Basics
Introduction
Stem cells are master cells of the human body which can do one of two things. They can either simply make copies of themselves, or they can produce other types of specialised cells. The very early embryo contains stem cells which slowly specialise to produce all the cells of the body. Adult cells can now also be reprogrammed in the laboratory so that they return to an embryonic-like state and can be used to make all kinds of specialised cells.
The medical importance of stem cells
Stem cells taken from embryos or created by reprogramming adult cells would not be injected directly into the adult body because of a risk that they might go on copying themselves and become cancerous. But they can be induced under special conditions in the laboratory to grow into (in principle) any type of cell in the human body. This would give a ready source of cells to replace ones that normally can’t be replaced once damaged, such as heart and nerve cells.
Take a patient with a spinal cord injury. They might be helped to recover if nerve cells were injected into the spinal cord. Nerve cells might also be able to slow or even stop Parkinson’s disease. Pancreatic cells might bring diabetes under control, and so on. The potential is clearly enormous, but at this early stage in the research it is difficult to know how many of these hopes will indeed become viable therapies. To extract stem cells from embryos is very controversial and the techniques for reprogramming cells are very new. It is not yet known whether reprogrammed cells will be able to do everything that embryo-derived cells can.
Info cards
Stem cells are master cells of the human body which are able either to produce copies of themselves, or to produce other, specialised types of cells.
In the embryo, stem cells gradually specialise to produce all the cells of the body.
In adult tissue, stem cells exist to keep regenerating particular body cells during the person’s life.
extracted from:
• Embryos
• Some adult tissues (e.g. bone marrow)
• Placental cord blood
• Amniotic liquid
Scientists are able to isolate stem cells and keep them indefinitely in the laboratory. They can induce some stem cells to turn into specialised cells, e.g. nerve, skin, blood cells.
Stem cells - or specialised cells derived from them - might be able to slow or even stop some degenerative diseases, repair damaged tissues, or cure burns.
Degenerative diseases can affect people of any age, from childhood through to old age. They include:
• Parkinson’s
• diabetes
• cystic fibrosis
• multiple sclerosis
• muscular dystrophy
• hepatitis
• osteoporosis
Research in this field is at an early stage. One day, stem cells may lead to cell replacement therapies, but it is unknown how effective these would be.
Embryonic stem cells are usually taken from embryos created by in vitro fertilization. The cells are taken when the embryo is about a week old; it has 30 - 150 undifferentiated cells and measures 0.14 millimetres. The embryo is then destroyed.
Embryos used in research are mostly ‘surplus’ from clinical treatments like IVF. Some countries permit them to be created specifically for research.
In IVF, ‘surplus’ embryos arise when more embryos are created than a couple wants to implant. Currently there are hundreds of thousands of these embryos stored in Europe and destined to destruction.
Stem cells are found in adult tissues such as bone marrow and the brain. They are few in number and are often difficult to obtain.
Adult stem cells usually produce only the few types of cells that are related to that particular part of the body (e.g. bone marrow producing different types of blood cells but not liver cells).
Induced pluripotent stem cells (iPS cells) are very similar to embryonic stem cells. They are made by reprogramming adult cells and can be used to grow all the different specialised cells of the body. A whole mouse can be grown from iPS cells combined with host embryo cells.
Stem cells are found in placental cord blood at birth. They are more abundant than adult blood stem cells, easier to obtain, and may pose fewer rejection risks. However, recent research suggests they cause cancer when used to treat disease.
If placental cord blood cells could be turned into other cell types, cord blood could be frozen at birth and ‘banked’, to be available for cell therapy in later life. Therapies of this kind are still a long way off at the moment, and may prove not to be practicable because of technical hurdles and cost.
In human development the embryo implants into the womb about 7 days after fertilization at which time the first steps toward cell differentiation begin. The first stages of the nervous system appear after 14 days. This is the legal limit for research on embryos.
Before the 14 day limit for research an embryo may split into twins. About half of all embryos, or perhaps even more, abort naturally because of spontaneous genetic abnormalities such as extra chromosomes in their DNA.
Some EU countries permit no embryo stem cell research. Some allow it only with surplus IVF embryos. The UK allows embryos to be created for stem cell research, including creating cloned embryos.
In the UK it is illegal to create a cloned human baby (reproductive cloning), but it is legal to make a cloned human embryo and allow it to grow up to the 14 day limit in order to make stem cells (therapeutic cloning). The difference is in the purpose not the process.
Human-animal hybrid embryos can be created by removing the genetic material from an animal egg and replacing it with human DNA. In 2008 some researchers in the UK were given permission to create this kind of hybrid for research.
Therapeutic cloning aims to stop a patient’s body from rejecting stem cells as foreign tissue. Cells are taken from a cloned embryo, created from the patient’s own cells.
In therapeutic cloning, cells would be taken from a patient’s body and fused with a human egg that has had its DNA removed. This creates a cloned embryo of the patient.
Week 24 is the limit on abortions for social reasons. Abortion for medical reasons is legal until full term (weeks 38-40).
In 2004 a United Nations ban on cloning collapsed. All nations support a ban on reproductive cloning (making a baby using cloning techniques), but some wanted to outlaw research with cloned embryos, which others allow.
The foetus develops its brain structure by week 10. The limit for abortion for social reasons is 24 weeks, when the foetus starts to respond to light, sound and other sensory stimuli. The legal limit for research on the embryo is however 14 days.
Scientists can now manipulate cells taken from adult skin cells to return them to an embryonic state in the laboratory. This is a much easier and more efficient procedure than cloning.
Before 40 days after fertilisation, Jewish law does not consider the embryo as “human life”. Therefore, taking cells from an embryo is morally neutral.
- Against: human life begins from the one-cell stage.
- In favour: according to Saint Tomas d’Aquino’s developmental approach: God introduces the human soul progressively in the embryo: The vegetative soul, then the sensitive soul and, then the human soul.
It covers a wide range of views from a total opposition to embryonic stem cell research to a position in favour of therapeutic cloning.
According to Muslim law, the moment when an embryo receives a soul does not occur until the fourth month of pregnancy. Embryonic stem cell research is morally neutral according to mainstream Muslim Law.
Issue cards
If the power of embryonic stem cells can be harnessed and we are not prevented by opponents, we have the potential to treat a wide range of currently untreatable fatal diseases.
When does human life begin?
What status should we give to a 14 day old embryo:
• a cluster of cells;
• a potential human being;
• a form of life;
• fully human life, with all the rights a human baby has?
Is the prospect of treating currently terminal illnesses justification enough for stem cell research using human embryos?
In embryonic stem cell research, embryos under 14 days old are destroyed. Some people argue it is unacceptable to destroy a new life, even to save the life of an ill person. Where does the balance lie?
How important are moral values of the past? Should we still be bound by them or should we adjust our moral values as times change?
Are deeply rooted human values being sacrificed under pressure from scientific innovations? Or can we find a good balance?
Is it wrong to create embryos just for stem cell research? What about using surplus embryos from IVF or embryo selection that will be destroyed otherwise?
If we create embryos simply to use them as a source of stem cells is it treating embryos like a resource for getting spare parts? If so, is this okay or not?
Should we be allowing IVF (in vitro fertilisation or ‘test tube’ babies) and/or PGD (selecting embryos to avoid serious genetic diseases)?
Does the creation and use of cloned embryos and reprogrammed cells bring us nearer to creating cloned human babies?
Should we do research with cloned embryos now? Or should we wait until we have thoroughly explored the potential of stem cells taken from spare IVF embryos or from adult tissue? Should the ability to reprogram cells change our view on using embryonic stem cells?
Should we place moral limits on science? For example, only allow non-embryonic stem cell research? How might that affect the progress of research? Does that make a difference to your moral standpoint?
Are the 14 day limit on embryo research and the 24 week limit on abortion based on science or moral distinctions, or are they just arbitrary legal boundaries?
A UN ban on human cloning is proposed. Should society seek to limit certain applications of science? Or will it always be done, if it can be done?
Who should be involved in developing stem cell technologies and therapies - government, private corporations, foundations or trusts, academic institutions?
Should the research money for all stem cell research be reallocated to the foreign aid budget, to increase basic healthcare in poor countries?
Will these technologies make the global divide between rich and poor better or worse?
Adult stem cells are already used in treatments, e.g. in bone marrow transplants for leukaemia. All stem cell research can help improve understanding of how stem cells work. Does this affect your view of embryonic stem cell research?
Are we falsely raising expectations of cures for people suffering from degenerative diseases?
How far are we justified in doing controversial research with embryos to help an ageing population live longer? What if the quality of very old age cannot be improved much?
Is there eventually a limit to medical research? Is there a point where we have to accept our mortality and the reality of suffering?
How democratic is policy making on these issues and how democratic should it be?
Even in medicine, researchers must not just make up the rules to suit their aims. Society has a right to say what should or should not be researched. How far should this be taken? How much control over research should society have?
Stem cell research has great potential for treating serious diseases. However, where should funding for important research come from? Who should pay for the expensive process of creating patient-specific stem cells and specialised cells for disease treatment?
Induced pluripotent stem cells (iPS cells) could potentially be used to create many cloned babies from an adult’s cells. What regulations should be put in place to control how iPS cell research is developed and applied? How can we legislate for future developments?
If research is tightly controlled by regulation and legislation, is there a risk that science becomes too much of a political issue? How much influence should non-specialist political lobbyists have?
Story cards
Policies
Stem cell research is only to be carried out on adult or cord blood stem cells.
As well as adult or cord blood stem cells, stem cell research can also be carried out using ‘surplus’ embryos under 14 days old that would be destroyed otherwise.
In addition to position 2, stem cell research can be carried out using embryos created specifically for research by IVF.
In addition to position 3, embryos can be cloned for stem cell research.
FUND is a project funded by the European Commission (