Tissue Repair
Regeneration,
repair & healing
of injured tissues
Repair responses following Injury/Inflammation
Regeneration
Growth of cells and tissues to
replace lost structures
Requires an intact connective
tissue scaffold
Regulation of cell populations
TYPES OF CELLS
• Labile cells
• Stable cells
• Permanent cells
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
Stable cells
• do not normally proliferate but can be
stimulated to do so after damage.
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renal tubular cells,
hepatocytes,
osteoblasts,
endothelial cells,
fibroblasts.
Permanent cells
• Permanent cells : unable to divide after initial
development and therefore cannot regenerate
when some are lost.
• Neurons
• Skeletal & cardiac muscle
Cell Cycle
Dolly the sheep, the first clone
Ian Wilmut, who led the team that created Dolly at
Scotland's Roslin Institute in 1996
Dolly Parton(singer) after whom the sheep was named
STEM CELLS
Regenerative Medicine
Stem Cells are characterised by their
prolonged self renewal capacity and by
their asymmetric replication
Embryonic / Adult Stem cells
EMBRYONIC STEM CELLS
Pluripotent cells that give rise to all
tissues of the body
To develop Knockout mice
To repopulate damaged organs
Therapeutic Cloning
Stem Cell Research
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The Pros
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The Cons
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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.
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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
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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
Stem Cell Niches
Bone marrow stromal cells
Differentiation of embryonic cells and generation
of tissue cells by bone marrow precursors
Growth Factors
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Polypeptides
Some act on many cell types
Others act on restricted cellular targets
Cell locomotion, contractility,
differentiation, angiogenesis, growth
receptors and transcription factors
Signaling mechanisms
in Cell Growth
Signal Transduction Pathways
• Receptors with Tyrosine kinase activity
• Receptors lacking Tyrosine kinase activity
• Seven transmembrane G-protein coupled
receptors
• Steroid Hormone receptors
Transcription Factors
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C-myc
C-jun
C-fos
p53
ECM and Cell-Matrix interaction