L6 The stem cell niche Flashcards
Where are adult stem cells generally found in?
They are found in special micro environments called niches.
What type of cells does the embryo start off as?
A clump of totipotent stem cells (embryonic stem cells).
What are the different distinct stem cells in the adult?
- Mesenchymal stem cells: Bone cells (osteoblasts), cartilage cells (chondrocytes) and fat cells (adipocytes)
- Blood stem cells: red blood cells, platelets and white blood cells
- Satellite stem cells: muscle
- Germ cells: oocytes and sperm
How are the stem cells said to set aside in the developing embryo for adult use?
It is thought that there are special mechanisms in the developing embryo that set aside these cells for use in the adult.
How long would RBC, white blood cells, skin, colon, sperm and brain cells last for?
Red blood cells live for about four months
White blood cells more than a year
Skin cells two or three weeks
Colon cells about four days
Sperm cells about three days
Many brain cells can last an entire lifetime
Why is stem cell maintenance so important?
Stem cell maintenance is a tightly regulated process that ensures the long-term survival and functionality of these essential cells. By understanding the underlying mechanisms, we can potentially harness their therapeutic potential for regenerative medicine and age-related diseases.
What is stem cell maintenance?
Stem cell maintenance is the process by which stem cells preserve their unique properties by dividing and differentiating
What is the main aim of stem cell maintenance?
It’s main role is to maintain the same stem cell population
Explain the division of stem cells
- There are three sorts of division.
- division rates must be balanced so as to keep stem cell population constant
Does the epidermis needs to be continually renewed?
Yes
What are the three main layers of the skin?
Epidermis - Made up of keratinocytes
Dermis - Contains fibroblast and blood vessels.
Subcutis.
What stimulates keratinocyte proliferation?
Signals from the dermis and basement membrane stimulate keratinocyte proliferation.
Which layer of the skin contains the stem cells?
The basal layer contains the stem cells that proliferate.
The daughter cells are pushed progessively to the skin surface where they die
What is produced that provides strength to the skin and moves towards the surface
Cells produce high levels of the fibrous protein keratin that provides strength to the skin
Cells produce different keratins as they move towards the surface.
What inhibits differentiation and maintains the stem cell population?
Wnt signals from the dermis inhibits differentiation (maintains stem cell population).
What are wnt signals?
Wnt signals represent a complex and highly conserved group of signal transduction pathways that are fundamental to a wide range of biological processes
What is the role of integrin?
Integrins (adhesion molecules) hold cells to the basement membrane (maintains stem cell population).
What inhibits integrins?
Notch signals in maturing keratinocytes inhibit integrins.
What inhibits Notch activity?
EGF inhibits notch
How does Egf maintain stem cell maintenance?
Egf inhibits Notch activity, which inhibits integrins, which are responsible for holding cells to the basement membrane which ultimately decreases stem cell population
What is the stem cell niche in the epidermis?
The basal layer of the epidermis is a stem cell niche
What is the stem cell niche called in the hair follicle
There is another stem cell niche in the hair follicle called the bulge.
What forms the follicles?
The stem cells from the bulge forms the follicles.
What happens when the skin is badly damaged and needs replacement?
When skin is badly damaged, there is a greater need for replacement cells. In this situation, bulge cells can also contribute to epidermis and sebaceous glands.
