Chapter004

Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Chapter 4Cell Proliferation, Tissue Regeneration and Repair

Chapter 4Cell Proliferation, Tissue Regeneration and Repair


Cell Proliferation and Tissue RegenerationCell Proliferation and Tissue Regeneration

• Parenchymal tissue

• Stromal tissue


Cell Proliferation Versus DifferentiationCell Proliferation Versus Differentiation

• Cell proliferation-process of increasing cell numbers by mitotic division

• Cell Differentiation-process whereby a cell becomes more specialized in terms of structure and function


The Cell CycleThe Cell Cycle

• 4 distinct phases


Proliferative Capacity of TissuesProliferative Capacity of Tissues

• Varies with tissue and cell type

3 divisions of body tissues:

a.Continuously doubling

b.Stable

c.Permanent tissues


Stem CellsStem Cells

• Incompletely differentiated throughout life

3 Properties:

a.Self-renewal

b.Asymmetric replication

c.Differential potential (potency)


Influence of Growth FactorsInfluence of Growth Factors

• Small hormonelike proteins that increase cell size and cell division

• PDGF, FGF, TGF, and EGF


Extracellular Matrix and Cell-Matrix InteractionsExtracellular Matrix and Cell-Matrix Interactions

• ECM is secreted locally and assembles a network of spaces surrounding tissue cells

• Components of ECM:

a.Fibrous structural proteins

b.Water-hydrated gels

c.Adhesive glycoproteins


Components of the ECMComponents of the ECM


Healing by Connective Tissue RepairHealing by Connective Tissue Repair


Phases of RepairPhases of Repair

• Angiogenesis and ingrowth of granulation tissue

• Emigration of fibroblasts and deposition of extracellur matrix

• Maturation and reorganization of the fibrous tissue (remodeling)

Usually begins within 24 hours of injury; evidenced by the migration of fibroblasts and the induction of fibroblast and epithelial cell proliferation


Angiogenesis and Ingrowth of Granulation TissueAngiogenesis and Ingrowth of Granulation Tissue


Maturation and Remodeling of the Fibrous TissueMaturation and Remodeling of the Fibrous Tissue


Cutaneous Wound HealingCutaneous Wound Healing

• The transition from granulation to scar tissue shifts in the modification and remodeling of the ECM


Healing by Primary and Secondary IntentionHealing by Primary and Secondary Intention

• Primary intention –sutured surgical incision

• Secondary intention- larger wounds which have a greater loss of tissue and contamination


Phases of HealingPhases of Healing

• Inflammatory Phase

• Proliferative Phase

• Maturational or Remodeling


KeloidsKeloids


Factors that Affect Wound HealingFactors that Affect Wound Healing


Nutritional StatusNutritional Status

• Local and systemic factors influence wound healing

• Vitamin Ca and A play an essential role in the healing process

• Vitamin C is needed for collagen synthesis

• Vitamin A functions in stimulating and supporting epitheilial


Blood Flow and Oxygen DeliveryBlood Flow and Oxygen Delivery

• For healing to occur, wounds must have adequate blood flow to supply the necessary nutriients and to remove waste, local toxins, bacteria and other debris.


Wound Healing in the ElderlyWound Healing in the Elderly

• Age-related changes:

A decrease in dermal thickness

A decline in collagen content

Loss of elasticity

• Elderly are more vulnerable to chronic wounds, such as pressure, diabetic, and ischemic ulcers as compared to younger persons

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