1: Stem Cells

Question 1

Define stem cells. What are their two key qualities?

Answer 1

1. cells that have the capacity to divide and differentiate along different pathways

• Self renewal: They can continuously divide and replicate
• Potency: They have the capacity to differentiate into specialised cell types

Question 2

What do human embryos entirely consist of in their early stages?

Answer 2

embryonic stem cells

Question 3

What happens to the stem cells in a human embryo as time goes on?

Answer 3

1. they gradually commit themselves to a pattern of differentiation

Question 4

Can a cell divide after it is committed?

Answer 4

1. yes, several more times

2. but all of the cells formed will differentiate the same way so they are no longer stem cells

Question 5

Are stem cells found in the adult body?

Answer 5

1. yes in small numbers

Question 6

Where are adult stem cells found?

Answer 6

1. most human tissues including: skin, liver and bone marrow

Question 7

To what extent can adult stem cells differentiate relative to embryonic stem cells?

Answer 7

1. they do not have as great a capacity as embryonic stem cells

Question 8

What do adult stem cells grant to tissues?

Answer 8

1. considerable powers of regeneration because stem cells means the possibility to make new cells

Question 9

Which tissues lack stem cells needed for effective repair?

Answer 9

1. brain, kidney, heart

Question 10

What might stem cells (probably embryonic) be used for?

Answer 10

1. tissue repair

2. degenerative conditions e.g. Parkinson’s disease

Question 11

What are ethics?

Answer 11

1. moral principles that allow us to decide whether something is morally right or wrong

Question 12

What should scientists always consider before doing research?

Answer 12

1. ethics of the research

2. the consequences of the research

Question 13

Give ethical argument in favour of use of stem cells.

Answer 13

1. health and quality of life of patients suffering from incurable conditions may be greatly improved

Question 14

What do ethical arguments against stem cell use depend on?

Answer 14

1. the source of the stem cells (embryonic/adult)

Question 15

How many objections are there to using adult stem cells? Explain.

Answer 15

1. pretty much none

2. because adults can give informed consent

Question 16

Can newborn babies give informed consent?

Answer 16

1. duh

Question 17

If babies cannot give informed consent, how can it be ethical for us to harvest stem cells from them?

Answer 17

1. their parents can give informed consent on their behalf

Question 18

Where are stem cells ‘harvested’ from in newborn babies?

Answer 18

1. their umbilical cord

Question 19

What are the stem cells harvested from babies usually used for?

Answer 19

1. stored in case they are needed during the babies subsequent life

Question 20

It seems that informed consent solves all ethical issues. Where might ethical issues involving stem cells be more controversial?

Answer 20

1. stem cells taken from specially created embryos are more controversial

Question 21

Why are stem cells taken from specially created embryos (more) controversial?

Answer 21

some argue:

1. embryo is a human life even at earliest stage
   - if the embryo dies as a result of the procedure, procedure is immoral
   - because a life has been ended the benefits from therapies using embryonic stem cells do NOT justify the taking of a life (nor the risk of taking a life)

Question 22

Consider the ‘embryo = human life’ argument against the use of embryonic stem cells. What are some counter-arguments (full version)?

Answer 22

1. early stage embryos are nothing more than a little ball of cells, yet to develop essential features of human. Therefore, they are not human
2. early stage embryos lack a nervous system so do not feel pain or suffer in other ways during stem cell procedures.
3. if embryo is produced deliberately, no individual that would otherwise have had the chance of living is denied the chance of life
4. large numbers of embryos produced by IVF are never implanted and do not get the chance of life; rather than kill these embryos it is better to use stem cells from them to treat disease and save lives

Question 23

Give two examples of diseases that can be treated with stem cells.

Answer 23

1. Stargadt’s muscular dystrophy (embryonic stem cells)

2. Leukemia (adult stem cells)

Question 24

What is Stargadt’s muscular dystrophy?

Answer 24

1. a genetic disease causing loss of vision

Question 25

Who does Stargadt's muscular dystrophy usually affect?

Answer 25

1. children | 2. develops in children between the ages of 6 and 12

Question 26

What are most cases of Stargadt's muscular dystrophy caused by?

Answer 26

1. a recessive mutation of a gene called ABCA4

Question 27

What does the recessive mutation of the gene ABCA4 cause?

Answer 27

1. causes a membrane protein used for active transport in retina cells to malfunction 2. this means that photoreceptive cells degenerate and vision becomes progressively worse 3. the loss of vision can be severe enough for the person to be registered as blind

Question 28

How is Stargadt's muscular dystrophy being treated using stem cells?

Answer 28

researchers have developed methods for making.... 1. embryonic stem cells develop into retina cells (remember that embryonic stem cells can differentiate along any pathway)

Question 29

How did scientists first test their cure for Stargadt's muscular dystrophy?

Answer 29

1. first experimented on mouse cells

Question 30

In 2010, a woman in her 50s with Stargadt's disease was treated. How? What was the conclusion of the research?

Answer 30

1. 50,000 retina cells derived fro embryonic stem cells were injected into her eyes 2. the cells attached to the retina and remained their during the 4 month trial period 3. there was an improvement in her vision and no harmful side effects 4. further research needed but we can be optimistic about future treatment of Stargadt's with embryonic stem cells

Question 31

What sort of disease is leukemia? What happens when a person has leukemia?

Answer 31

1. cancer | 2. abnormally large numbers of white blood cells are produced in the bone marrow

Question 32

What is a normal white blood cell count?

Answer 32

1. 4,000 - 11,000 white blood cells / mm³

Question 33

What can the white blood cell count rise to in someone with leukemia?

Answer 33

1. leukemia: above 30,000 white blood cells / mm³ | 2. acute leukemia: over 100,000 white blood cells / mm³

Question 34

How is leukemia treated?

Answer 34

1. adult stem cells used 2. large needle inserted into a large bone, usually the pelvis and fluid is removed from the bone marrow 3. stem cells are extracted from this fluid and are stored by freezing them. They are adult stem cells so only have potential to produce blood cells 4. high dose of chemotherapy drugs to kill all cancer cells in bone marrow. Bone marrow loses its ability to produce blood cells. 5. Stem cell then returned to patient's body. The cells re-establish themselves in the bone marrow, multiply and start to produce red and white blood cells. 6. In many cases this procedure cures leukemia completely.