Wound Healing and Angiogenesis

Question 1

What factor determines whether an inflammatory reaction heals by regeneration or fibrosis.

Answer 1

Extent of the damage and whether or not the tissue has regenerative capacity. (For example, muscle cannot regenerate, but the liver can.)

If the original tissue structure still exists or there is persistent tissue damage.

Question 2

What are the 5 components of fibrosis.

Answer 2

1. Angiogenesis
2. Inflammation
3. Fibroblast Migration and Proliferation
4. Scar Formation
5. Connective Tissue Remodeling

Question 3

What are the two mechanisms of angiogenesis?

Answer 3

a. Endothelial precursor cells

b. From existing blood vessels
i. Vasodilation
ii. Proteolytic degradation of the vessel basement membrane
iii. Migration of endothelial cells towards hypoxic signals
iv. Proliferation of endothelial cells
v. Maturation of endothelial cells

Question 4

Describe Endothelial precursor cells (EPCs) in their role of angiogenesis.

Answer 4

EPCs migrate from bone marrow, differentiate, and form blood vessles

Question 5

Describe angiogenesis from existing blood vessels.

Answer 5

i. Vasodilation
ii. Proteolytic degradation of the vessel basement membrane
iii. Migration of endothelial cells towards hypoxic signals
iv. Proliferation of endothelial cells
v. Maturation of endothelial cells

Question 6

What is the most important growth factor involved in angiogenesis.

Answer 6

Vascular Endothelial Growth Factor

Question 7

What are the 2 types of cutaneous wound healing? be able to explain the type of injury that causes each one.

a. First intention
i. Sterile incision, closed wound, clean
b. Second intention
i. Dirty wound, open wound, substantial tissue defects

Answer 7

First Intention Healing

Second Intention Healing

Question 8

What type of injury causes First Intention Healing?

Answer 8

Sterile Incisions
Closed wounds
Clean wounds

(pretty things)

Question 9

What type of injury causes Second Intention Healing?

Answer 9

Dirty wounds
Open wounds
Substantial tissue defects

(nasty shit)

Question 10

Describe the progression of events in healing by first intention.

(Day 1, Day 3, Day 5, Week 2)

Answer 10

a. 24 hours: Wound fills with clotted blood containing fibrin, neutrophils appear, epidermis thickens, epithelial cells migrate to center.
b. Day 3: Transition from acute to chronic inflammation. Neutrophils replaced by macrophages. Granulation tissue forms from angiogenesis and fibroblast proliferation.
c. Day 5: Incision filled with granulation tissue, collagen fibrils bridge incision, epidermis returns to normal thickness.
d. Second week: Leukocytes, edema, and increased vascularity disappear, granulation tissue replaced by scar, remodeling of collagen, wound strength increases.

Question 11

What are the definition and morphological features of granulation tissue?

Answer 11

Granulation Tissue: Angiogenesis + fibroblast proliferation

Granulomatous Inflammation: Epithelioid macrophages and giant cells

Question 12

What are the major differences between 1st and 2nd intention healing.

Answer 12

Second intention healing has much more granulation tissue, leading to a larger scar.

There is a more intense inflammatory reaction and wound is closed by wound contraction of MYOFIBROBLASTS.