Stem Cells (AQA GCSE Combined Science: Synergy: Life & Environmental Sciences): Revision Note
Exam code: 8465
Sources of stem cells
Stem cells used in medical research can come from different sources and vary in their ability to differentiate into specialised cells
These differences affect how useful each type of stem cell is for research and potential treatments
The table below summarises the main types of human stem cells used in research, their sources, and what they can develop into
Stem cell type | Source | Potential of cell | What can be produced from them |
|---|---|---|---|
Embryonic stem cells | Inner cell mass of an embryo a few days old | Undifferentiated / unspecialised | All different types of specialised cells found in the body |
Adult stem cells | Bone marrow | Limited ability to differentiate / partially specialised | Mainly blood cells including red blood cells, white blood cells and immune system cells |
Skin | Limited ability to differentiate / partially specialised | Cells found in the different layers of the skin and hair follicles | |
Other organs such as the liver and brain | Limited ability to differentiate / partially specialised | Cells found in these specific organs | |
Fetal (umbilical cord) stem cells | Blood from the umbilical cord | Limited ability to differentiate / partially specialised | Blood cells, including red and white blood cells, and some muscle and nerve cells |
Stem Cells in Medicine
Current uses of stem cells
One well-established medical use of stem cells is bone marrow transplants
Bone marrow contains adult stem cells
These stem cells can divide and differentiate into different types of blood cells
In leukaemia, the bone marrow produces abnormal white blood cells
A bone marrow transplant replaces the patient’s damaged bone marrow
The transplanted stem cells produce healthy new blood cells
This helps restore normal blood and immune system function
Future uses of stem cells
However, most medical uses of stem cells are still in the experimental stage
Researchers are investigating how stem cells could be used to treat a range of diseases by replacing damaged or non-functioning cells
Disease | Problem | How stem cells could be used to treat | Source of stem cells |
|---|---|---|---|
Diabetes (Type 1) | Inability of the pancreas to produce insulin to control blood sugar levels | Stem cells could be differentiated into insulin-producing pancreatic cells which are transplanted into the patient’s body | Stem cell donors or embryonic stem cells |
Paralysis | Damage to nerve cells in the brain or spinal cord, preventing signals from the brain reaching muscles in parts of the body such as the arms or legs resulting in loss of movement | Stem cells could be differentiated into nerve cells which are transplanted into the damaged region of the nervous system | Stem cell donors or embryonic stem cells |
Heart disease | Damage to heart muscle caused by a heart attack reduces the heart’s ability to pump blood effectively | The patient’s own stem cells from bone marrow can be differentiated into heart muscle cells and injected into damaged areas of the heart to repair tissue | Patient’s own bone marrow stem cells |
Risks of stem cell use
The properties of stem cells are not yet fully understood
Scientists do not fully understand how stem cell differentiation is controlled
Stem cells have a high ability to divide and proliferate
If differentiation is not properly controlled, cells may continue dividing
Uncontrolled cell division can lead to tumour formation
There is a risk that transplanted stem cells could cause cancer
This risk is a major concern when using stem cells in medical treatments
Evaluating Stem Cells in Medicine
Benefits of using stem cells | Risks / issues of using stem cells | Social issues | Ethical issues |
|---|---|---|---|
Great potential to treat a wide variety of diseases, from diabetes to paralysis | Stem cells cultured in the lab could become infected with a virus which could be transmitted to the patient | It is possible for embryonic stem cells to be collected before birth from amniotic fluid or after birth from umbilical cord blood and stored by a clinic, but this can be expensive and is not an option for everyone | Stem cells may be sourced from unused embryos produced in IVF treatment, raising questions about who has the right to use them |
Organs developed from a patient’s own stem cells reduces the risk of organ rejection and removes the need to wait for an organ donation | There is a risk of cultured stem cells accumulating mutations that can lead to cancer cells developing | A lack of peer-reviewed clinical evidence of the success of stem cell treatments | Is it right to create embryos through therapeutic cloning and then destroy them, and who owns the embryo |
Adult stem cells are already used successfully in treatments, acting as proof of benefits | Low numbers of stem cell donors | Educating the public sufficiently about what stem cells can and cannot be used for | Should an embryo be treated as a person with human rights or as a commodity |
Examiner Tips and Tricks
When you are asked to evaluate the use of stem cells, don’t just list facts. You need to weigh up both sides. Include at least one benefit (such as treating disease or reducing organ rejection) and one risk or ethical concern (such as cancer risk or the use of embryos).
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