Stem Cells

Question 1

Define stem cell

Answer 1

An undifferentiated cell able to give rise to various differentiated cells.

Question 2

What are 2 important and distinguishing properties of stem cells?

Answer 2

1. Self-renewal capacity

2. Asymmetric division

Question 3

What is asymmetric division?

Answer 3

One daughter cell differentiates and gives rise to mature cells, while the other daughter cell remains undifferentiated and retains its capacity for self-renewal

Question 4

What are the differences between embryonic and adult stem cells?

Answer 4

1. Embryonic stem cells are totipotent - can create all the different cells of the body - while adult stem cells can usually only create the cells of the specific tissue to which it belongs
2. Embryonic stem cells are found in the inner cell mass of the blastocyst of a developing embryo and nowhere else, adult stem cells are found throughout the body in stem cell niches

Question 5

What is an iPS?

Answer 5

An induced pluripotent stem cell. A handful of genes have been found, the products of which can cause fully differentiated somatic cells to achieve stemness. iPS are created by introducing these genes into adult tissue cells.

Question 6

What is the purpose of iPS?

Answer 6

To overcome the immunogenicity of embryonic stem cells.

Question 7

Where are liver stem cells found?

Answer 7

Canals of Hering

Question 8

Where are skin stem cells found?

Answer 8

1. Lower layer epidermis
2. Bulge area of hair follicle
3. Sebaceous glands

Question 9

Where are intestinal stem cells found?

Answer 9

Near base of crypt, above Paneth cells

Question 10

Where are neural stem cells found?

Answer 10

Subventricular zone and dentate gyrus

Question 11

Where are corneal stem cells found?

Answer 11

Limbus

Question 12

Where are connective tissue and muscle stem cells (mesenchymal stem cells) found?

Answer 12

Bone marrow

Question 13

Where are haematopoietic stem cells found?

Answer 13

Bone marrow

Question 14

What is Oct4?

Answer 14

The gatekeeper of embryonic stem cell pluripotency. A transcription factor that is absolutely required for embryonic stem cells to remain pluripotent.

Question 15

What is NANOG?

Answer 15

Another transcription factor that in concert with Oct4 maintains the pluripotency and self-renewal capacity of embryonic stem cells.

Question 16

What is the role of Oct4 and NANOG in tumorigenesis?

Answer 16

Overexpression of these transcription factors, either together or separately are associated with tumorigenesis, metastasis and even distant recurrence in different types of cancer including prostate and breast cancer. May contribute to the de-differentiation of tumour cells and are found at high levels in poorly differentiated cancers.