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Developmental, Stem Cell & Regenerative biology > Lecture 6 - The stem cell niche > Flashcards

Lecture 6 - The stem cell niche Flashcards

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1
Q

Describe the potency of stem cells initially in the embryo?

A

Totipotent

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2
Q

What cells are produced from mesenchymal stem cells?

A
  • bone cells (osteoblasts)
  • cartilage cells (chondrocytes)
  • fat cells (adipocytes)
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3
Q

What cells are produced from haematopoetic stem cells?

A
  • blood stem cells
  • red blood cells
  • platelets
  • white blood stem cells
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4
Q

What cells are produced from satellite stem cells?

A

muscle

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5
Q

What cells are produced from germ cells?

A
  • oocytes
  • sperm
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6
Q

What is the name given to the special environments where adult stem cells are found?

A

niches

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7
Q

Why do we need stem cells?

A

maintenance

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8
Q

How long do RBC live for?

A

4 months

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9
Q

How long do white blood cells live for?

A

> a year

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10
Q

How long do skin cells live for?

A

2-3 weeks

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11
Q

How long do colon cells live for?

A

4 days

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12
Q

How long do sperm cells live for?

A

3 days

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13
Q

How long do brain cells last?

A

can live for an entire lifetime

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14
Q

What process allows stem cell to carry out maintenance?

A

mitosis

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15
Q

How is stem cell division different from normal mitosis?

A

creates a daughter cell and keeps a stem cell

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16
Q

What is the advantage of stem cell division compared to normal mitosis?

A

maintains the stem cell population

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17
Q

What is the name of the stage by which the daughter cell, created through stem cell division, differentiates to create many cells?

A

transit amplifying stage

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18
Q

What is population asymmetry?

A

3 different types of division to ensure that division rates are in balance that keep the stem cell population constant

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19
Q

What are the 3 types of cell division which maintains population asymmetry?

A
  1. stem cell proliferates into 2 stem cells
  2. stem cell proliferates into 2 differentiated cells
  3. stem cell proliferates into one of each
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20
Q

What are the 3 main layers of the skin?

A

epidermis, dermis & subcutis

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21
Q

What can be found in skin?

A
  • hair follicles
  • sebaceous glands
  • sweat glands
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22
Q

What is the epidermis made up of?

A

keratinocytes

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23
Q

What does the dermis contain?

A

fibroblasts & blood vessels

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24
Q

What stimulates keratinocyte proliferation?

A

signals from the dermis & basement membrane

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25
Q

What type of stem cells (that can proliferate) can be found in the stem cell niche that is the basal layer?

A

basal keratinocytes

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26
Q

What happens to the daughter cells (basal keratinocytes) when they proliferate?

A

pushed progressively to the skin surface where they die

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27
Q

What provides the skin with strength?

A

high levels of fibrous protein keratin

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28
Q

What happens to cells as they move towards the surface?

A

produce different keratin

29
Q

Where are dead keratinocytes found?

A

on the outer layer of the skin

30
Q

What separates & holds the dermis and epidermis together?

A

extracellular matrix

31
Q

What signals come from the dermis that impacts differentiation?

A

Wnt

32
Q

How does Wnt (from dermis) impact differentiation?

A

Wnt inhibits differentiation, which maintains stem cell population

33
Q

How does Integrins maintain stem cell population?

A

Integrins hold cells to the basement membrane. This adhesion allows for the maintenance of stem cell population.

34
Q

How do notch signals influence the maintenance of stem cell population?

A

Notch signals in maturing keratinocytes inhibit integrins. This stops adhesion between cells and the basement membrane. As a result, this causes a reduction in stem cell populations.

35
Q

What is the protein that can inhibit Notch signal activity?

A

EGF (epidermal growth factor)

36
Q

What is the stem cell niche located in the hair follicle?

A

the bulge

37
Q

What is the purpose of the bulge found in the hair follicle?

A

Provide the cells that form the follicle

38
Q

What can bulge cells contribute when skin is badly damaged?

A

bulge cells can also contribute to epidermis & sebaceous glands, which can aid in the replacement of damaged skin.

39
Q

What occurs as a whole to stem cell niches after injury, when larger areas of restoration are needed?

A

different stem cell niches may be able to provide cells

40
Q

What occurs in patients with Junctional epidermolysis bullosa (JEB)?

A

the adhesion between dermis and epidermis is impaired, due to mutation in adhesion genes - LAMB3

41
Q

What can be used to replace skin in burn patients?

A

Skin epidermis (basal keratinocytes) that have been cultured

42
Q

What can be used to reintroduce DNA into cells, when skin epidermis have been cultured from JEB patients?

A

inactivated viruses (viral vectors)

43
Q

Why does our gut lining need to be continuously replenished?

A

Due to the harsh environment created due to our gut content

44
Q

What are the different types of cells found in the small intestine?

A
  • enterocyte
  • goblet cells
  • enteroendocrine cells
  • paneth cells
  • stem cells
  • submucosal cells
45
Q

What process are enterocyte cells involved in?

A

absorption

46
Q

What is the function of goblet cells?

A

Secrete mucus

47
Q

What is the function of enteroendocrine cells?

A

secrete peptide hormones

48
Q

What is the function of Paneth cells?

A

secrete anti-microbial peptides

49
Q

What is the function of submucosal cells?

A

help maintain the stem cells

50
Q

Where are stem cells located?

A

base of the crypt

51
Q

How many cells does each crypt create in a mouse?

A

12 cells per hour

52
Q

How many cells is a crypt made up of?

A

250 cells

53
Q

What hormone does slow-dividing stem cells express?

A

Bim1

54
Q

What hormone does fast-dividing stem cells express?

A

Lgr5

55
Q

What are Bim1 & Lgr5 markers for?

A

Stem cells

56
Q

How do we know that Lgr5 positive cells are stem cells?

A

Lineage tracing allows us to determine the fate of a cell

57
Q

What can be made that causes single cells to express a marker?

A

Transgenes

58
Q

How can embryonic stem cells be grown?

A

they can be isolated from the epiblast & grown in cell culture

59
Q

How is the embryonic stem cells kept in a pluripotent state?

A

They are kept in specially defined conditions, with BMP & LIF present

60
Q

What occurs if BMP & LIF signals were removed from the embryonic stem cells?

A

this would lead to differentiation into different cell types - each cell type requiring a specific set of conditions.

61
Q

What is the difference between human and mouse ES cells?

A

human - pluripotent & require FGF + activin
mouse - totipotent & require different treatment (BMP & LIF)

62
Q

What are the assays (tests) for pluripotency?

A

Expression of epiblast markers (transcription factors):
- Nanog
- Oct4
- Sox2
- Klf4

63
Q

How are chimeras made?

A

created when ES cells are mixed in with a normal embryo & the ES cells contribute to different tissues in the adult

64
Q

What are teratomas?

A

benign tumours that contain differentiated tissues

65
Q

What occurs if we activate epiblast marker expression in differentiated cells?

A

the cells dedifferentiate and become stem cells

66
Q

What factors are used to convert differentiated cells into IPS cells (induced pluripotent stem cells)?

A

Yamanaka factors

67
Q

What is the advantage of using Yamanaka factors to create IPS cells instead of ES cells?

A

Ethically less complex - ES cells can be quite difficult to obtain

68
Q
A

Developmental, Stem Cell & Regenerative biology (15 decks)

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