Healing & Repair

Question 1

What are the differences between regeneration & repair?

Answer 1

Regeneration - Replacement with functional ‘differentiated’ cells

Repair - Fibrous scar production, changes in tissue structure

Question 2

Mention cells involved in healing and repair

Answer 2

• Labile cells - ✅
  Normal state - active cell division
  Rapid regeneration
  Examples → Oral keratinocytes
• Stable cells - ✅
  Variable regeneration rates
  Rapid proliferation → in response to injury
  Examples → Lfibroblast
• Permanent cells - 🔧
  Unable to divide or regenerate
  Examples → nerves fibres

Question 3

What are the 4 stages of healing and repair?

Answer 3

1-Coagulation phase
2-Inflammation phase
3-Proliferative phase
4-Maturation phase

Question 4

What happens in coagulation phase?

Answer 4

Clot formation arises through coagulation cascade Mitosis of labile and stable cells

Question 5

What happens in inflammation phase?

Answer 5

-Immune cell recruitment
-Infectious agent is degraded and cleared via macrophages & neutrophils.
-Fibroblasts & keratinocytes stimulated to initiate repair/regeneration

Question 6

What happens in Proliferation phase?

Answer 6

Formation of granulation tissue (rich in collagen)
Growth factors are essential
Fibroblasts are key players
Angiogenesis
Myofibroblasts help healing

Question 7

What is angiogenesis?

Answer 7

Formation of new blood vessel

Question 8

What are the differences between 1st and 2nd phase of proliferation ?

Answer 8

First phase – rich in vasculature
-Newly formed capillaries, immune cells, fibroblasts.

Second phase – rich in collagen (called fibrous granulation tissue)
-Capillaries regress
-Mature fibroblasts create collagen

Question 9

How ECM being re-modeled?

Answer 9

by matrix metalloproteinases (MMPs)

Question 10

What is Growth Factors ?

Answer 10

Signaling molecules that promote or inhibit cell growth and/or cell differentiation

Question 11

How Growth factors can be produced?

Answer 11

• Microbial recognition
• Cytokine signalling

Question 12

What is Angiogenesis?

Answer 12

Formation of new capillaries

Question 13

What is the role of VEGF?

Answer 13

Promote formation of new blood vessels

Question 14

What are the 2 process of forming new blood vessels?

Answer 14

-Sprouting
-Splitting

Question 15

What is fibrosis?

Answer 15

Deposition of collagen and formation of fibrous connective tissue

Question 16

Fibrosis a process driven by ?

Answer 16

Fibroblasts

Question 17

What is the role of macrophage in fibrosis?

Answer 17

control fibroblast function through different
subsets – M1(tissue injury) and M2 (tissue repair)

Question 18

What happened in maturation phase?

Answer 18

Tissue remodelling: Granulation tissue remodelled, collagen fibres cross-linked, Re-epithelization, Regain of tensile strength, Fibrous scar (in repair🔧)

Question 19

What oesteoblast secrete?

Answer 19

RANKL & OPG

Question 20

What is the role of OPG?

Answer 20

Osteoprotogerin (OPG) inhibits RANKL function – therefore controlling bone resorption

Question 21

What is the result occurs in an imbalanced process of bone remodeling (osteoblasts/osteoclast)?

Answer 21

Periodontitis

Question 22

What is Hematoma?

Answer 22

Formation of blood clot within the tissue/bone

Question 23

What happens on proliferation phase of fracture healing?

Answer 23

Formation of granulation tissue
GTs becomes the fibrocartilage callus which composed of osteoblasts, fibroblasts and chondrocytes
Granulation tissue is ossified

Question 24

What happens in maturation phase in fracture healing?

Answer 24

Osteoclasts and osteoblasts remodel the bone callus Cortical replaces woven bone