Lecture 28: Tissue renewal, repair and regeneration

Question 1

What is the difference between tissue regeneration and tissue repair?

Answer 1

Tissue regeneration: replacement of injured tissue with cells of the SAME type and FUNCTION.

Tissue repair: Occurs when extent or nature of damage cannot be reversed by regeneration alone.

Question 2

What are the 4 stages of healing after tissue injury?

Answer 2

Hemostasis: This happens in minute resulting in local vasoconstriction and clotting factors to form a fibrin clot.

Inflammation: This happens in hours with it being driven by platelet-derived mediators, bacteria and secreted chemoattractants.

Proliferation: This takes days to happen and it is mediated by macrophage/fibroblast-derived growth factors.

Remodeling: This takes weeks to months and is a transition from type 3 to type 1 collagen.

Question 3

What are the determinants of regeneration versus repair after tissue injury?

Answer 3

The nature of cells injured

Extent of the injury

Presence or absence of ongoing inflammation

Underlying disease

Question 4

What are the common outcomes of various signal transduction pathways of growth factors?

Answer 4

The common outcome is a change in gene transcription

Question 5

What are the two forms of ECM and their key components?

Answer 5

Basement membrane
Components:
-Type 4 collagen
-Laminin
-Proteoglycan

Interstitial matrix
-Fibrillar collagens
-Elastin
-Proteoglycan and hyaluronan

Question 6

What are the three key growth factors that regulate fibrosis?

Answer 6

PDGF (platelet-derived growth factor)

TGFBeta (transforming growth factor)

FGF-1 (fibroblast growth factor)