Wound Healing And Repair Flashcards
(21 cards)
Repair in 2 ways
Regeneration and scar formation
Cells that have function in repair
In regeneration
Uninsured cells
Stem cells
In scar formation
Connective tissue cells
Fibrosis
Extensive deposition of collagen
• Lungs, liver, kidney
• Consequence of chronic inflammation
• Myocardium
• Extensive ischemic necrosis (infarction)
Cell number in normal
tissue is determined by
proportion of;
• Proliferation
• Death (apoptosis)
• Differentiatio
Cell types proliferating during tissue repair
The remnants of injured tissue
Vascular endothelial cells
Fibroblasts
Proliferative Capacities of Tissues
- Labile (continuously dividing) tissues
• hematopoietic cells in the bone marrow
• surface epithelia, ducts
• Gastrointestinal, Genitourinary tract
• These tissues can readily regenerate after injury as long as the pool of stem cells is preserved. - Stable tissues
• capable of proliferating in response to injury or loss of tissue mass
• liver, kidney, and pancreas.
• endothelial cells, fibroblasts, and smooth muscle cells
• limited capacity to regenerate after injury
• Liver has much more capacity - Permanent tissues
• terminally differentiated and nonproliferative in postnatal life
• Neurons
• Limited stem cell replication and differentiation
• Cardiac muscle cells
• some evidence, may proliferate after myocardial necrosis
• Skeletal muscle
• satellite cells attached to the endomysial sheath
Stem cells show ….. replication
Asymmetric
Cells can differentiate to any cell type
Pluripotent stem cells
Cells have ability to differentiate a cell type within a particular lineage
Multiporent stem cells
Types of Stem Cells
- Embryonic stem cell (ESC)
- Adult (somatic) stem cells
- Induced pluripotent stem
cells (iPSC)
Adult stem cells’ lineage potential is restricted to
Tissue organ
An intact ECM is required for tissue regeneration
• If the ECM is damaged
Scar formation
• Steps in scar formation
Injury and Inflammatory
response
• Granulation tissue
• Angiogenesis
• Migration and proliferation of
fibroblasts
• Deposition of connective tissue
• Remodelling
• Maturation and reorganization
of the fibrous tissue
• Stable fibrous scar
24 hours of injury
Angiogenesis
• emigration of fibroblasts
• induction of fibroblast and endothelial cell proliferation
Granulation Tissue (3 to 5 days)
• abundant vessels
• interspersed leukocytes
• pink, soft, granular appearance macroscopically
• such as that seen beneath the scab of a skin wound.
Angiogenesis
• Growth factors
VEGF : stimulation of proliferation and migration of
endohelial cells. Vasodilatation ( stimulates production of NO)
helps to formation of vascular lümen
• FGFs: stimulation of endothelial proliferation. Migration of
machrophages and fibroblasts to the injury site. Stimulates
epithelial cells to migrate to the injury site for wound closure
• Angiopoetin 1 ve 2: maturation of new vessels.
• PDGF: stabilisation of smooth muscle cells
• TGF-B: inhibits endothelial proliferation ond migration,
stimulates production of ECM protein
Notch signalling
through‘cross-talk’ with VEGF
• Regulates the sprouting and branching of new vessels
• Ensures that new vessels have the proper spacing to
effectively supply the healing tissue with blood
Macrophages
• Digestion of microbial agents
and dead tissue
• Production of growth factors
• Production of cytokines to
stimulate proliferation of
fibroblasts
• Production of cytokines in
synthesis and deposition of
connective tissue
• Transforming growth factor-β (TGF-β)
the most important cytokine for
the synthesis and deposition of connective tissue proteins.
Degradation of collagens with
Metalloproteinases
