As new cures for degenerative diseases seem increasingly possible, BBC Two's If... Cloning Could Cure Us takes a look at the controversial issue of embryonic stem cell therapy.
Does this type of research and potential treatment herald a medical revolution, which will save countless lives?
Or is it just one step too far in an ethical minefield?
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When are people going to get "it?"
We have been progressing for centuries. Some progressions have been successful, others not.
This one allows us to progress with the aid of a foetus that wasn't "meant" to make it. Don't close the door on religion. Close it on the politicians that use it as their platform.
Jonathan Vervaet, Vancouver, B.C., Canada
All human life is sacrosanct from the moment of conception.
The human embryo is a human being and will never become anything other than what it already is. If we do not accord respect to the weakest, smallest and most vulnerable of human beings then the lives of us all are in jeopardy.
John Scotson (Dr)
Any way of saving a life is a good thing. I'm sure anyone who has lost anyone close would have loved for them to be still here.
This stem cell therapy is a cure, as is a cold medicine, a flu jab or radiotherapy.
Where do we draw the line at what is and isn't playing God? Surely God, being the giver of life would be happy to see humans working tirelessly to preserve it.
Geoff Agnew, Larne, Northern Ireland
This is in response to Mr. Paul's (from Oxford) comment.
It all boils down to the fact that all the advancement of science compared to "poor" performance of God, hasn't gone any where out of the system God has created.
I don't see any polymer based embryos nor any silicon blood cells.
Far beyond being moral or immoral, it's more of a question that are we wise enough to know every implication that we cause with each breakthrough in genetics? If we are lured to believe that we know everything, we practically defy the advancement of science itself.
Mansoor, Lahore, Pakistan
Disabled people do not need a cure. We are valuable human beings as we are. This debate, alongside much of medical thinking and practice, highlights what people believe is wrong with the disabled and relegates them to being in need of a cure. Whether you can walk or not doesn't make you any less of a person. We want and can have a perfectly good life without taking life away from someone else.
Gill Gerhardi, Aylesbury, UK
I think that is unfair to hamper the advancement of medical science, when so could be cured of their afflictions. Is it right to save the life of something not born in place of curing those who are suffering, because of an embryo that might not even make it?
Conor, Cork, Ireland
Why on earth are people still pursuing the idea of using stem cells derived from embryos? Haven't any of these so-called scientists heard of using stem cells from umbilical cord blood? This has been proven to save lives and doesn't raise any moral, religious or ethical issues. Simple really!
Kimberly Hollands, Toronto, Canada
If... Cloning Could Cure Us was excellent: a compelling drama combined with serious scientific information and ethical debate.
Huw Thomas, Carmarthen, Wales
This has to be a triumph for medicine, patients and science. I'm sure we had this debate when we first has blood transfusions and I remember the debate when heart transplants were first performed. Science and medicine moves on and treatments for diseases and conditions improve. The people who say "no" shouldn't deny other patients the choice to research, life and health, especially if they are not the patient suffering.
Scott Wallace, UK/Japan
This process takes a life to save/improve a life and that is totally and utterly wrong. Regardless of their size, state of consciousness or appearance, they are ALIVE. When I first found out that I was pregnant, even though it was just a tiny embryo inside me, as far as I was concerned it was a life, a "baby". The thought of someone manipulating and killing the equivalent of this in a petri-dish somewhere sickens me to the core and should not be allowed.
Playing God? If God was any good, scientists would not have to develop techniques to improve on God's poor efforts.
Paul Ed, Oxford
Life begins at the moment of conception. Everything is present in that very first cell to determine how that person will be - the colour of hair, height - all the genetic material is contained from the beginning of life. Every one of us started life this way so it is completely wrong to say that life doesn't begin until later in the pre-birth process. For this reason, it is wrong to use ANY embryos of whatever age for experimentation.
I am not against science and its development per se but I am completely against using life with potential to satisfy the whims of scientists who appear to have few moral values.
Karen Bruin, York
Embryonic stem cells have a very poor therapeutic record. They have never been used to treat/cure any human patient suffering from any disease, and all reference to their therapeutic potential is entirely speculative.
Even in research on animals, embryonic stem cells have performed badly. Few studies show any benefit to animals injected with them. And a wealth of research shows that animals receiving them are likely to develop cancer as a direct consequence.
Dr Lena Wilkinson, Newcastle
The argument that all life is precious seems somewhat ridiculous when people are more concerned about a ball of cells and its "viability" than the millions around the world who die needlessly each year because of mankind's cruelty to itself.
This is a tremendous chance, unprecedented in human history, for the human condition to be cured. Let's hope we can manage to get it through the courts and help people before we wipe ourselves out with our other preoccupation of killing each other.
Russ, Coventry, UK
I agree with Ben Hayford's statement. He is religious, yet he sees the obvious benefits for mankind. Also Malcolm from Warsaw summed it up rather nicely.
In the end, a ball of cells is a ball of cells. A foetus is a foetus, and a human is a human. If you create a ball of cells in the lab, to extract cells that can potentially cure a lot of people, and then destroy said cells, what is wrong with that? The cells will never develop into a human as they are not going to placed in a womb. End of story.
Robb Dunphy, Dublin, Ireland
I personally feel that allowing stem cell research to go ahead would be wrong in most cases. Where do we draw the line in exploiting human life? Is it any different to saying that one life is more valuable than another? I think that it is about time we accepted that accidents do happen, and live with the consequences, instead of using a potential human life to resolve these problems.
Zoe Johnson, Exeter, UK
It's horrifying that this debate is so confused.
Your correspondents talk about "stem cells", mostly without qualification. They then assume that all stem cells come from embryos and that these offer the only real chance of a cure. In fact, all real cures so far have come from ADULT stem cells - to which no-one has any ethical objection. NO cures have so far come from embryonic stem cells.
Tim Roberts, Bracknell, UK
I believe that the recent advances in medicine are vital for the development of mankind. Although it is impossible to study something without changing it, it is vital that we realise that stem cells save lives, and must be tested in a safe legal environment, if they are to succeed and be safe.
If the "embryos" being discussed are created without the intention of ever being implanted in a womb, then I believe the argument that a potential human life is being destroyed is completely false as these "embryos" can never develop.
John, Penzance, UK
At the end of the day, the needs of the less fortunate and immuno-compromised far outweigh those of a 19-day-old embryo. It is important that we allow research to continue and that we develop the cures that are necessary to those who are already suffering.
Omar Rahman, Swiss Cottage, London
I have recently been diagnosed as having young onset Parkinson's Disease.
Many early attempts to treat this condition using embryo cells have been disastrous. Yet this is constantly put forward as one of the promised cures, at the same time as adult stem cells are providing fewer problems and greater promise then originally imagined. Why are we pushing so hard to destroy embryos and playing down the promise of adult stem cells?
Anthony Deeney, Glasgow
Pure rational science must prevail over the irrational prejudices of moralists. Incredible religious doctrine must give way to the inevitable advancement of knowledge.
Life should NEVER be created for spare parts for an existing life. Life is very precious and each and every one of us would agree with that, even at a basic level, considering how precious we believe ourselves to be. If we continue to do research with human life used as an expendable by-product of it, ie. destroying life to cure it, we will only have ourselves to blame for the consequences this will have for our own and our ancestors' future.
James Molloy, Glasgow
I believe that the doctor was acting in the best interests of the patient and is therefore innocent. If the patient does not object, and is willing to take any risk, where is the harm? Abortions are carried out daily at much later dates than that of 19 days.
Linda Moore, Stramshall, Uttoxeter, England
If there is good evidence that other sources of stem cells, not involving the destruction of embryos, can produce cures - as has been reported recently in the media - we should put more money into this research.
H Shaw, Oxford
An embryo is not alive until brainwave activity is detected. This is long after the 19 days mentioned here. Yes, this technique could well produced abnormalities, but all progress has a price. And yes, the price is worth it here.
Oh, and apparently, 81% of you agree with me. Victory for progression.
Edward Miles, Crewe, Cheshire
These aren't conscious beings hooked up to electrodes and being tortured in the name of science, they're a gateway to the advancement of medicine and helping human life. This is within human capability and can be used to aid, therefore I can't possibly see it as an evil. What about those who need it most? Are they evil for wanting it?
Garrett, Palm Bay, Florida, US
In answer to your question, Evelyn Kong, yes: you were less of a person when you were a newly conceived embryo. You were then a collection of cells with no conscious brain yet developed.
How can anyone consider that an embryo less than 14 days old has the same right to life as does a fully developed human being (of any age)? This is an absurd point of view which ignores the real suffering of real people. A ball of cells does not equal a life.
When we recognise that a human embryo is exactly that - human - then we begin to understand just how precious and fragile life is. Stem cell research - for sure, but don't just choose the most vulnerable of humanity to find solutions for the rest of us. "No" to mucking about with embryos, and "yes" to using tissue from adults and cord blood.
Suzanne O'Rourke, Whangarei, New Zealand
My husband has the terminal and degenerative Motor Neurone Disease, one of the diseases that may be cured by stem cell research.
To those who oppose it I would say - you may change your mind if you had to watch someone that you love suffering with this hideously cruel disease when there was no cure nor treatment to halt it. Watch someone you love eventually living in a glass coffin, only able to move their eyes and tell me your reasons again. I believe God loves us all and he gave us the intelligence and conscience to do the right thing for all humanity.
May McGarrigle, Welling, Kent
Josephine Quintavalle's argument seems to be based on embryos being destroyed after harvesting stem cells.
It looks to me as if most (all?) of them are unused embryos created as part of a course of IVF treatment which would have been destroyed anyway.
Does this imply that because embryos are destroyed then IVF treatment should also be banned? I suffer from Type I diabetes and if cells from an embryo that would have been destroyed anyway would save thousands like me from four times daily injections then I think it would be worthwhile.
Peter Johnston, Lochgelly, Fife
"If....we could cure them" appears not to have consulted those who such research could impact - disabled people.
We aren't all for this kind of research. I believe it will set up a two-tier disability movement where those who can be cured will be seen as more desirable than those of us who can't - or don't want - to be "cured".
As a result, the disabled people's movement will be damaged because the authorities may mistakenly believe that further legislative moves towards civil rights for disabled people will be unnecessary, and we will remain second-class citizens. Some people's Utopia is others' Dystopia.
Chris Page, Letchworrth, UK
I am a first year biochemistry student, and stem cells have been an area of interest of mine for some time, with their potential application to the paralysed, blind, and those with degenerative nervous diseases.
I recently learned that one of my best friends and her little sister, on top of both being born partially deaf, will be going blind in the not too distant future. They are 19 and 14 respectively. They both have a condition called Usher's disease, and stem cells could stop them from ever losing their sight.
I am a dedicated Christian, and anyone who claims that stem cell research and medical application is playing God, must either be ignorant, or wish to play God themselves. Surely everyone has the right to sight?
Ben Hayford, Southampton, Hampshire, UK
I may only be nine years old but I generally have a strong point of view on things, politically.
Cloning may not be very religiously correct but I'm sure God would prefer people to live, having been cloned, than to lose their life, when they could have survived, having been cloned.
Chloe, Luton, England
I have MS and from what I understand this therapy has the potential to greatly benefit myself and other MS sufferers to the point that our symptoms are reversed.
MS is just one of the diseases this could benefit. It is a revolutionary and necessary step forward that should definitely be given the go ahead.
Esme Noot, Portsmouth, UK
Were we trying to play God when we invented the wheel, learned how to make fire, discovered electricity or penicillin?
No, we were not. We were discovering what was already there, whether you believe it was put there by a supernatural being or not. We certainly should carry out a risk analysis, but don't ridicule such a study by bringing medieval myths into it.
Ed, Aberdeen, Scotland
There is always much bitterness in this debate, but we must remember that we all want the same thing - cures for these dreadful diseases.
Nobody argues with adult stem cell research so the issue comes down to the use of embryos.
I believe that the end does not justify the means and the impact on society that life can be created for a use in something else will far outweigh the benefits these embryos provide.
Paul, London, UK
Human embryos have no consciousness or self awareness. However they are a gift that can cure, prolong life or improve the quality of life of real living people.
Religious freedom is not the freedom to impose your own religious beliefs on others or to deny treatment that would otherwise make a real difference.
Any innovation in science, especially in the medical profession, is always welcome. I myself work in the medical field and I am definitely against stem cell research.
The end simply does not justify the means. In order to save one life, one has to sacrifice one, or even a few lives in the process. Each life is precious. Is an embryo of 14 days of "age" any different from an embryo less than 14 days old?
Where do you draw the line? When does life start? All of us have gone through the same process. Was I less of a human or person when I was conceived than I am now?
Evelyn Kong, London, England