Stem Cell pengertian stem cell

1. Tissue Renewal and Repair:
Regeneration, Healing, and Fibrosis
Siti zahara Saragih
Sri Hartati
Wenny Pintalitna
Yeni Nastuti

2. Tissue response to injury
Repair after injury can occur by regeneration, which restores normal tissue,
or by healing, which leads to scar formation and fibrosis.

3. • Regeneration refers to growth of cells and
tissues to replace lost structures, such as the
growth of an amputated limb in amphibians.
• Healing is usually a tissue response
• (1) to a wound (commonly in the skin),
• (2) to inflammatory processes in internal organs,
• (3) to cell necrosis in organs incapable of
regeneration.

4. Mechanisms regulating cell populations. Cell numbers can be altered by increased or decreased rates of
stem cell input, by cell death due to apoptosis, or by changes in the rates of proliferation or
differentiation

5. • In continuously dividing tissues (also
called labile tissues) cells proliferate
throughout life, replacing those that are
destroyed.
• In most of these tissues, mature cells are
derived from stem cells, which have an
unlimited capacity to proliferate and whose
progeny may undergo various streams of
differentiation.

6. • Nondividing (permanent) tissues contain
cells that have left the cell cycle and
cannot undergo mitotic division in
postnatal life.
• To this group belong neurons and skeletal
and cardiac muscle cells.

7. Repair by Healing, Scar Formation, and Fibrosis
• Induction of an inflammatory process in response to the
initial injury, with removal of damaged and dead tissue
• Proliferation and migration of parenchymal and
connective tissue cells
• Formation of new blood vessels (angiogenesis) and
granulation tissue
• Synthesis of ECM proteins and collagen deposition
• Tissue remodeling
• Wound contraction
• Acquisition of wound strength

8. The repair process is influenced by many factors, including:
• The tissue environment and the extent of tissue damage
• The intensity and duration of the stimulus
• Conditions that inhibit repair, such as the presence of foreign bodies
or inadequate blood supply,
• Various diseases that inhibit repair (diabetes in particular), and
treatment with steroids

9. Formation of a scar
• (1) emigration and proliferation of fibroblasts in the site of injury
• (2) deposition of ECM
• (3) tissue remodeling

10. Formation of a scar
• (1) emigration and proliferation of fibroblasts in the site of injury
• (2) deposition of ECM
• (3) tissue remodeling