Stem Cells

Question 1

What types of stem cells are there?

Answer 1

Embryonic stem cells, which divide and differentiate into each of the types of cells in the adult body.
Induced pluripotential stem cells (IPS).
Adult stem cells, which divide and differentiate into lineage restricted cell types.

Question 2

What is the zygote?

Answer 2

A totipotent stem cell

Question 3

What is differential gene expression?

Answer 3

The reversible epigenetic changes that are gradually imposed ok the genome during development.

Question 4

Define:
Totipotent?
Pluripotent? 
Multipotent?
Oligopotent?
Unipotent?

Answer 4

Totipotent: sufficient to form entire organism
Pluripotent: able to form all of the body’s cell lineages
Multipotent: can form multiple cell lineages that can contribute to an entire tissue or tissues
Ologopotent: able to form two or more lineages within a tissue
Unipotent: forms a single lineage

Question 5

Define embryonic stem cells?

Answer 5

Pluripotent cells that can self renew in culture.

Question 6

How is pluripotent of embryonic stem cells maintained?

Answer 6

The transcription factors OCT4, SOX2, NANOG and KLF4 suppress the expression of genes required for differentiation.

Question 7

How do you test for pluripotency?

Answer 7

Allow cells to differentiate spontaneously by clumping forming embryoid bodies, manipulate cells so that they will differentiate into three germ layers and inject an immunosuppressed mouse to test for teratoma formation.

Question 8

Describe the steps of differentiation?

Answer 8

Embryoid body at 8 days then single complex human embryoid at 14 days. Neural cells and pigmented epithelial cells followed by colony erythyroid progenitors and colony granulocyte-macrophage progenitors.

Question 9

What do induced pluripotent stem cells do?

Answer 9

Produce pluripotent stem cells without embryos.

Question 10

How do you program somatic cells to be pluripotent?

Answer 10

Isolate a somatic cell and isolate the dermal fibroblasts, culture them in a lab and reprogram them with the pluripotential genes using a vector and required growth factors to induce a pluripotent state.

Question 11

What are a) haematopoietic stem cells, b) mesenchymal stem cells and c) neuronal stem cells?

Answer 11

a) multipotent stem cells that give rise to the cells of the blood
b) multipotent stem cells that give rise to the cells of bone, cartilage, fat, fibrous connective tissue and cells that support blood formation
c) oligopotent stem cells that give rise to the brains three major cell types: astrocytes, oligodendrocytes and neurons.

Question 12

Where are adult stem cells found?

Answer 12

In many organs and tissues: blood, blood vessels, skeletal muscles, skin, teeth, gut, liver and heart.

Question 13

What is a stem cell niche?

Answer 13

An area where adult stem cells are thought to reside which regulate how the stem cells are involved in tissue repair, regeneration and maintenance.

Question 14

What can stem cell niches be regulated by?

Answer 14

Paracrine, neuronal, physical, metabolic and humoral factors.

Question 15

What may adult stem cells do?

Answer 15

They may remain quiescent until activated and needed tot produce more cells to maintain tissue by disease of injury.

Question 16

What are haematopoeitc stem cell therapies also called?

Answer 16

Bone marrow transplant.

Question 17

What are bone marrow transplants used to treat?

Answer 17

Diseases of in born error and acquired diseases.

Question 18

What are the two types of bone marrow transplants?

Answer 18

Autologous, which does not require immunosuppressive therapy as the patients own cells are used.
Apologenic: requires immunosuppressive therapy as the stem cells are from other patients.

Question 19

What are complications with bone marrow transplants?

Answer 19

Donors are required, require an intact bone marrow niches, stem cell competition can be a problem, infection risk etc.

Question 20

What is the potential of bone marrow transplants?

Answer 20

Regeneration of diseases tissues; including bones, cartilage, ligaments and tendons, tissue engineering and immunomodulation.

Question 21

What are the clinical potentials of embryonic and induced pluripotent stem cells?

Answer 21

Used for treatment of diseases in tissues on non-mesenchymal origin and application requiring a large number of cells as these cannot be obtained through mesenchymal stem cells.

Question 22

What are possible problems with stem cell treatments?

Answer 22

Ethical issues, safety issues.

Question 23

Define a stem cell?

Answer 23

A cell that can continuously divide through mitosis to produce unaltered daughter cells and also have the ability to divide into differentiated cells and produce daughter cells that have different, more restrictive properties.