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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.

• 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

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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

Therapeutic Cloning

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.

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

Bone marrow stromal cells

Differentiation of embryonic cells and generation of tissue cells by bone marrow precursors

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

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

• C-myc

• C-jun

• C-fos

• p53

ECM and Cell-Matrix interaction