Repair

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Repair

• Recovery from Injury

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Repair

• Bodys attempt at restoring normal structure
  function

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Cells Regenerative Ability
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Tissue Structure

• Regeneration requires intact stromal framework,
  otherwise get scarring
• Basement membrane
• Extracellular matrix

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Cell Reproduction Tissue Growth

• Governed by protooncogenes
• Stimulate production of growth factors
• Growth factors are proteins that regulate cell
  regeneration scar production
• Epidermal growth factor
• From platelets macrophages
• Vascular endothelial growth factor
• From mesenchymal cells
• These are influenced by the extracellular matrix

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Wound Healing Fibrous Repair

• Repair by regeneration is ideal
• Healing is when regeneration is not possible or
  is incomplete
• fibrous repair

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Cell Migration

• Begins within hours of injury
• Leukocytes limit damage clean up
• cytokines for stimulation of fibroblasts
• New capillaries
• Fibroblasts fill in space not occupied by
  parenchyma

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Angiogenesis

• Stimulated by vascular endothelial growth factor

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Scar Development

• After angiogenesis
• Initially, there is the formation of granulation
  tissue
• Capillaries, fibroblasts, leukocytes
• Size of wound determines how long it persists
• Fibroblasts contract pulling edges of wound
  closer together produce collagen to bind
  strengthen wound
• Fluid resorbed, more collagen
• Reshaped by mechanical forces
• Size of wound determines whether you heal by
  first (primary) intention or second (secondary)
  intention

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Host Factors that Interfere With Healing

• Infection
• most frequent cause
• Poor nutrition
• Steroids
• Poor blood supply
• Foreign bodies
• Mechanical factors

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Dehiscence

• Rupture due to tension

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Ulceration

• No epithelium covering

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Pathologic Wound Healing

• Keloid formation
• Hyperplastic scar
• Genetic predisposition
• Excess granulation tissue
• Pyogenic granuloma

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• Acute injury
• complete regeneration
• mixture of regeneration fibrosis
• fibrosis
• Persistent injury
• chronic inflammation fibrosis