable medical conditions, and as a driver of a “regenerative medicine” industry
Ethical pitfalls
Extreme difficulty of the technique
Policy implications for Australia
So that’s what I’ll talk about today. In the process of that I’ll explain the basics of stem cell research and its aspirations, and I’ll also glance onto the policy implications for Australia.
For starters, let me refresh you knowledge of the general concepts.
Stem Cells 101
Ordinary cells like skin cellshave a limited ability to proliferate. A skin stem cell (a type of adult stem cell) can reproduce itself to a limited extent but it can only give rise to skin cells.
An embryonic stem cell, by contrast,can reproduce indefinitely. And it can give rise to any cell type of the body. In other words it is pluripotent.
In most cases, embryonic stem cells are sourced from surplus test-tube embryos. They are derived at about five days when the embryo has become a hollow 100 cell ball known as a blastocyst . Inside the ball is a lump of 30 cells known as the inner cell mass(ICM). It will give rise to all the tissues of the body as well as some extraembryonic tissues.
Bear in mind the embryo is still at a very primitive state. Any cell of the inner cell mass is just as likely to become placenta as person.
Once the ICM is cultured, most of the cells do start specializing or differentiating, becoming elongated muscle –like cells or stringy neuron-like cells. These types of cells have already committed to particular fates and will soon stop proliferating and die. What scientists are looking for is the rare cell colonies composed of round, dark , plump cells that shows no sign of changing. To get them requires a person with a mono-maniacal bent.
The changeling cellswill tend to corrupt the pristine ones. So the mono-maniacneedsto monitor the culture round the clock. Once the colony shows signs of differentiation, the still pristine cells need to be plucked away to safety and onto a fresh batch of culture medium and feeder cells (fibroblasts).
Once they have established a stem cell line (one embryo gives one embryonic stem cell line)— they need totest them to see of they are truly pluripotent. They do that by injecting them into a rat and seeing if they form a teratoma (a cancerous mass that is a mess of different tissues).
SLIDE3: SKIN CELLS, SKIN STEM CELL, EMBRYONIC STEM CELL.
SLIDE 4: BLASTOCYST, ICM, CULTURE METHOD
That’s the procedure for generating embryonic stem cells from surplus IVF (in vitro fertilization or test-tube embryo)embryos.
Embryonic stem cells generated this way, have the capacity to form any tissue of the body. However in the culture dish it turns out some tissues are much easier to make than others.
SLIDE 5: DIFFICULTY SCALE FOR MAKING DIFFERENT TISSUES
EASIER: BRAIN AND CNS
MEDIUM: HEART MUSCLE, BLOOD CELLS
HARD: PANCREAS, LIVER
Counter-intuitively brain tissue is the easiest! Beating heart cells are also relatively easy. Blood cells are doable.
The most difficult tissues are the inner organ tissues. Innormal development, the pancreas, lungs and liver all sprout from the gut. So the goal is to coax embryonic stem cells to make primitive gut-like tissue known as endoderm, and then to find the factors that will make them follow different forks along this path. That’s why last year, a rather enigmatic headline hit the news media. “Scientists make endoderm.” It really made me giggle. (Aside story: They thought they could already make pancreas cells by using the brain cell recipe because the cells seemed to be making insulin. But it turned out these were brain cells making insulin! Moral of the story: just because it quacks like a duck doesn’t mean it really is a duck).
SLIDE 6: TISSUE GRAFTS: THE GREAT HOPE:
DOPAMINE PRODUCING BRAIN CELLS FOR PARKINSON’S DISEASE
HEART TISSUE TO PATCH UP FAULTY HEARTS,
INSULIN- PRODUCING CELLS FOR A CHILD WITH DIABETES.
MOTOR NEURONES FOR SPINAL CORD INJURIES
So with embryonic stem cells, the great hope is that theywill eventually be trained to provide replacement tissues. For instance, dopamine-producing brain cells for Parkinson’s disease, or heart tissue to patch up faulty hearts, or insulin- producing cells for a child with diabetes.
SLIDE 7
THERE IS A LONG WAY TO GO:
1. TRAINING THE CELLS TO MAKE THE RIGHT TISSUES.
2. MAKING SURE TISSUES FOR GRAFTING DON’T CAUSE CANCER
3. THESE TISSUES WOULD BE FOREIGN, AND LIKE ANY FOREIGN GRAFT MIGHT BE REJECTED BY THE IMMUNE SYSTEM. (THOUGH PERHAPS NOT).
THAT IS WHY THERE WAS THE GREAT EXCITEMENT ABOUT THE WORK FROM KOREA.
The Korean team claimed they could both clone a human embryo from a person’s skin cells, and from that embryo derive embryonic stem cells. Any tissues derived from such cells would be perfectly matched to the person who provided the skin cells. Think twenty years in the future, and the technique could supply diabetic kids with replacement pancreas cells, without having to use life threatening drugs to suppress their immune systems.
Little wonder the world wentgaga over Hwang’s results.
No-one else in the world had been able to do it for humans. Although in 2000 Megan Munsie from Stem Cell Sciences in Melbourne was the first person in the world to demonstrate therapeutic cloning as a proof of concept in mice. (SEE COSMOS, ISSUE 3 SEP 2005 )
SLIDE 8: Therapeutic cloning
The technique of cloning involves reprogramming a specialist cell to a primordial state, a reboot if you like. The primordial state for a cell, is the early embryo. This is how we began: the fertilized egg programmed to build a human embryo.
SLIDE 9:To do it, the researchers remove the nucleus (which carries the genetic instructions) out of the specialist cell, and introduce it into an egg whose own nucleus has been ejected. It all lends itself nicely to a computer metaphor: the software of the egg reboots the introduced nucleus. The hybrid egg now starts developing as an embryo with the genetic instructions of the donor’s nucleus. In cattle cloning that embryo is implanted into the womb of a surrogate mother, and about ten percent of the time, a cow will be born. You also get a lot of very sick and deformed cows. So reproductive cloning is bad idea for people. (SEE COSMOS, ISSUE 6 DEC 2005). However in therapeutic cloning, the goal is to derive embryonic stem cells from the clone. So the embryo is allowed to develop for five days to reach the blastocyst stage and then stem cells are cultivated from it.
Hwang announced that he had done this first in 2004. It was published in one of the two most prestigious scientific magazines in the world: Science. And it attracted enormous fanfare. But after the fanfare died down, scientists realized it was a very qualified success!
It turns out that the cells of our body are not all equal when it comes to clonability.
The commoncloning fantasy had it that a skin cell would provide the starting material for a clone. Or a nose if you remember “Sleeper” by Woody Allan. But mammal cloners typically had little success with skin cells. Where they did have success was with a cell called a cumulus cell, a diminutive cell that forms clusters on the outside of eggs. That’s how the first clonedmouse “Cumulina” got her name. Megan Munsie also had success using Cumulus cells as the source of the nucleus to be reprogrammed.
Hwang also reported his only success with cloning a cumulus cells. Moreover it had come from one woman, and this same woman had also supplied the egg for cloning.
SLIDE 10: HWANG’S 2004 SCIENCE PAPER
In other words, a woman—let’s call her Betty-- donated her own egg and her own cumulus cell. The Koreans, removed the nucleus of the cumulus cell, and placed it into her egg to produce an embryo that was a clone of Betty. From that embryo they derived embryonic stem cells.
The publication raised a lot of questions:
WOULD IT ONLY WORK FOR CUMULUS CELLS?’’
WOULD IT ONLY WORK WHEN A WOMAN PROVIDED BOTH DONOR NUCLEUS AND EGG?
- Was it really the product of a clone? To prove that a cell line is a clone, it’s necessary to show two things. Recall that a clone is a hybrid produced by the nucleus of the donor cell, and the cytoplasm of the egg. The cytoplasm of the egg contains mitochondria which possess peculiar genes of their own, so-called mitochondrial genes. So proof normally requires first : to show that the nuclear DNA is identical to the skin donor’s nuclear DNAand second: that the mitochondrial DNA is identical to the mitochondrial DNA of the egg donor.
But in this case, the egg and the nucleus came from the same person, so it was not possible to prove that the cell line was derived from a clone. How else then could one derive embryonic stem cells that matched Betty? Well, it is possible that Betty’s egg was triggered to undergo parthenogenesis—where the chromosomes of the egg duplicate themselves to make a full set, and then go on to form an embryo. This could have happened if Betty’s egg had not been rid of its nucleus after all, (it’s not always possible to be sure), and if the injected nucleus failed to reboot. However with all the tweaking and poking of the egg, that could have triggered the parthenogenetic response. This has certainly been seen in mice.
- The second problem with the paper was: why this was the only success he reported? Was it possible that cloning was not going to be successful unless you used the egg and somatic cells of the same person?
- Was it possible that cloning was only going to work from cumulus cells?
Finally, to get his one success, Hwang had used 242 human eggs. Cloning was clearly very difficult, and wasteful. For the single success with “Betty”, a couple of hundred attempts using eggs from other women and presumably other donor cells had failed.
So while there was a lot of excitement over Hwang’s publication, especially in the media--he was Time’s Man of the year and widely feted--to scientists, the success was very qualified, and it was really unclear as to how useful the technique would be.
SLIDE 11 SCIENCE 2005 PAPER
But all those reservations were blown away by the publication in May 2005.
Skin cells
Men, women, children
Astonishingly efficient 17eggs per cell line-
It was just as Woody Allen had imagined: Hwang reported being able to use a mere scrape of people’s skin, to clone embryonic stem cells for them. And this time the successfully cloned included men, women and children.
Moreover, in the hands of his team, the technique was remarkable efficient! On average it took only 17 eggs to get one successfully created embryonic stem cell line. Astonishing!
It was also astonishing that no-one doubted Hwang.
Slide 12: Korean work ethic: 24/7
Supportive policy and funding
Steel chopsticks
People attributed the phenomenal success to the Korean work ethic (his people worked 24/7); that they were not stymied by government policy and they were very well funded. (Over the years they’d received over $30 million!!!!). And not least the technical prowessof Koreans. Wielding a fine needle to suck out the nucleus of a human egg, and then reinjecting the nucleus of another cell, is quite a display of manual dexterity. Hwang joked this was something trained into Koreans from a lifetime of wielding metal chopsticks!
Now we know it was all a fraud.
There’s an interesting tale to tell, in how Hwang was nailed. It involved some extraordinary scientific sleuthing by, of all things, a TV current affairs program that put together a posse ofTV producers and local scientists(whistle blowers). ( See April issue of Cosmos.)
The scientific smoking guns
So in the Science 2005 paper, Hwang claimed he had used skin cells to clone embryonic stem cells for nine patients.
SLIDE 13 - 16:Proofs:
Are they embryonic stem cells?
- Visual ascertainment—do they look like embryonic stem cells lines? SLIP UP
- Do they carry the right marker proteins? TRUST
- Do they form teratomas?
SLIDES 17 & 18:Are they clones?
- Compare DNA fingerprints of donor skin cells and stem cell lines.
- Should be similar not identical
Ethical implications: global and local
SLIDE 19:
People opposed to stemcell research have long bandied about nightmare scenarios that women would be exploitedfor their eggs, and that scientists couldn’t be trusted: let them do therapeutic cloning today; tomorrow it will be to make babies. The Korean affair brought all these nightmares to life.
Women were exploited. They were paid for their egg; some became ill (ovarian hyperstimulation syndrome) and still went on to donate again. Scientists behaved in a deceitful fashion. Besides the scientific and ethical misconduct, about a million dollars of money remains unaccounted for.
The scientists behaved badly. Does it mean the technique should be banned?
We don’t ban the Catholic Church because of paedophile priests. We make laws and are more vigilant. The Church of science also has its fallen priests; the same response applies. That is that legislation should be enacted that allows scientific progress, while guarding against clear ethical transgressions.
So what about the ethics of all this?
Those opposed to embryonic stem cell research try to hijack the moral high ground claiming that research that destroys a senseless human embryo is unethical.
Many doctors/scientists say that their ethical compass guides them towards finding cures of suffering people. From their point of view,it is morally more correct to worry about the rights of suffering people than the rights of an embryo (whether it is a surplus test-tube embryo destined to be thrown away or a clone embryo).
There is no winning this moral battle; and according to Paul Komiesaroff, a professor of Medical Ethics at MonashUniversity, we shouldn’t even try. Most certainly as he told the recent Lockhart review (which addressed whether Australia should raise its ban on therapeutic cloning, and whether our existing stem cell legislation was robust), there should not be a ban on the technique. Rather it should be left to individual ethics committees to slog it out on a case by case basis. As he told me, “it should be hard work; there are no short cuts.”
Future of therapeutic cloning (TC).
SLIDES 20 – 22:
It is however clear that TC is going to be far harder than was recently thought. At present the idea of cloned embryonic stem cells for individual patients seems pretty remote. Hwang used over two thousand human eggs and failed to success getting even one cloned cell line!
When researchers find a rebooting factor than can replace a human egg this will again become a possibility.
Meanwhile a fresh field of contenders are vying for the trophy of being the first to achieve therapeutic cloning. It is still a very worthy goal for the purposes of making a limited number of cloned cell lines from people with degenerative disease. For instance a cell line from a child with Spinal Muscular Atrophy (a disease that progressively paralyses the child)would serve as a model of that disease, and allow scientists to rapidly test hundreds of thousands of drugs to find one which will mitigate the course of the disease. It’s like having hundreds of thousands of model patients to treat like guinea pigs.
The debate has been dismayingly unscientific
SLIDE 23:
- “Pick and choose” notions of research are misguided—you can’t predict the course of research, serendipity in science is the norm.
- Furfies—adult stem cells have more runs on the board. Yes but only in long- established areas like bone marrow transplants and skin grafts. This is technology that’s been used for 50 years, and has never cured anyone of diabetes or Parkinson’s disease.
- Novel applications remain unproven and highly contentious. Eg, heart and Parkinson's Disease (Swedish researcher Patrik Brundin’s poor student, spent two years trying to make brain cells out of bone marrow cells, with no luck).
- Common sense: in exploration success comes from following as many paths as possible
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