Jackie: Welcome to BBC Learning English dot com and Insight Plus - a series first broadcast in 2001 that looks at the language of issues you hear about in the news. How far should science go to help the sick and the suffering? Today on Insight Plus, Lyse Doucet looks into the cloning debate.
Lyse: Cloning is copying, it can be applied to many things but here we are talking about copy of a living organism. We are all made from billions of cells, and at the centre of each one are the instructions - the blueprint - for building our bodies which is stored in the form of a chemical called DNA. There are two types of cloning, reproductive cloning （生殖克隆）where a new baby would be created or therapeutic cloning（治疗性克隆）, that’s about copying just some of the cells. Therapeutic cloning concentrates on some special cells called stem cells - they’re the powerfully adaptable 'master cells'. Opinion is deeply divided about whether or not we should develop this technology. The BBC World Service has been reporting the developments made in this most sensitive of issues, we hear first from Dr Robin Lovell-Badge of Britain's Medical Research Council.
ClipThese cells exist naturally in the body and they are there to replace cells that are lost through natural processes, so you lose skin cells all the time, you lose cells from your intestines（肠） - your guts - and there are stem cells in the brain to replace a few cells which are lost. And normally the stem cells divide just the right amount to maintain the organ in a good state. But in the cases where there's accidental damage（意外损害） or a disease which affects a tissue or an organ, then quite frequently the stem cells aren't able to divide fast enough to replace the damaged tissue. So it's hoped that by growing them in a test tube, if you like, that they can be now used to replace lost cells in a personLyse: As Dr Robin Lovell-Badge explained, stem cells regenerate（更新） tissue. They repair and maintain our kidneys, liver and other organs. By introducing new stem cells into the body, scientists hope to renew damaged tissue and even fight illnesses such as heart disease and Parkinson's - a disease of the brain.
In 1998, American scientists succeeded in isolating and culturing - growing - stem cells. They unlocked their potential for medical research and treatment. In future stem cells could be a vital tool in the war to keep everyone well and healthy.
Doctors know that adult stem cells can develop into different cell types. In Sweden, for example, the neural（神经的） cells - cells taken from the brain of adult mice - have been used to generate kidney, heart and liver cells. But researchers aren’t sure whether adult stem cells are as perfectly adaptable as those found in embryos - newly created lives. When an egg is fertilised（施肥） by a sperm, it forms a ball of cells, any of them can develop into almost any cell in the body. These 'master' cells - embryonic stem cells - are at the centre of much of the current research.
Why is the procedure is causing so much anxiety? Well, one way of harvesting - collecting -stem cells is to actually create embryosm, through a process known as therapeutic cloning. It’s based on a technique pioneered at the Roslin Institute in Edinburgh, in 1996, Dolly the sheep was born. Dolly was the first mammal cloned from an adult cell - a nucleus taken from an adult sheep cell and inserted into an empty egg. The egg's development into an embryo was triggered by a revolutionary new technique which makes it possible to clone existing animals - and it could be used to produce human clones.
Once we have perfect copies of ourselves we’ll be able to repair and renew faulty parts of our body. The transplant techniques we have now sometimes fail - in the US, for example, twelve percent of patients receiving organs from dead donors die within a year of the operation. That’s partly because our bodies work hard to reject anything alien that is grafted （接枝，贪污）onto it - anything that is imported into the body, even if it’s a new lung, a liver or a new heart. Chronic （慢性的）rejection, which usually occurs three or four years after the operation, causes even more deaths. In Britain, heart transplant survival rates fall from 81% in the first year to 65% of patients surviving five years after the operation. Professor Richard Gardner believes therapeutic cloning could solve this problem.
ClipAs with all organ transplants, just using the stem cells that were available you would not always have a perfect match and you'd have to treat patients with drugs to stop the graft being rejected. And that is why people are talking about going beyond this. And that would be taking a human egg, putting the nucleus（核） from the patient into that egg and instead of fertilising it, activating it to grow just to the stage where you can derive（派生，导出） embryonic stem cells, because they would be genetically identical with the patient and you wouldn't have the problem of graft rejection.
Lyse: That was Professor Richard Gardner, chairman of Britain’s Royal Society Working Group on Therapeutic Cloning. He has great hopes for medical research in this field. Let’s take for example the case of a male patient who needs a heart transplant. Professor Gardner believes that one day it may be possible to extract the nucleus of a cell from the patient to briefly clone an embryo of him and them to use the embryo's stem cells to treat him. So the patient’s body would then accept stem cells which perfectly matched his genetic makeup instead of rejecting a transplanted donor organ or a tissue graft. In future cell nuclear transfer could even be used to create a personalised bank of stem cells, they could be stored and used as and when the patient needs them.
ClipWhat we're looking for in the future is to get away from the situation where virtually all those requiring a graft have to wait until someone else dies to provide a healthy organ or tissue for them. The stem cells（干细胞） offer the prospect of building up banks of cells that you can then grow them and make them become whatever cell type the patient requires.
Lyse: But treatments like these remain a distant prospect. When scientists understand and can control the development of stem cells, activating their growth into nerve cells, heart cells or blood cells, will they be able to use them in the treatment of disease.
Stem cell research is the subject of today’s Insight Plus from the BBC World Service - it’s your guide to the language and background to the stories that stay in the news. Some of the greatest medical advances of the 21st century may result from（起因于） stem cell research. The development and ethics of therapeutic cloning will attract the attention of the world’s media for some time to come.
And governments around the world also face the ethical dilemmas（道德困境） provoked by this field. Should scientists be allowed to harvest stem cells from embryos? Should the cloning of human embryos be permitted, even if reproductive cloning, the creation and birth of cloned human beings, is outlawed（失去法律保护的）? Very young embryos are now legally used in fertility research in many countries. The unwanted embryos used by some of the American scientists who first cultured stem cells came from fertility clinics. But in the United States public funds cannot be used for any research which involves killing embryos.
Britain is one of the first countries to consider legislation which would allow therapeutic cloning and stem cell research on embryos up to 14 days old. A committee headed by Professor Liam Donaldson, Britain’s Chief Medical Officer, has spent a year preparing a report on stem cell research for the British Government. It’s a debate that’s being heard around the world.
ClipThe conclusions of the committee were that stem cells have an enormous potential to create new forms of treatment for diseases which are currently incurable… major, major medical potential. We need medical research to see if this potential can be realised. The potential benefits in this balancing exercise outweigh some of the concerns and would be justified by the potential benefits for future generations of patients - we are talking about here research at this stage, not treatment.
Lyse: The committee say that the benefits outweigh the ethical concerns. They believe research should continue, should go forward, but only if strict rules limit, or regulate, the research. Professor Donaldson would like to see the law tightened to ensure no-one is allowed to create a human being.
ClipMost important of all and without room for any ambiguity（不明确的，含糊的） or doubt, that the creation of a human being through cloning should not be permitted under any circumstances and is illegal at the moment and should remain illegal, reinforced by even more legislation.
Lyse: Around the world, many who believe that an embryo, however young, is a human life remain deeply concerned by the new research. Dr Sandy Thomas from Britain’s ethics organisation, the Nuffield Council on Bioethics, explains their concerns.
ClipPeople are concerned of course about how we should use embryos, if at all we should use embryos for research. In some countries embryo research of any kind is prohibited. In others, a very limited amount of embryo research is allowed. And the reason that there are ethical concerns here is that obviously an embryo has the potential to become a human being and we therefore should accord it some respect. The problem for many people is how much respect? So much respect that we do no research at all on a one or two day old ball of cells, or for example, respect at some perhaps slightly later line when we would not allow research, perhaps fourteen days, as in the UK.
Lyse:Many who oppose embryo research believe scientists should only work with adult stem cells. But scientists argue that even if therapeutic cloning was banned, embryo research would still be needed to help them to understand how stem cells function.
Today we've been discussing stem cell research and the ethics of therapeutic cloning. One solution may lie in the pioneering technology used to create Dolly the sheep. In this case, scientists reprogrammed the adult cell used to clone her. The nucleus of the cell was taken to a near embryonic state before it was inserted into an empty egg cell, it was then allowed to develop again as an embryo. One day, scientists may be able to extract and 'reprogram' patient's cells before they re-insert them into the body, there they would begin to regenerate damaged tissue and organs. Such cells would never be implanted into an egg, the creation and destruction of an embryo would be avoided.
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