Wound healing + repair

Question 1

What is the proliferative activity of labile cells?

Answer 1

Continuously dividing

Question 2

What is the proliferative capacity of stable cells?

Answer 2

Quiescent / minimal baseline proliferative capacity

Question 3

What stage of the cell cycle are stable cells in?

Answer 3

G0

Question 4

What is the proliferative capacity of permanent cells?

Answer 4

Terminally differentiated / non-proliferative

Question 5

What are the first 4 stages of wound healing?

Answer 5

Haemostasis
Inflammation
Proliferation
Remodelling

Question 6

What kind of clot forms in haemostasis?

Answer 6

Fibrin-fibronectin

Question 7

The inflammation stage of wound healing occurs how long after injury?

Answer 7

Within 72 hours of injury

Question 8

The proliferation stage of wound healing occurs how long after injury?

Answer 8

2-3 weeks after injury

Question 9

What is the aim of the inflammation stage of wound healing?

Answer 9

Clear debris and bacteria

Question 10

What is the aim of the proliferation stage of wound healing in the epidermis and dermis?

Answer 10

Epidermis - re-epithelialisation (regeneration)

Dermis - granulation tissue formation (scarring)

Question 11

How does the location of proliferation of keratinocytes differ in wound healing?

Answer 11

Proliferation can occur in suprabasal layers to accelerate healing

Question 12

Cell proliferation in wound healing is driven by which 2 things?

Answer 12

Growth factors

ECM signals

Question 13

Describe how growth factors stimulate cell proliferation.

Answer 13

Growth factors bind to growth factor receptors - this stimulates the production of cyclins and cyclin-dependent kinases

These proteins regulate sequential phosphorylation of enzymes, pushing the cell through different stages of the cell cycle

Question 14

What are the 5 main growth factors?

Answer 14

Epidermal growth factor (EGF)

Vascular endothelial growth factor (VEGF)

Platelet-derived growth factor (PDGF)

Fibroblast growth factor (FGF)

Transforming growth factor (TGF-B)

Question 15

Angiogenesis is mediated by which growth factor?

Answer 15

VEGF

Question 16

In angiogenesis, what happens to the basement membrane, how, and what is the purpose of this?

Answer 16

Degraded by matrix metalloproteinases (MMPs) - allows the formation of sprouts from the vessel

Question 17

What are the first 2 substances that fibroblasts produce during proliferation?

Answer 17

Fibronectin

Hyaluronan

Question 18

During proliferation, which cell type anchors to fibronectin and what do they do?

Answer 18

Myofibroblasts - wound contraction to help facilitate closure

Question 19

Describe how collagen deposition changes in the dermis during healing.

Answer 19

Type III collagen is laid down initially, which is then replaced by Type I collagen

Question 20

List 3 main roles of TGF-B in the dermis during proliferation.

Answer 20

Fibroblast migration and proliferation

Inhibits ECM degradation

Anti-inflammatory

Question 21

During remodelling, wound strength increases due to which 2 factors?

Answer 21

Collagen crosslinking

Increased size of collagen fibres

Question 22

Collagen synthesis occurs how many days after injury?

Answer 22

3-5 days

Question 23

What causes the size of scars to reduce?

Answer 23

Activity of MMPs

Question 24

Regeneration of epithelia of intestinal tract and skin is possible when?

Answer 24

If basement membrane is intact, i.e. only epidermis was injured

Question 25

Up to how many weeks of gestation does scarless healing occur in the foetus?

Answer 25

24 weeks gestation

Question 26

Does scarless healing in a foetus involve increased or decreased angiogenesis?

Answer 26

Decreased angiogenesis

Question 27

Which cells in the liver secrete cytokines to increase cell proliferation after injury?

Answer 27

Kupffer cells

Question 28

When hepatocyte proliferation is impaired, which cell type contributes to repopulation?

Answer 28

Stem cells

Question 29

What is the potency of adult stem cells?

Answer 29

Multipotent

Question 30

What is the potency of a fertilized egg?

Answer 30

Totipotent

Question 31

What is the potency of embryonic stem cells?

Answer 31

Pluripotent

Question 32

What can totipotent stem cells differentiate into?

Answer 32

Any cell type, including extra-embryonic tissues (placenta)

Question 33

What can pluripotent stem cells differentiate into?

Answer 33

Any cell type, but not extra-embryonic tissues

Question 34

What can multipotent stem cells differentiate into?

Answer 34

Lineage restricted, typically within a specific tissue or organ system

Question 35

Does more scarring occur in healing by first or second intention?

Answer 35

Second intention

Question 36

Glucocorticoids can alter healing by affecting the production of which growth factor?

Answer 36

TGF-B

Question 37

A wound qualifies as chronic if it fails to heal within how many months?

Answer 37

3 months

Question 38

In chronic wounds, what do keratinocytes not do?

Answer 38

Migrate

Question 39

Give 2 examples of types of excessive scarring.

Answer 39

Hypertrophic scars Keloid scars

Question 40

Hypertrophic scars are abundant in which kind of cell?

Answer 40

Myofibroblasts