Cloning a Cure – How Close Are We?

Original article by Dr Adam Hedgecoe

Updated February 2004

Imagine you need a transplant organ. A sample of your cells, perhaps from a cheek swab, will be taken to obtain some of your DNA (ie your genes). Your genes will then be inserted into a human egg that has had its own DNA removed. An electric pulse will zap the egg and trigger embryonic development by cell division and all of the resulting cells will carry your genes. At about the 100-cell mark the embryo, which is a clone of you, will be used to harvest cells that will serve as a starter stock for growing replacement tissue for you.

In February 2004, Woo Suk Hwang from Seoul National University in South Korea reported that he has successfully harvested cloned cells from a cloned embryo. These cells have now been growing in culture for more than a year, and are ready and waiting to heal the donor whenever they may be needed.

Why do it?

The major benefit of these kind of cloned 'stem cells' over traditional donor transplants, is that they carry your genes. This means that your immune system won't reject the new tissue. Therapeutic cloning promises to massively increase the number of diseases that can be cured with transplant surgery. Spinal injuries, Parkinson's disease and heart disease are just some.

Crucial to therapeutic cloning are the stem cells that are present in early stage embryos. These are the cells that Woo Suk Hwang (among others) believes can be harvested to save lives. Stem cells are unlike other body cells in that they carry the potential to produce any one of the 200 different kinds of body cell. After embryonic development, most cells lose this ability, a skin cell, for example, can't change into a liver cell. The hard bit is to coax the stem cells into becoming skin cells, liver cells or whatever is needed. This is a crucial stage that Hwang has successfully demonstrated in mice, where grafted stem cells were able to differentiate into muscle, bone and cartilage tissues.

Tissue rejection

At the moment, organ transplants can be quite a touch and go affair. Finding a compatible donor is not always easy, especially if time is short for the patient. And even then there can be serious problems of transplant rejection. Our bodies are built to recognise and attack anything foreign. Any cells which don't match our own genetic makeup come under fire from the immune system.

In order to prevent organ rejection, new transplant patients are faced with having to take debilitating drugs that suppress the immune system and leave them open to infections. But therapeutic cloning offers a means of providing tissue that is genetically compatible with the patient's own. In this case, the transplanted organ is not recognised as foreign and not attacked by the immune system.

The incurables

The holy grail of cloning and stem cell research must be certain kinds of degenerative diseases like Parkinson's, Alzheimer's, diabetes and spinal cord injuries. All so far incurable by medical science. Insulin-producing cells could be introduced into the pancreas of diabetics, vital hormone-producing cells may help brain recovery in Parkinson's and Alzheimer's patients, and new nerve cells may heal spinal cord injuries.

Indeed, it's been claimed that almost no area of medicine would be unaffected by these developments. Eventually cloned stem cells might be encouraged to hoover up unwanted cholesterol, regenerate damaged heart muscle, replace tired liver cells – the list is endless. And the beauty of it is that the stem cells trigger a huge immune response.

Christopher Reeves, the former Superman actor, has sadly passed away, but in his lifetime he was a fervent advocate for therapeutic cloning. He was paralysed from the neck down in a serious horseriding accident in 1995. Although Reeves was aware that the science might be too young to benefit him, his determined support has done much to bring debates about stem cell research into the public arena.

Has it been done yet?

Scientists at a US company called Advanced Cell Technology (ACT) were successful early on in the race to clone human embryos for stem cell research. They produced two early stage cloned embryos, one of four cells and one of six. In both cases growth then stopped – a phenomenon that animal cloners have got used to. In animals, cloning is still a fairly hit and miss affair that is largely a numbers game. Keeping the clones alive and dividing once the egg has been activated is tricky and it can take way over 100 eggs to get one viable clone.

Neither of the embryos produced by ACT were large enough to harvest stem cells. The company have also produced early human embryos through a process called parthenogenesis. Here they triggered embryonic development in a 'virgin' egg that was not fertilised or fiddled with in any way. They have reported some success with this procedure and they are still working on it.

Human embryos generated only from eggs do offer an advantage to therapeutic cloners. Egg cells contain DNA in the nucleus, this makes up the vast majority of the genetic material of the cell. It is the nucleus that is removed to make way for new DNA in the cloning process. But the egg also carries a small quota of genes (or DNA) in tiny structures called mitochondria. When a clone is grown (animal or human) it carries the nuclear genes from the adult 'clonee' and mitochondrial genes from the egg cell donor. The concern is that the few genes from the egg cell donor may trigger an immune response in prospective patients. So far, early experiments in cattle would seem to allay these fears, but scientists still think that 'egg-only embryos' might be safer as a way of producing transplant tissue.

So far, scientists have had altogether more success with stem cell technology in animals than they have in humans. Transferring the technology to human cells has proven problematic. Woo Suk Hwang has had the most success so far. But from a starting point of 242 eggs, Hwang and his group managed a yield of only 30 cloned embryos, and from these they were able to harvest stem cells from only one embryo. So whilst hopes ride high, it seems that many more man-hours of hard science will be required before stem cell cloning is perfected.

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 – 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?

Cloning FAQs
Answers to some commonly posed questions. Including the difference between the two types of cloning and what stem cell therapy could do for us.

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'.

Find out more

Channel 4 is not responsible for the content of third party sites

Websites

Roslin Institute, Edinburgh
www.roslin.ac.uk
Scientists here created the first ever clone of an adult mammal in 1997, Dolly the sheep. Almost all the research is published in the public domain. The 'public interest' pages offer summaries of published reports on mammalian cloning, the technology, its progress, ethics, plus discussion papers, press articles and an image library.

Clonaid
www.clonaid.com
This private US organisation has pledged to be the first to clone an adult human and offers a range of services, including Clonapet, promising the possibility of cloning a deceased family pet. Note that the organisation was set up by Rael, spiritual leader of the Raelian religious cult movement and the world's largest UFO-related organisation.

Advanced Cell Technology
www.advancedcell.com
Website of the company claiming to have cloned the first human embryo.

New Scientist
www.newscientist.com/hottopics/cloning
Up-to-date articles and information on the ongoing cloning debate.

Pondering the Ethics and Science of Stem Cells
www.upenn.edu/gazette/0302/0302gaz1.html
Article on the ethical issues raised by stem cell research.

Bioethics.net
http://bioethics.net/cloning.php
Site by the Amercian Journal of Bioethics. News and features to suit all levels of knowledge.

Primer on ethics and human cloning
www.actionbioscience.org/biotech/mcgee.html
Article, on the Action Bioscience website, introducing the key issues in human cloning and ethics.

Genetics
www.channel4.com/genetics
Channel 4 site accompanying Sir John Sulston's Royal Institution Christmas Lectures. Includes the first 'artificial life experiment' designed for the general public.

Books

	A Clone of your Own? by Arlene Judith Klotzko (Oxford University Press, 2002) The writer-in-residence at the Science Museum takes a look at the science and ethics of cloning. Get this book
	The Cloning Sourcebook by Arlene Judith Klotzko (Oxford University Press, 2001) Aimed at increasing public understanding of cloning. Discusses animal cloning since the birth of Dolly the Sheep and the questions raised by cloning for society. Get this book
	The Impact of the Gene: From Mendel's peas to designer babies by Colin Tudge (Hill & Wang, 2001) In the mid-19th century a friar, Mendel, discovered the basic laws of heredity. Tudge examines the influence of Mendel's ideas, considering the evolution of genetics as a science, and addressing questions of ethics, the public's fears about cloning and eugenics. Get this book
	The Second Creation: The age of scientific control by the scientists who cloned Dolly by Ian Wilmut, Keith Campbell and Colin Tudge (Headline, 2001) Recounts not just how Dolly was created, but also the techniques for her predecessors who were cloned from embryo cells. It explains the scientific reasons behind the research, and discusses where this technology will lead and the ethical issues that have been raised. Get this book
The Secrets of Life: Genes and genetics from evolution to engineering (Channel 4, 2001) £4.95 (inc P&P) Cheque or postal order payable to Channel 4 Television, send to: The Secrets of Life, PO Box 400, Wetherby, LS23 7LG or phone + 44 (0) 8701 246 444 Colour booklet, published to accompany the Channel 4 screening of the Royal Institution Christmas Lectures. Follows Sir John Sulston's journey from the beginnings of life to the latest developments in biotechnology and into the future. Discusses ethics of cloning.

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