Healing and repair

• Repair


  Restoration of tissue architecture and function after an injury
• Healing


  Restoration of surface epithelium after an injury
• Regeneration


  Restoration of normal cells
• Scarring


  Connective tissue deposition
• Repair occurs via regeneration or scarring
• Factors affecting repair process

  • Proliferative capacity of cells
  • Interaction between cells and extracellular matrix
  • Development of mature cells by progenitor/stem cells
• Cell types that proliferate during repair

  • Remnants of injured tissue
  • Vascular endothelial cells
  • Fibroblasts
• Labile tissue


  Continuously dividing tissue
• Stable tissue


  Tissue with cells in quiescent (G0) phase, can proliferate in response to injury
• Stable tissues


  • Parenchyma of solid organs
  • Endothelial cells
  • Fibroblasts
  • Smooth muscle cells
• Permanent tissue


  Terminally differentiated, non-proliferative cells in postnatal life
• Permanent tissues


  • Neurons
  • Cardiac muscle
  • Skeletal muscle
• Liver regeneration


  • Proliferation of remaining hepatocytes
  • Repopulation from progenitor cells
• Proliferation of remaining hepatocytes

  1. Priming phase

  2. Growth factor phase

  3. Termination phase
• Progenitor cells


  Stem cells that can repopulate liver when hepatocyte proliferation is impaired
• Progenitor cells reside in the Canal of Hering