L3 - Adult Stem Cells

Question 1

Stem cells undergo mitotic division to produce?

Answer 1

Two daughter cells

• Stem cell - endless self-renewal
• Specialised cell - differentiation to multiple lineages/fates

Question 2

What are the characteristics of a progenitor cell?

Answer 2

Shows limited self-renewal – copying

Shows limited differentiation – specialising

Question 3

What is the role of self-renewing?

Answer 3

Maintains the stem cell pool

Question 4

What is the role of differentiation?

Answer 4

Replaces dead or damaged cells throughout your life
Adds new cells through life to increase organ size
Generates cell types specifically required at a certain time in life

Question 5

Where are embryonic stem cells found?

Answer 5

Blastocyst

Question 6

Where are tissue/adult stem cells found?

Answer 6

Foetus
Baby
Throughout life

Question 7

What are the two different layers of the blastocyst?

Answer 7

Cells on inside – form the embryo

Cells on outside – form the trophectoderm

Question 8

Where are embryonic stem cells derived from?

Answer 8

Refers to stem cells taken from the blastocyst inner cell mass
They are then cultured in the lab, in a fluid filled with nutrients, to grow more cells

Question 9

What are the characteristics of embryonic stem cells?

Answer 9

They are pluripotent – can form all possible types of specialised cells when exposed to different differentiation factors

Question 10

What are the characteristics of adult stem cells?

Answer 10

As development proceeds, most somatic cells are differentiated and not mitotic
However there are adult stem cells or tissue-specific stem cells
These are multipotent

Question 11

Where were adult stem cells first recognised?

Answer 11

Bone marrow
Liver
Gut
Skin

Question 12

Where are adult stem cells not recognised?

Answer 12

Brain

Muscle

Question 13

What is the role of adult stem cells?

Answer 13

Self-renew and differentiate to become most or all the specialized cell types within their specific tissue lineage
Maintain cell populations
Help you heal
Play a role in ageing

Question 14

What is cellular homeostasis?

Answer 14

It is the constant or periodic generation of new cells to replace old, damaged, and dying cells, or the addition of new cells as needed

Question 15

What is the role of adult stem cells in cellular homeostasis?

Answer 15

Adult stem cells fulfil this role through regeneration

This regeneration mirrors the way the cells form in the embryo

Question 16

What are the 5 types of adult stem cells?

Answer 16

Hematopoietic stem cells - blood and immune system
Mesenchymal stem cells - bone, cartilage, fat, muscle, tendon/ligament
Epithelial stem cells - skin, gut, other linings
Muscle stem cells
Neural stem cells - neurons, glial cells, retinal cells

Question 17

What are stem cell niches?

Answer 17

All adult stem cells reside is specialised niches
Complex microenvironment made up of many cells (stromal support cells) that interact with the environment and the stem cell to decide whether to activate it
Involves a feedback mechanism from progenitors to niche
All niches have a specialised portal blood vessel to allow communication
Ensures you get correct amount of self-renewal
Within the niche can have stem cells in a quiescent state

Question 18

What do hematopoietic stem cells give rise to?

Answer 18

Give rise to all blood cell types

• Myeloid –macrophages, neutrophils, eosinophils, erythrocytes, platelets, dendritic cells
• Lymphoid – T-cells, B-cells, NK-cells

Question 19

Where are hematopoietic stem cells found?

Answer 19

Found in the bone marrow, umbilical cord blood and placental tissue

Question 20

What is the role of stromal support cells?

Answer 20

Some of the factors (SCF) released by stromal support cells (that support hematopoietic cells) are the same as those secreted to keep primordial germ cells undifferentiated

Question 21

What cells cause the regeneration of skeletal muscle?

Answer 21

Satellite cells

Question 22

Where are satellite cells found?

Answer 22

Normally quiescent

Located outside the muscle fibre, under the basal lamina

Question 23

How do satellite cells function?

Answer 23

Tissue homeostasis and long-term regenerative capability of satellite cells involves coordination between myogenesis and self-renewal

Question 24

What projects investigate mechanisms controlling long-term self-renewal in skeletal muscles?

Answer 24

Use different markers to mark either the self-renewing cell or the differentiating myogenic cell
Role of diet, primary cilia and cell signalling in asymmetric cell division and self-renewal

Question 25

What do mesenchymal stem cells differentiate into?

Answer 25

Cartilage cells - chondrocytes
Muscle cells – myocytes
Fat cells – adipocytes
Tendons, ligaments and connective tissue

Question 26

Where are mesenchymal stem cells found?

Answer 26

Bone marrow, fat and cord blood

Question 27

What do epithelial stem cells differentiate into?

Answer 27

Give rise to epithelial cells which constitute 60% of the differentiated cells in the body

Question 28

What are epithelial stem cells responsible for?

Answer 28

Responsible for covering internal and external surface
E.g. gut and skin
- Both need constant replacement

Question 29

Where are neural stem cells found?

Answer 29

Subventricular zone lining lateral ventricles
- Give rise to newly born neurones that migrate to olfactory bulb
Subgranular zone of dentate gyrus of hippocampus
- Involved in new memory acquisition
Hypothalamus lining 3rd ventricle
- Contribute new neurones to energy/feeding circuits