Tissue Repair

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Tissue Repair

• Regeneration,
• repair healing
• of injured tissues

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Repair responses following Injury/Inflammation
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Regeneration

• Growth of cells and tissues to replace lost
  structures
• Requires an intact connective tissue scaffold

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Regulation of cell populations
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TYPES OF CELLS

• Labile cells
• Stable cells
• Permanent cells

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Labile cells

• have a high rate of loss and replacement and
  therefore high capacity for regeneration.
• squamous and glandular epithelia
• haemopoeitic cells in bone marrow

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Stable cells

• do not normally proliferate but can be stimulated
  to do so after damage.
• renal tubular cells,
• hepatocytes,
• osteoblasts,
• endothelial cells,
• fibroblasts.

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Permanent cells

• Permanent cells unable to divide after initial
  development and therefore cannot regenerate when
  some are lost.
• Neurons
• Skeletal cardiac muscle

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Cell Cycle
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Dolly the sheep, the first cloneIan Wilmut, who
led the team that created Dolly at Scotland's
Roslin Institute in 1996 Dolly Parton(singer)
after whom the sheep was named
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STEM CELLS

• Regenerative Medicine
• Stem Cells are characterised by their prolonged
  self renewal capacity and by their asymmetric
  replication
• Embryonic / Adult Stem cells

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EMBRYONIC STEM CELLS

• Pluripotent cells that give rise to all tissues
  of the body
• To develop Knockout mice
• To repopulate damaged organs

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Therapeutic Cloning
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Stem Cell Research

• The Pros
• large potential for finding treatments and cures
  to a vast array of diseases cancers diabetes,
  spinal cord injuries, Alzheimer's, MS,
  Huntington's, Parkinson's and many more.
• The use of adult-derived stem cells, from blood,
  skin and other tissues, has been demonstrated to
  be effective for treating different diseases in
  animal models.
• Umbilical cord-derived stem cells have also been
  isolated and utilized for various experimental
  treatments.

• The Cons
• The major con to stem-cell research is from the
  religious stance that life begins at conception
  and to destroy it to be used for research is
  immoral and wrong. Currently, the use of
  embryonic stem cells for research involves the
  destruction of the blastocysts formed from
  laboratory-fertilized human eggs.

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ADULT STEM CELLS

• More restricted differentiation capacity
• Usually lineage specific
• Located in sites called Niches
• Bone Marrow Haematopoietic stem cells
• Bone Marrow Stromal stem cells
• Transdifferentiation / Developmental plasticity
• Multipotent Adult Progenitor Cells

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Stem Cell Niches
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Bone marrow stromal cells
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Differentiation of embryonic cells and generation
of tissue cells by bone marrow precursors
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Growth Factors

• Polypeptides
• Some act on many cell types
• Others act on restricted cellular targets
• Cell locomotion, contractility, differentiation,
  angiogenesis, growth receptors and transcription
  factors

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Signaling mechanisms in Cell Growth
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Signal Transduction Pathways

• Receptors with Tyrosine kinase activity
• Receptors lacking Tyrosine kinase activity
• Seven transmembrane G-protein coupled receptors
• Steroid Hormone receptors

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Transcription Factors

• C-myc
• C-jun
• C-fos
• p53

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ECM and Cell-Matrix interaction
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