GCSE Biology - AQA
4.1.5 - Medical Uses of Human Stem Cells
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Because stem cells can differentiate into specialised cells, they have the potential to be used in medicine to replace cells in damaged or diseased tissues.
Stem cells are already used in this way in bone marrow transplants. Bone marrow transplants are used to treat blood cancers (such as leukemia and lymphoma) as well as some other conditions. In a bone marrow transplant, healthy adult stem cells from the bone marrow (often from another person) are used to replace damaged ones.
In a bone marrow transplant, healthy bone marrow stem cells are injected into the patient's bones to replace damaged ones.
Many researchers are trying to develop stem cell treatments for other medical conditions. Most of this research is focused on using embryonic stem cells, since they can differentiate into a much wider range of cell types than adult stem cells.
At an early stage in the development of a human, the embryo becomes a ball of cells. Within this ball of cells, at one end, there is a clump of embryonic stem cells. Scientists have learnt how to extract these cells from a human embryo and keep them alive. The rest of the embryo is destroyed in the process.
Embryonic stem cells can be extracted from a human embryo. The embryo is destroyed in the process.
In order to obtain embryonic stem cells for use in research or medicine, you need a human embryo to extract them from. There are two main ways to get human embryos for this purpose.
The first way is to use leftover embryos from a fertility treatment called IVF. In IVF, egg cells and sperm cells are combined outside of the body in a laboratory in order to produce several zygotes, each of which develops into a embryo. One of these embryos is implanted into the uterus of a person who wants to get pregnant. If the process is successful, this embryo will develop into a fetus and then be born. The rest of the embryos are unneeded. These embryos are sometimes used as a source of embryonic stem cells. If they were not used in this way, they would still be destroyed.
IVF is a fertility treatment used to help people get pregnant. It produces leftover embryos, which are sometimes used as a source of stem cells.
The second way is through a process called therapeutic cloning. In therapeutic cloning, an embryo is created using DNA from a patient. Embryonic stem cells can then be extracted from this embryo. These embryonic stem cells could then potentially be used to treat the patient. The advantage of using therapeutic cloning is that the stem cells that are produced are genetically identical to the patient's cells, so the patient's body will not reject them.
In therapeutic cloning, an embryo is created which is genetically identical to the patient. Embryonic stem cells are then extracted from this embryo. One day, it might be possible to use these stem cells to treat medical conditions.
Once human embryonic stem cells have been obtained, they can be cloned to produce more of them, and they can be made to differentiate into almost any human cell type.
It is hoped that these cells could one day be used to treat a wide range of medical conditions, including diabetes and paralysis.
A patient with diabetes talking to a community health worker about their condition. It is hoped that one day it will be possible to use embryonic stem cells to treat diabetes, along with many other conditions.
Although there are many promising areas of research, so far there are no widely used medical treatments that use embryonic stem cells. Bone marrow transplants are the only widely used form of stem cell treatment and they use adult stem cells, not embryonic stem cells.
There are problems with using human stem cells.
One problem is the risk of viral transfer. When stem cells from one person (a donor) are put into the body of another person (a patient), there is a risk that the donor could be infected with viruses, and these viruses could be transferred to the patient's body.
Another issue is that some people have ethical or religious objections to the use of human stem cells.
This is especially the case for embryonic stem cells since human embryos have to be destroyed to obtain them.
Also, in therapeutic cloning, the embryos which are produced are clones of an existing person. Of course, the embryos are destroyed and not allowed to develop further. However, some people may worry that such an embryo could one day be allowed to develop to maturity, in which case it would become a person who is a clone of an existing person. Also, some people may object to the production of embryos which are clones even if they are destroyed.
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How can human embryonic stem cells be obtained for research and medical treatment?
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What is the advantage of using therapeutic cloning rather than using embryos from IVF?
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What can be done with human embryonic stem cells once they have been obtained?
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How might human embryonic stem cells be used in the future?
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What are some of the problems with using human stem cells?
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