Stem Cells and Regenerative Medicine

Question 1

Define ‘stem cells’

Answer 1

These are primitive, undifferentiated cells which can divide indefinitely and are self-renewing, giving rising to progeny that then differentiate into specialised cells.

Question 2

What are pluripotent stem cells?

Answer 2

Can differentiate into cells derived from any of the three germ layers

Question 3

What are multipotent stem cells?

Answer 3

can give rise to several specialised cells or tissues of an organism (often tissue-specific) e.g. Haemopoeitic stem cells

Question 4

What are oligopotent stem cells?

Answer 4

Can generate a few cell types within a particular tissue

Question 5

What are unipotent stem cells?

Answer 5

Can produce only one cell type, but still capable of self-renewing

Question 6

What are adult stem cells?

Answer 6

Rare, undifferentiated cells found among differentiated cells in a tissue or organ. They are capable of differentiating to produce the major specialised cell types of the tissue; adult stem cells are multipotent.

Question 7

What is the primary role of adult stem cells?

Answer 7

To maintain and repair the tissue in which they are found.

Question 8

How could you identify an embryonic stem cell in a culture?

Answer 8

Grow indefinitely in culture in the primitive embryonic state, maintain normal karyotype and expression of telomerase (immortal cell division). presence of markers that are only found in undifferentiated cells, able to differentiate into a wide range of cell types in vitro and in vivo

Question 9

What are the 3 germ cell layers?

Answer 9

Endoderm, mesoderm and ectoderm

Question 10

What is endoderm?

Answer 10

The internal layer of germ cells which gives rise to pancreas, liver, thyroid, lung, bladder and urethra

Question 11

What is mesoderm?

Answer 11

The middle layer of germ cells which gives rise to bone marrow, skeletal/smooth/cardiac muscle, heart, blood vessels and kidney tubules

Question 12

What is ectoderm?

Answer 12

The external layer of germ cells which gives rise to skin, neurones, eyes, ears and pituitary gland

Question 13

What are stem cell niches?

Answer 13

Stem cells though to be maintained and perhaps defined by the environment produced by surrounding differentiated cells; differentiated cells may secrete specific factors into surrounding matrix or communicate with stem cells via gap junctions - can induce a stem cell to die, divide or differentiate

Question 14

Describe symmetric stem cell division

Answer 14

2 stem cells or two differentiated cells produced

Question 15

Describe asymmetric stem cell division

Answer 15

Stem cell and differentiated cell produced

Question 16

Why is therapeutic cloning beneficial?

Answer 16

Ideal tissue for regenerative medicine because it is genetically identical to patient (circumvents problem of tissue rejection), use to study diseases

Question 17

What are the challenges of therapeutic cloning?

Answer 17

Percentage of successful clones is low, creating potential embryo (not fertilised) for research or treatment, practical source of oocytes, slippery slope to reproductive cloning

Question 18

What are some of the challenges with the use of embryonic stem cells for transplantation therapies?

Answer 18

Purity and production problems, cancer problems (embryonic stem cells may give rise to disorganised growths known as teratomas), immunology problems, have to be able to match the graft to the donor, ethical issues

Question 19

What are the advantages of using adult stem cells over embryonic cells

Answer 19

No legal/ethical concerns, using own cells circumvents issues with immunological rejection, shown no lead to tumour formation

Question 20

What are the advantages of using iPS cells

Answer 20

No need for embryos, and circumvents immunological rejection

Question 21

What are the challenges of using iPS cells

Answer 21

High risk of cancer, requires treatment for viral integration, haven’t been able to demonstrate the long-term stability of the reprogrammed cells, and would have to improve the technical efficiency