Stem Cells and Apoptosis

Apoptosis and Cellular Death

• Apoptosis (programmed cell death)

  • Vital for fetal development

  • Necessary for the growth of placenta and embryo

  • Prevents the formation of webbed hands and feet in embryos

• Induced by various internal and external factors:

  • Heat stress from burns leads to cell death and regeneration of skin

  • Immune cells (cytotoxic T cells) trigger apoptosis in infected cells to inhibit virus replication including COVID-19.

Types of Cell Death

• Apoptosis

  • Intrinsic Pathway: Damage to mitochondria signals for cell death.

  • Extrinsic Pathway: External signals detected by death receptors lead to apoptosis.

  • Highly controlled and regulated process:

    • Nobel Prize awarded for discovering control mechanisms in apoptosis.

    • Results in formation of apoptotic bodies for clean disposal by immune cells.

• Necrosis

  • Involves rupture of cell membrane often due to extreme conditions (high/low pH, temperature).

  • Leads to uncontrolled cell death.