Wound Healing Flashcards
When does wound healing NOT result in scarring?
Foetus
When does wound healing result in scarring?
Late gestation onwards
What cells organise new tissue?
Stromal cells
What are the three basic cellular phases of wound healing?
Migration, proliferation, differentiation
Outline the process of wound healing
Initial acute inflammatory response
Parenchymal functional regeneration
Re-epithelialisation and cell migration
Proliferation of parenchyma and stromal cells
Synthesis of ECM proteins
Remodelling
What are the three classic stages of wound regeneration?
Inflammation - ~48h
- hypoxic + fibrin clot
- neutrophils and platelets
New tissue formation - ~2-10 days
- granulation tissue, angiogenesis
- reepithelialisation under scab, ECM synth
Remodelling - ~1year
- wound contracts, reepithelialised
- increased tensile strength, decreased cellularity and vascularity
How does the population of cell change during wound healing?
Platelets
Neutrophils
Macrophages
Fibroblasts + Lymphocytes
What occurs in coagulation?
Formation of fibrin clot
- platelets and inflammatory cells
Platelet deposition and aggregation
- platelet degranulation
- release of PDGF (Platelet derived GF) and TGFb (transforming GF)
What occurs in the inflammatory phase?
Neutrophils - matrix phagocytosis + free radical generation to limit infection
Macrophages KEY
- Debridement and matrix turnover
- Stimulatory signals/factors
Lymphocytes (later)
- important in early remodelling
What is the role of macrophages in wound healing?
Removal of debris Cell recruitment and activation Phagocytosis Angiogenesis -VEGF Matrix synthesis regulation - GFs, Cytokines (TNFa, IL-1, IFNy),
What is the difference between M1 and M2 macrophages?
M1 - proinflammatory, inhibitor of proliferation
M2 - anti-inflammatory, promoter of proliferation
What happens in first part of the the migration phase?
What happens next?
Single layer of Keratinocytes migrate under the fibrin clot
Differentiation and stratification of neodermis
Proliferation
Production of VEGF, TNFa (pro inflammatory) PDGF
What cells do you find on the surface of vessels ?
Pericytes
What conditions initiate angiogenesis?
Inflammation and hypoxia
What is the dominant cell type at the wound edge?
Fibroblast
