L3 - Adult Stem Cells Flashcards
Stem cells undergo mitotic division to produce?
Two daughter cells
- Stem cell - endless self-renewal
- Specialised cell - differentiation to multiple lineages/fates
What are the characteristics of a progenitor cell?
Shows limited self-renewal – copying
Shows limited differentiation – specialising
What is the role of self-renewing?
Maintains the stem cell pool
What is the role of differentiation?
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
Where are embryonic stem cells found?
Blastocyst
Where are tissue/adult stem cells found?
Foetus
Baby
Throughout life
What are the two different layers of the blastocyst?
Cells on inside – form the embryo
Cells on outside – form the trophectoderm
Where are embryonic stem cells derived from?
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
What are the characteristics of embryonic stem cells?
They are pluripotent – can form all possible types of specialised cells when exposed to different differentiation factors
What are the characteristics of adult stem cells?
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
Where were adult stem cells first recognised?
Bone marrow
Liver
Gut
Skin
Where are adult stem cells not recognised?
Brain
Muscle
What is the role of adult stem cells?
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
What is cellular homeostasis?
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
What is the role of adult stem cells in cellular homeostasis?
Adult stem cells fulfil this role through regeneration
This regeneration mirrors the way the cells form in the embryo
What are the 5 types of adult stem cells?
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
What are stem cell niches?
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
What do hematopoietic stem cells give rise to?
Give rise to all blood cell types
- Myeloid –macrophages, neutrophils, eosinophils, erythrocytes, platelets, dendritic cells
- Lymphoid – T-cells, B-cells, NK-cells
Where are hematopoietic stem cells found?
Found in the bone marrow, umbilical cord blood and placental tissue
What is the role of stromal support cells?
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
What cells cause the regeneration of skeletal muscle?
Satellite cells
Where are satellite cells found?
Normally quiescent
Located outside the muscle fibre, under the basal lamina
How do satellite cells function?
Tissue homeostasis and long-term regenerative capability of satellite cells involves coordination between myogenesis and self-renewal
What projects investigate mechanisms controlling long-term self-renewal in skeletal muscles?
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
What do mesenchymal stem cells differentiate into?
Cartilage cells - chondrocytes
Muscle cells – myocytes
Fat cells – adipocytes
Tendons, ligaments and connective tissue
Where are mesenchymal stem cells found?
Bone marrow, fat and cord blood
What do epithelial stem cells differentiate into?
Give rise to epithelial cells which constitute 60% of the differentiated cells in the body
What are epithelial stem cells responsible for?
Responsible for covering internal and external surface
E.g. gut and skin
- Both need constant replacement
Where are neural stem cells found?
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
