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Cloning FAQs
What's the difference between reproductive cloning and embryonic stem cell cloning?
News that a lab in the US cloned a human embryo has been hailed by some as a medical breakthrough that will soon allow cloned embryonic stem cells to cure diseases such as Parkinson's and Alzheimer's. Other people believe that it is a dangerous step towards the realisation of full reproductive cloning – ie living, breathing human clones.
The basic technique used for embryonic stem cell cloning is the same as for reproductive cloning. The nucleus of a donor egg is removed and replaced with the nucleus from the person being cloned. After being treated with a chemical cocktail the embryo starts to divide. It is at this point that the differences arise.
In reproductive cloning, the embryo is then implanted into a womb. It has to be implanted before the embryo has reached the blastocyst stage – the point where it has divided into around 100 cells. The embryo has to be implanted at this stage to allow the cells to specialise into all the different tissues necessary for life, including the placenta which supports the embryo as it develops.
In embryonic stem cell cloning, the embryo is never implanted into a womb. It is allowed to reach the blastocyst stage in a petri dish and in doing so is prevented from ever becoming a viable whole person, the cells will never be able to specialise as placenta tissue. When the embryo has become a blastocyst, stem cells can be extracted and made to grow into the specific cells that are needed, eg nerve, heart muscle or insulin-producing cells.
How do I find out about stem cell application? I am primarily interested in its application for cancer patients.
There are serious hopes for the treatment of cancer with stem cell therapy. However, the technology is in its infancy. The best thing to do is contact companies and clinicians that are conducting trials and see what they suggest.
For a general introduction to clinical trials of stem cell therapy in the treatment of cancer try CancerBACUP. The American website Medline has lots of links covering topics on stem cell and stem cell transplantation ranging from the latest news to clinical trials.
With reference to stem cell technology, what does the future hold for the treatment of heart disease?
In the field of stem cell research, it's really very hard to predict what the future holds, not only because technology is inherently hard to predict, but also because there are many ethical and political considerations concerned. Even if the relevant technology becomes available, governments and the public might decide they don't want to use it.
But there is a lot of interesting research going on at the moment concerning heart disease. The main bone of contention is whether heart muscle cells can be made to grow in an already fully grown, but damaged, heart. Conventional medical wisdom has it that they can't. However, there are a couple of studies in the last year that suggest otherwise.
Bone marrow stem cells have been directed to damaged hearts in mice, and they grow there. You can find more information on this at the American Society of Hematology.
The most exciting development is that cells from a human donor will grow in a recipient with some good effect – read about it on the New York Medical College website.
For general information, the US National Institutes of Health have a primer on the subject of stem cells in which they talk about heart disease.
Any news on clinical trials being carried out in the UK on the regeneration of cartilage in arthritic knee and hip joints using stem cells.
Clinical trials on stem cell therapy to treat rheumatoid arthritis are currently underway at Leeds General Infirmary. So far, six patients have had stem cell therapy with some success. All but one of the six has improved and only one has relapsed. At this stage these therapies are reserved for people with very severe rheumatoid arthritis who are not responding to other treatments.
You can find out more about the trials on the Arthritis Research Campaign site.
Professor Paul Emery is in charge of the Leeds study, you can find out more about him on the University of Leeds Medical School website.
Read more on stem cell therapy from the Roslin Institute.
My mother has multiple sclerosis (MS) and is in a wheelchair. Could she benefit from any of the stem cell treatments, how could she take part in trials?
There have been preliminary trials in the US on stem cell treatment for MS patients. The treatment was developed by doctors at the University of Washington Medical Centre in Seattle and involves taking tissue samples from the patients, separating out the stem cells and returning them to the body after the patient has received chemotherapy. The idea behind this is that the chemotherapy removes the patient's immune cells leaving the patient with an immune system untouched by the abnormalities caused by MS. The returning stem cells will then mature and hopefully fight any other cells that attack the immune system and contribute to MS.
For more information check out the National Multiple Sclerosis Society website.
My mother is 82 years old. She had a stroke nearly three years ago which paralyzed her left side. She was very fit and able before. Maybe stem cell therapy can help her. Are there any clinical trials on stem cell research to be initiated either here in Ireland or in the UK?
Some types of stem cells are able to differentiate into the different types of brain cells when they are injected into the brain. These cells have the potential to restore function to parts of the brain that are damaged.
Reneuron are a UK company hoping to start clinical trials soon, though they have recently had a technical problem that might delay trials. It might be worth contacting them directly to see when they are intending to begin human trials.
Other trials involve using drugs that cause stem cells in the brain to multiply and differentiate to restore lost or damaged tissue.
What impact will cloning and genetics have on personal identity?
Our looks, our personalities and our minds are all a product not just of our genes but also of our environment – before and after birth.
Identical twins are essentially clones of one another – they have exactly the same genes but can sometimes be quite different in looks and personality. No-one would say that you didn't have your own identity because you shared it with a twin!
Of course that's just the bare bones of the argument. The new genetics has many implications – there are controversies over parents cloning a child to provide bone marrow for a sick sibling or growing organs in animals for transplant into humans.
Find out what the Vatican thinks of it all.
Do human clones exist already as has been claimed this year?
There have indeed been reports of human cloning already taking place. Severino Antinori, the Italian fertility specialist, made a passing remark that three women were already pregnant with human clones. But one of his ex-colleagues has gone on record in the US saying that this is unlikely.
The organisation Clonaid have claimed that two baby clones have already been born. But this has never been verified and seems unlikely.
An American team from Advanced Cell Technology did clone a human embryo in 2001, but only to the six-cell stage, as part of their research into therapeutic cloning. There was never any intention of implanting the clone and allowing it to develop into a fully fledged human being.
Kentucky fertility specialist Dr Panayiotis Zavos currently has a 10-cell cloned embryo sitting in a freezer that he plans to plant into a surrogate mother.
Is it true that Dolly the cloned sheep aged faster than the 'original Dolly'? If so, how come?
This is a tricky question, and impossible to answer definitively. Certainly, if Dolly really aged faster than she should, that could spell real trouble for the future of cloning. The evidence for her speedy ageing is perhaps compelling but not utterly convincing.
We do know two things. Firstly, Dolly had arthritis, in the knee and in the hip of the left hind leg. What's more, it's rather uncommon (but not unheard of) for this to occur in a sheep as young as Dolly (about five years old).
Secondly, Dolly had unusually short telomeres. Telomeres are the 'caps' of DNA that sit at either end of a chromosome. A chromosome is a very large packet of DNA, but despite its size, it's still just one strand with two ends. DNA is generally a very stable molecule, but its ends are vulnerable – they slowly decay, causing the DNA strand to gradually get shorter. This is a problem, because if a lot of DNA is lost, some of that might be important DNA – genes that code for proteins that do important jobs.
So, telomeres are repetitive bits of DNA that only serve to cap the end. Although they decay with time, the cell is usually able to replace them. But telomeres tend to get shorter with age. This has led many scientists to believe that there is a link between telomeres and age. Indeed there probably is, but it will be sometime and take many man-hours of research to work out exactly how telomeres effect the ageing process.
Now, if we look at the cloning process, it's actually easy to work out why Dolly's telomeres were short. The 'original Dolly', as you put it, had cells taken from her at the age of six or so. By this time, her telomeres were getting slightly shorter. These cells were then used to create the new Dolly, and the telomeres were not regenerated during the cloning process. So when new Dolly was born, she inherited the telomeres of a six-year-old sheep.
So if we looked at new Dolly's DNA, it would look like the DNA of an 11-year-old sheep (more or less). The question is, does that mean Dolly hit sheep 'old age' faster than a normal sheep? Was this arthritis the sign of the old age?
The answer is, we don't know. Dolly was just one cloned sheep – perhaps she had arthritis for a totally different reason.
You may also be interested in these other Channel 4 articles
The Race to Make a Human
The story behind the mavericks striving to be first past the post in the human cloning game.
Cloning Ourselves – How Close Are We?
The truth behind recent cloning claims, the reasons for doing it and the dangers involved.
Cloning Ourselves – Ethical Dilemmas
The potential to make a living clone is already with us, here are the ethical arguments laid bare.
Cloning a Cure – How Close Are We?
How cloned human embryos could heal the sick, including the methods and the motivation.
Cloning a Cure – Ethical Dilemmas
A way of healing the sick that involves destroying tiny human embryos. Is it worth the cost?
Immortality – Hype or Hope?
How cloned stem cells will leave no branch of medicine untouched. How long would you like to live for?
Dolly
The life and times of Dolly the sheep, the first ever cloned mammal.
Severino Antinori biography
The independent fertility specialist who wants to clone whole human beings.
Francis Galton biography
Introduction to the life and work of the man known as the 'Father of Eugenics'.
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