Lecture 27: Stem cells

Question 1

What are stem cells?

Answer 1

• Unspecialised cells capable of renewal by cell division.

- Can be induced to become tissue specific mature cells with special functions

Question 2

What are the different types of potency?

Answer 2

Totipotent -> Embryonic tissues
Pluripotent - Any cell (Embryonic stem cells)
Multipotent (i.e heamopoetic stem cells) and unipotent-single lineage i.e skin (adult stem cells)

Question 3

What are some examples of multipotent stem cells?

Answer 3

Mesenchymal stem cells i.e found in bone marrow.
Can turn into; Adipocytes, cartilage, bone, tendons, muscle and skin
Release; Anti-inflam and immomudulatory factors

Question 4

Do all organs have stem cells?

Answer 4

No ie kidneys do not, nor heart

Found in

• Brain
• Blood
• Muscle
• Gut
• Skin

Question 5

What are some examples of adult stem cell therapies?

Answer 5

Blood stem cell transplants
Skin grafts (have stem cells)
Corneal transplants (have stem cells)

Question 6

What are pluripotent stem cells?

Answer 6

Self renewing cells that are capable of differentiating into any tissue

Question 7

What are some examples of pluripotent stem cells?

Answer 7

Embryonic stem cells

Induced pluripotent stem cells (iPSCs)

Question 8

In an embryo where are the pluripotent cells found?

Answer 8

In the inner cell mass of the blastocyst prior to gastrulation (formation of three germ layers that each give rise to a limited number of tissue types, reduced potency)

Question 9

How was the potency of ICM cells tested?

Answer 9

ICM cells were taken from the embryo of a black mouse and injected into the blastocyst of a brown mouse. The embryo was then placed back in a black mouse and the baby was chimera.

Question 10

What are some notes on ES cells?

Answer 10

• Can be maintained indefinitely in cell culture

- Cant perform blastocyst injections with hES cells.

Question 11

Why does the blastocyst in which ICM cells are injected into accept the ICM cells?

Answer 11

The blastocyst host cells are tetraploid and contribute only to the placental tissues

The injected ICM / ES give rise to the embryo

Question 12

What is a teratoma assay?

Answer 12

Injecting Stem cells into any tissue i.e not embryonic and watching the formation of a teratoma over time consisting of the different formed germ line cells

Question 13

What is an embryoid body assay? // not sure what the learning point of…

Answer 13

Cultured ES cells are exposed to differentiation media and three germ tissues can be detected i.e

Question 14

What is the potential of ES cells?

Answer 14

• Tissue engineering
• Cell based therapies
• Disease in a dish models

Question 15

What is the challenge to overcome with ES cells?

Answer 15

• Teratoma
• Purity of cells
• Ethical concerns
• Immunologically privileged sites = brain and spinal cord, eye, testes i.e rejection is a concern

Question 16

What is cloning?

Answer 16

Somatic cell nuclear transfer

i.e put DNA in a terminally differentiated nucleus, can form ES cells also babies….

Question 17

Describe induced pluripotent stem cells;

Answer 17

Somatic cell nucleus is obtained and placed in an enucleated egg or oocyte. It is then exposed to reprogramming factors and reprogrammed to embryonic state. = iPSC

Question 18

What are the reprogramming factors for creating iPCS?

Answer 18

Oct4
SOX2
Klf4
cMYC

Question 19

What are the benefits of iPSC?

Answer 19

• No immune rejection if cells are reprogrammed from patient
• No moral objections b/c no embryo
• BUT teratoma risk remains, purity…

Question 20

What method can be used for gene editing of iPS cells?

Answer 20

CRISPR = efficient and fast

i.e sickle cell anemia…

Question 21

What is another use of iPS cells?

Answer 21

Using IPS cells to grow human organs in animals

or

developing organoids i.e disease in a dish