Wound Healing

Question 1

What are labile cells?

Answer 1

cells that proliferate throughout their life (epithelial cells, hematopoietic cells)

Question 2

What are stable cells?

Answer 2

cells that proliferate in response to a stimuli (fibroblasts, smooth muscle cells, osteoblasts, chondrocytes)

Question 3

What are permanent cells?

Answer 3

cells that cannot proliferate (nerve cells skeletal and cardiac cells)

Question 4

Where is tissue repair possible?

Answer 4

in tissues where there are lablie cells and stable cells

Question 5

What are the cell responses to injury? (there are 6 of these)

Answer 5

1. atrophy (decrease in cell number for function)
2. hypertrophy (increase in cell size)
3. hyperplasia (increase in cell number)
4. metaplasia (change in cell type)
5. change in phenotype (change in type of number of proteins expressed)

Question 6

What is stress shielding?

Answer 6

bone loss due to implants having a higher Youngs modulus

Question 7

What is intimal hyperplasia?

Answer 7

increased numbers of smooth muscle cells that lead to the narrowing of blood vessels

Question 8

Where are the important growth factors released from?

Answer 8

leukocytes, platelets

Question 9

Which growth factors do neutrophils produce?

Answer 9

proinflammatory cytokines and IL-1 which is critical for connective tissue repair

Question 10

Which growth factors to macrophages produce?

Answer 10

fibroblast GF, platelet-derived GF and vascular endothelial GF

Question 11

What happens in the proliferation and repair stage of wound healing?

Answer 11

• the growth factors released by platelets are degraded by proteases but are replaced by the growth factors produced by the macrophages and neutrophils
• this means that fibroblasts, endothelial cells, epithelial cells, epidermal are all recruited to the site of the wound

Question 12

How do cells know how to proliferate?

Answer 12

the absence of cells around a cell causes proliferation. this is mediated by adhesion molecules

Question 13

What happens in the ECM formation stage of wound healing? what does this tissue look like?

Answer 13

• fibroblasts make ECM
• angiogenesis
• the acidic environment stimulates capillary growth
• proliferation, organisation and proliferation of endothelial cells
• it is red a granular because of the red blood cells
• wound contracts

Question 14

What happens in the remodelling phase?

Answer 14

• cells undergo apoptosis and mean that acellular scar tissue replaces the granulation tissue
• ECM gets remodelled by collagen synthesis and degradation

Question 15

What are chronic non-healing wounds

Answer 15

the wound healing never leaves the inflammatory stage