Stem Cells

Question 1

What is a stem cell?

Answer 1

A cell that can either self-renew or give rise to more specialized cell types.

Question 2

Characteristics of stem cells (5)

Answer 2

1. Not terminally differentiated.
2. Can divide without limit.
3. Undergo slow division.
4. When it divides, it gives rise 1 cell with stem characteristics and 1 with the ability to be differentiated.
5. Adult stem cells are tissue specific.

Question 3

Totipotency

Answer 3

Ability to give rise to all cells of an organism, including embryonic and extraembryonic tissues (placenta). Located in the zygote.

Question 4

Pluripotency

Answer 4

Give rise to cells that make up the body (embyronic cells). Located in the blastocyst.

Question 5

Multipotency

Answer 5

Give rise to different cell types of a given lineage (ex: cord blood cells can give rise to RBC, moncyte, and leukocyte). An adult stem cell. Located in various tissues.

Question 6

Founder stem cells (3)

Answer 6

Programmed to have a fixed number of divisions.
Controlled by a short range signals.
Define the size of large final structures.

Question 7

Transit amplifying cells (4)

Answer 7

Divide frequently.
Transit from a stem cell to a differentiated cell.
Programmed to have limited number of divisions.
Committed.

Question 8

Divisional asymmetry

Answer 8

Asymmetric division of cells, resulting in 1 with stem cell characteristics and 1 with factors that give it the ability to differentiate.

Question 9

Environmental asymmetry

Answer 9

Division makes 2 identical cells but the environment may influence/alter 1 cell.

Question 10

Immortal strand hypothesis

Answer 10

Daughter cells retain stem cell status and capability for long term renewal by selectively retaining original DNA.

Question 11

Embryonic stem cells (6)

Answer 11

Derived from blastocyst.
Can proliferate indefinitely.
Unrestricted developmental potential.
Can re-integrate when re-introduced to to blastocyst.
Develop into different cell types.
Can become a tumor.

Question 12

Teratoma

Answer 12

Germ cell mass containing cells from different sources (ex: hair, muscle, bone).

Question 13

Transcription factors responsible for maintenance of pluripotent stem cells in embryo (4 FONS)

Answer 13

FoxD3
Oct4
Nanog
Sox2

Question 14

Growth factors found in pluripotent cells (2 CG)

Answer 14

Cripto

GDF-3

Question 15

Problem with the application of adult stem cells

Answer 15

Harvested cells have memory of their original cell type; they cannot be coerced to become a cell of a different tissue. Experts believe adult stem cells cannot replace embryonic stem cells.

Question 16

Hematopoietic stem cells (HSCs)

Answer 16

Differentiated as blood components.

Question 17

Mesenchymal stem cells (MSCs)

Answer 17

Differentiated as connective tissues and organ tissue.

Question 18

Cord blood

Answer 18

Undifferentiated and does not require gene manipulation.

Question 19

Immune rejection

Answer 19

If adult stem cells are not genetically the same, the grafted cells can be rejected by the host. The host develops an immune reaction.

Question 20

Somatic cell nuclear transfer (SCNT)

Answer 20

Nucleus from somatic cell injected into oocyte of a donor, replacing the oocyte nucleus. Blastocyst from hybrid oocyte generated and ES cells isolated. Solves rejection ass because the cells will express the patient’s genes.

Question 21

iPS cells (induced pluripotent stem cells)

Answer 21

Recombinant DNA technologies used to develop pluripotent stem cells starting differentiated adult cells.

Question 22

Challenges of SCNT (2)

Answer 22

1. Inefficient - may take hundreds of oocyes.

2. Technically demanding - needs to be available in many hospitals.