A team of scientists in South Korea say they have created stem cells which match the genes of patients.
Researchers now need to find out how the stem cells can be made to reproduce specific kinds of tissue in order to treat diseases such as diabetes and Parkinson's
In a separate development, UK scientists from Newcastle University have become the first to produce a cloned human embryo from which stem cells can be harvested.
What is your reaction to the major advances in stem cell research? Do you think it is an important medical breakthrough or is it unethical to carry out this type of research?
This debate is now closed. You can read a selection of your comments below.
Sad case histories make for bad laws. Suffering is part and parcel of human existence. No matter what advances science makes it only puts off a little the inevitable outcome: Death! Let us try to relieve human suffering as far as possible respecting the natural law.
Maureen, Abingdon, UK
I think that everyone should be willing to accept that when the time is right we may need clones for anyone who might need help in times of suffering.
Moriah, White Plains,New York, USA
I believe the potential beneficial outcome of this research overrides the conservative views which label this research as unethical. It has been my experience that those who have the belief such research is immoral or otherwise distasteful, do not have the misfortune of watching helplessly while a loved one suffers from a degenerative condition. Consider the following: Is it unethical to steal bread to feed your starving children? On the same token, is it just as unethical to pursue research which might save your suffering child?
Timothy Brown, Palm Coast, USA
Oh please. It seems to me that most of the people who claim that cloning is wrong are under the impression that we're going to be mass-producing Hitlers. We're talking about cells, not people. And all that "but it's potentially a human" stuff is nonsense. So is every menstruation a murder? I don't think so. And you'll notice that people who are against stem cell research aren't the ones with diabetes. They're not the ones who're watching a loved one being destroyed by Alzheimer's. Just ask yourself this: If my child were dying in need of a bone marrow transplant, would I even stop to think about it?
Steve, Oxford, UK
Great news for diabetics like me who hope for a cure!
V S S SARMA, Dubai, UAE
Those who are talking of God in scientific research have lost their minds. Leave God alone. He is so powerful that he will fight for himself. Scientists must push their research about cells as far as they can. This will help to discover how to get rid of HIV.
Justin Hategekimana, Pittsburgh, USA
Considering the outcry about genetically modified plants, it is surprising so many people find GM humans acceptable. I have sympathy with those looking for cures for genetic diseases (I include myself in this group), however I have the feeling this could be a poisoned chalice if not managed correctly. Depending on your point of view this is either playing God or tampering with evolution. Either way this is science that should be considered carefully.
Peter, Ferryhill, England
It really upsets me when people dismiss this as unethical or wrong when it will have no direct effect on their lives. Last June, a week after my 19th birthday, I was diagnosed with Type 1 diabetes. Over the past year I have been getting used to a different lifestyle; four injections a day, careful planning and loss of spontaneity. While I still have a very fulfilled and enjoyable life I wonder - why me? From the day I was diagnosed I have known that this is a life-long disease, however I never thought that I would suffer from it for more than 10-20 years. The advances being made are fantastic and I can't wait for the day that I could be 'cured'. The worst thing about hearing of these amazing advances is the reaction from people who say it is wrong. If they could only understand firsthand what a difference it could make to somebody like me I'm sure they could put aside their grievances and realise that it can only be a positive thing.
Becca, Bath, UK
As someone who's been both (insulin dependent) diabetic and paralysed from the waist down for the past 13 years, the day when stem cell research bears fruit cannot come soon enough. I adapted long ago to life in a wheelchair, but the constant knowledge of the fact that diabetes will lead to my premature death is most a unpleasant thing to live with. Whilst objectors have a right to air their concerns, they do not have the right to deny me the chance to watch my baby daughter grow to become a woman and to meet my grandchildren, especially when they base their objections on religious beliefs that I do not and can not share.
Howard Watson, York, UK
The possibilities for good are immense, but the possibilities for bad are unimaginable. So far, humanity has not been capable to control the bad uses of scientific discoveries. We do not need one more uncontrolled and uncontrollable avenue.
Sophia Goulimis, London
I am alive because five years ago I received a stem cell transplant. I have friends with diabetes, and cannot wait until the day when the promising research underway using stem cell as the basis of a cure for diabetes, makes a cure for this diseases widely available. Those who for so-called religious and ethical reasons oppose stem cell research, are engaging in mumbo-jumbo. Thank goodness the indications are they will not prevail
C. Alexander Brown, Ottawa, Canada
Every day the Northern countries spend more and more money to find more and more ways to make our lives easier. And yet, millions upon millions of people live in preventable squalor and lack of basic necessities. Can't we try harder to make the lives of all humans a little more comfortable before we try to cure the elite populations of this world of a few more ailments?
J Sagawa, Tokyo
It does not matter if stem cell research is banned or not, there will always be countries and clinics and doctors who will carry on regardless of the law. Why should criminals, the military and the mega rich be the only ones to profit from this important work?
Richard Read, London, UK
A batch of undifferentiated cells cannot be considered a human life. Doctors around the world are hoping that stem cells can save their patients from suffering. There is no moral dilemma because there is no life to destroy, only a life to be saved.
Daniel Lowell, Austin, TX
A definite step in the right direction but should be used only for treatment of diseases. Stem cell research should be encouraged but cloning human beings would be unethical.
Chandra, Brussels, Belgium
Today one of my sons is in hospital recovering from a necessary bone marrow transplant because of a rare genetic disease. If this moves us forward towards the day when there is a true genetic cure then surely we can only welcome it.
David Hartley, Romsey, UK
Having seen the cruel effects of Alzheimer's on my father, and in the knowledge that it is sometimes hereditary, I must admit a selfish interest in the development of a cure! I don't acknowledge a group of cells as a human being: there is no sentience there, and no sensation is possible, because of the lack of a nervous system. How does such a collection of cells have higher status, and more rights than an adult human being who, at least initially, is aware they are about to lose their faculties, their personality, their senses and ultimately their life?
Chas Knight, Duxford, UK
Scientists play God again. The West goes to extreme lengths to prolong life for the wealthy whilst millions in the Third World die of starvation, malaria and other diseases of poverty that don't require unethical high tech solutions.
David Mullen, UK
As a diabetic I welcome ANY hope for a cure. I am 55 years old and would like to see my grandchildren grow up into adults.
Ronald McKenzie, London, UK
The breakthrough represents yet another 'nail in the coffin' of our current way of life. The implications are that dying organs can be replaced, human life can be extended, who says we can't live to 150 with further scientific breakthroughs? Imagine then the social upheaval of this change to humanity, if everybody has access, or even worse should access be restricted by ability to pay!
Rik Harding, Manchester, England
Stem cell research DOES represent an important medical advance BUT it should be used in accordance with natural law. Cloning human beings is wholly unethical. It is always wrong to use any human being as a means to an end. Yet today people appear to have lost sight of this fact.
Anne-Marie Walker, Haddenham, UK
Before people criticise stem cell research, maybe they should put themselves in the position of someone who desperately needs that science to help their medical needs - they'd soon change their tune I'm sure. Stem cell research needs careful management for sure, but the benefits are a giant technological leap forward for the human race. We've got this far, why shouldn't we go further?
Jim, Norwich, UK
I'm not against this for any real moral or ethical reasons, but I do have a problem with those who claim we should stop playing God, when these are the same people who think IVF should be freely available for everyone.
Jennifer, Netherlands, ex-UK
It is clear that there is a lot of misunderstanding around this area, judging by the comments here. Even the use of the word 'embryo' is misleading, since it can create the impression of one of those cute little tadpoley things that turn into babies. What they are actually dealing with is microscopic bundles of cells, numbering far, far less than the number of cells you dislodge every single time you brush your hand against your face.
Katherine, London, UK
So how many embryo's are destroyed every day in the name IVF? Why is OK to destroy a bundle of human cells to satisfy someone's biological clock but not to save or improve the lives of many?
Mark, Ottawa, Canada
This technology will be developed whether or not certain countries embrace it. It seems wiser to support and monitor its uses instead of pretending it doesn't exist. President Bush rejects stem cell research saying it is wrong to destroy life in order to save life, yet his policy in Iraq seems to run counter to this logic.
Patrick Collins, Denver, Colorado
The world population in 1970 was just under 4 billion. Today it is 6.5 billion. In 2037 it will be 10 billion. Another medical breakthrough is good, but will ultimately lead to this planet being consumed and burnt out by humans. Probably before we can move onto another planet.
Scott, Weston-Super-Mare, England
I feel as though we are treading on dangerous ground. It is very sad that people have so many awful illnesses, but our leaders should look very hard into how this step could be damaging in the future. It seems as though this technology will be pushed to the point where cloning people won't be considered such a bad thing.
Matthew Dolman, Isle of Man
Those who object to this research on ethical grounds, or the fear that somebody might turn a profit in saving lives, are entitled to their opinion. Meanwhile, those of us who put the health of our families above cells in a Petri dish will continue to fund and hope for real cures to real problems. It is the failure to prevent harm to conscious people that is unethical.
Matt, Oakland, California, USA
If it alleviates the suffering of some people then that has to be good.
Mark Floden, Dubai
This debate is focusing on the rights and wrongs of cloning, which seems besides the point. We have a mechanism for determining whether the population of a country deems a decision to be appropriate to be brought into law: it's called democracy. Notwithstanding that a president is elected, the right of presidential veto is fundamentally in conflict with the central tenets of democracy, leaving way too much power in the hands of one man.
Bruce, New York, USA
I think it is a great achievement for mankind. As to those who object morally (read religiously) to this issue, I would say a human being is a lot more than a ball of cells.
Darcy Vieira, Sao Paulo, BrazilIan Sharp, Bath
Clones are just the same as twins. I don't know what all the controversy is about. every time science takes a new step ignorant people get frightened and say it's unethical - look at people's reaction to IVF when it first became used. Everyone accepts it now.
Veronica Bamfield, Poole
It is wrong to reproduce and experiment on human beings (whatever their stage of life) for the benefit of others. All life is of equal value, and none should ever be sacrificed for others. The prospects of human cloning are truly diabolical.
Marilena Cairns, Rome, Italy
As a parent of a child with Type 1 diabetes I feel this breakthrough is wonderful news. To see your child constantly have to inject himself with insulin and do blood tests to stay alive is a heartbreaking, and we are never free of the condition. So many others would also benefit from this stem cell work who have incurable diseases. This news must give thousands of sick people new hope.
David Parker, Southampton
I am perplexed that many of us seem to find "destroying human beings" in this way so objectionable, yet express no such view on guns, motor vehicles, starvation and disease. All of these kill hundreds of thousands worldwide per day.
This is a very important medical advance and an inevitable one. Now is the time for calm, rational thought on how best to have a measure of control and regulation over this potentially life - in the sense of all life on the planet - altering technology.
Clive, Milwaukee, USA
The point of this research is not to create perfect replica humans, but to aid in the protection and recovery of the human condition. Those that object to these developments on the grounds of ethics may be forced to ask themselves the question that when there are diseases such as cancer and HIV spreading throughout the world, perhaps it is unethical not to do all we can to help those that are suffering. Genetic research is here, its advancement is inevitable, we cannot sacrifice those that are alive and in pain for those that are not even yet born.
James Reynolds, Dublin, Ireland
Oh good. Millions of pounds will now be poured into developing cures to keep people alive even longer in the west, which should help us with that pesky 'how are we going to tackle this surplus of earths resources' problem we have. Meanwhile, in Africa....
I'm a first year medical student and know that this research has the potential to save many lives and stop suffering from debilitating diseases. I hope that when I graduate we will be starting to use this awesome therapy. I don't see how people with any sense of humanity can argue against it.
Faye, Staffordshire, United Kingdom
Just because you can doesn't mean you should. No legislation will prevent this being exploited. From this point there is no going back! I'm no Luddite but, nevertheless, a sad day for humanity in my opinion
Terence Summers, Andover England
Its about time, this is one aspect of scientific progression that we cannot afford to ignore or prevent because of a small minority of people.
Emma, Forres, Scotland
I have a friend with Parkinson's disease whose quality of life is almost non-existent. He sits in the same chair day in a day out hardly able to move and in constant pain with this crippling disease. He has suffered like many other sufferers with this disease for over ten years. Stem cell research is his, and may other sufferers, only hope of ever having a normal life and anyone who opposes it should spend a couple of days with a sufferer, it will change their opinion. It is a terrible disease. How can you be pro life and deny a Parkinson's disease sufferer a dignified life?
P Polain, London
I have a young son with diabetes. Complications of diabetes include blindness, heart disease, kidney disease, nerve damage leading to infections and amputations. There are many other complications. I welcome any developments into stem cell research and hope that a treatment, for this condition and many others, will soon be available to prevent so much suffering.
I am grateful for this breakthrough - it will help so many heart-breaking situations which can now be corrected in babies and others with this move forward in medical science. Blessings to those determined scientists.
Mavis Fielding, Middlesbrough, England
Already we hear the cries of "unethical." Unethical by what standard? Either they get their ethics from a religious leader or their feelings, anything other than using their minds. This explains their utter hostility to any scientific progress. It's a slap in their faces when they see man conquering nature and, so that they won't ever be reminded of what brilliance man's mind can achieve, they claim success is "unethical" and clamour to regulate it out of existence. This is moral inversion at its height.
Nic Garvey, London, UK
While some legislatures may outlaw human cloning, there will always be others that won't. These nations will become the new leaders of modern medical science, forging ahead with new advanced technologies. The "ethics debate" is almost rendered irrelevant in this respect; rather, it is a question of world power in the sciences. Thus, human cloning is essentially inevitable, and we would do well to embrace its great prospects.
Robert Yang, California, USA
Cloning embryos to produce stem cells is a smoke screen. Scientists are well aware that stem cells can be just as effectively reproduced by other methods without the need to produce embryos. This is blind arrogance and ultimately man playing God. We have seen recently that politicians are prepared to lie to achieve their ultimate goal. To what ends will these techniques be used for in the future? Can we really trust the state? This has the 'Brave New World' finger prints all over it.
Mark Malik, Warsaw, Poland
The science isn't what worries me. It's that we don't have the social mechanisms to determine how this and other cutting-edge technologies can best be regulated. The field is wide open for profiteers, ego-trippers, fraudsters and general basket cases. This will end in tears.
Richard Bradshaw, Stokesley, N Yorkshire, England
David Appleton is wrong. A ball of cells can not become a human being without a host - the mother.
Paul Weaver, Twyford, Berks
It's disgusting, just creating and destroying human beings in an early stage of life. We should have more respect.
Nicky, London, UK
Hopefully this heralds a new era in medical science. It just needs the public to be better educated about these techniques before they will accept them. I for one have no qualms about any ethical issues, scientists have been responsible in the past, and I am sure cloned 'organ banks' will never be utilised. As for the eggs being potential lives, they weren't fertilised before they were taken from the women, so clearly they were just going to released during her period, and never become a life.
Rob, York, England
When a sperm cell breaks through and fuses to an egg cell life has begun. This ball of cells can, if left alone, become a fully fledged human being. Scientists are blinded by ambition to cure the next disease, they've betrayed life itself and God in whose image it was created.
David Appleton, Staines, UK
Excellent research, a natural progression, the objections are the same as always when scientific progress takes another step forward. If the objectors had their way we would still not have organ transplants, science has to experiment to advance and I am positive that even the objectors will grab the eventual medical benefits without question.
Arthur, Derby, UK
Scientifically there is no prospect of curing Parkinson's, simply slowing it down. Many of us who have had loved ones with Parkinson's would not thank science for creating more years of suffering by manipulating human life at the other end. This is ghoulishness driven by potential medical business profits.
Jon, Totteridge, England
This is a very important step forward for medicine, and has the potential to cure many illnesses that are today incurable. I only hope that no church or UN resolution tries to impose its views on us and stop our research. I personally am quite relaxed at this development, and do not think it is 'playing god'. We have always striven to conquer nature, and each time life has become better.
Joseph, Lincoln, England
We need to be careful. While this can be used to help others, the potential for abuse also exists.
Chris, Glasgow, Scotland
Knowledge is good and it has helped us improve our lives and society. However, everything that can be done should not just be done simply because the knowledge of it exists. While cloning could help cure sicknesses which were thought incurable, it could also raise moral and social issues. If a human being can be duplicated (cloned) it could increase the world's problem of security and terrorism.
Anthony Esenwa, Lagos, Nigeria
This technology can save lives. There should be no debate. The more research done, the more we can understand and the better the techniques become. The ethical debate is that you would be taking a life. Life is defined partially as sentience. A few cells are not sentient.
Brian Simpson, Aberdeen
I am proud that the UK is one of the countries that are leading the way in this area of science and I'd love to see the fruition of such research being made to cure health problems. I'd much rather see research being done open and clearly for understanding and improving life. With open scientific experiments and the scientific debates that goes with this in this country means I can follow the progress with hope that people close to me, and I, would benefit and improve life quality for them and me.
Kyle Sterry, Newcastle, UK
Mary Shelley's prophetic novel Frankenstein has finally become a reality. Mankind's misguided attempts at creating a better world are going to end in disaster. How dare we carve up life at its earliest stages in the name of saving life at its later stages. The powerful are manipulating the weakest. Its scary.
Michael Williams, Liverpool
There's no way of stopping fundamental research. So we might as well come to terms with it - and legislate, if necessary, as to ethical use.
David Ball, Wokingham, UK
Whilst cloning is still legal, there will always be scientists who will investigate its therapeutic potential. In this case however, an unfertilised ovum was used - this ovum was never destined to become an embryo, nor could it have become one after being injected with genetic material. I wish these pro-life activists would at least try and understand the science before damaging their credibility with flawed claims of immorality.
Adam, Philadelphia, USA
The beginning of the end. What with insurance companies eager to get their hands on the ID card data, which will show you medical history, anybody benefiting from this treatment and "non perfect" health history will find themselves un-insurable.
Robert Bahrani, London, UK
A fantastic development. Quite why people seem to think of cloning as such a taboo subject is entirely beyond me - nobody denies that care is required to ensure that there are no unpleasant complications, but if it can save lives then I welcome it whole-heartedly. Let the religious objectors refrain from ever taking advantage of these new developments, if they're so stridently opposed, but leave rational people alone.
Paul Christopher, Exeter, UK
If the stem cells derived from this cloning have the same problems as dolly the sheep's cells, then they will be subject to premature aging and all kinds of other malfunctions. Won't this make them useless anyway. Man should stop interfering with things that he pretends to understand, but doesn't really have a clue about. "A little knowledge is a dangerous thing".
Chris, Telford, UK
The benefits of stem cell research far outweigh the disadvantages. Opponents of this technology would soon have different thoughts when new treatments are available that may save their, or someone close, life.
Stewart, Toronto, Canada
Utterly abhorrent. I think it is absurd that we are fiddling with humanity in this way when we have not yet exhausted (or even begun to use in some cases) existing ethical alternatives.
Patrick Leahy, Cambridge, UK
I have a hard time with campaigners against human embryo cloning who argue that no potential human life should be destroyed. Do they have any qualms about the hundreds of eggs that will be released and lost naturally during a woman's lifetime? If stem cell research can be developed and used to save people's lives I am all in favour of it. Shouldn't we be thinking about the real lives rather than the potential ones?
Well done an excellent example of British science. Congratulations to Professor Murdock and his team.
Chris, Bristol, UK
If history is anything to go by then this will go much further than just the cloning of embryos and should worry every one of us.
Graham Smith, London, UK
This really seems so unethical to me. Isn't it amazing that when a woman is pregnant she calls it a baby but scientists can call it an embryo and do what they like. Where does it stop? Do we continue until we have a fully cloned human and is it then bred just for spare parts? Perhaps we should stop here.
Lyn, Worthing, Sussex