4.10 Stem Cells in Medicine

Question 1

What are the two types of stem cells in humans?

Answer 1

• Embryonic stem cells which are found in the early embryo (can differentiate into any type of specialised cell).
• Adult stem cells which are found in the bone marrow of all ages (can only differentiate into different types of blood cells).

Question 2

Describe diabetes, paralysis and sickle cell anaemia are due to faulty cells (3)

Answer 2

• Type 1 diabetes: damage to the pancreas cells that normally produce insulin.
• Paralysis: sometimes caused by damaged nerve cells.
• Sickle cell anaemia: caused by misshapen red blood cells.

Question 3

How may scientists use embryonic stem cells to help people with certain conditions due to faulty cells? (4)

Answer 3

1. Extract embryonic stem cells from early embryos.
2. Grow them in a laboratory.
3. Stimulate them to differentiate into whichever type of specialised cell that we want.
4. Then give them to the patient to replace their faulty cells.

Question 4

Drawbacks of using embryonic stem cells in medicine (2)

Answer 4

1. Requires embryonic stem cells - they are the only ones which can differentiate into any type of cell however they need to be extracted from embryos which are limited. Also, there are ethical issues associated with it.
2. Rejection - As the embryo and the patient have different genomes, the patient’s immune system may reject the stem cells, which means it tries to destroy them because it identifies them as foreign. We can reduce the risk of this by giving the patient medication to suppress their immune system but this doesn’t always work and often has side effects.

Question 5

Why are adult stem cells an alternative to using embryonic stem cells in medicine?

Answer 5

They are easier to get hold of and won’t cause rejection as they can be taken from the patient themself.

Question 6

What are the downsides of using adult stem cells in medicine? (2)

Answer 6

• They can only differentiate into different types of blood cells. So while we could use them to treat blood disorders like sickle cell anaemia, we couldn’t use them to treat other conditions like diabetes or paralysis.
• However, there is some new research exploring how we could use adult stem cells to produce any type of cell.
• Adult stem cells are taken from the patient so are not in limited supply.

Question 7

Risks of using stem cells in medicine (2)

Answer 7

1. Tumour development - stem cells divide very quickly. If scientists are unable to control the rate at which the transplanted cells divide inside a patient, a tumour may develop.
2. Disease transmission - viruses live inside cells. If donor stem cells are infected with a virus and this isn’t picked up, the virus could be passed on to the recipient and so make them sicker.

Question 8

Ethical debate to using embryonic stem cells in medicine

Answer 8

• Some people argue that human embryos shouldn’t be used to provide stem cells because the embryo gets destroyed and each one is a potential human life.
• But others think that the aim of curing patients who are suffering should be more important than the potential life of the embryos.
• Also, the embryonic stem cells that are used are normally unwanted ones from fertility clinics.

Question 9

When nerve cells are damaged, messages can no longer be sent to the muscles properly. This can lead to the loss of the ability to move some or all of your body. What do we call this condition?

Answer 9

Paralysis