Tissue Homeostasis: Stem cells maintain the stability of internal environments by replacing cells that are lost to natural wear and tear or programmed cell death.
Growth and Development: During the transition from embryo to adult, stem cells provide the necessary cellular building blocks for expanding organs and systems.
Regenerative Repair: In response to injury, stem cells are activated to divide and differentiate, filling gaps in damaged tissue and restoring functional integrity.
| Feature | Embryonic Stem Cells | Adult Stem Cells |
|---|---|---|
| Potency | Pluripotent (can become almost any cell) | Multipotent (limited range of cells) |
| Source | Early-stage embryos (blastocysts) | Various tissues (e.g., bone marrow, skin) |
| Primary Role | Formation of all body tissues | Maintenance and repair of specific tissues |
| Ethical Status | Highly controversial due to embryo destruction | Generally accepted and widely used |
Therapeutic Introduction: Stem cell therapy involves the introduction of stem cells into damaged or diseased tissue to stimulate healing and functional recovery.
Disease Treatment: This method is used to treat conditions like leukaemia, where healthy bone marrow stem cells are introduced to replace cancerous ones.
Injury Management: Stem cells can be applied to treat physical injuries, such as severe skin burns, by accelerating the regeneration of the dermal and epidermal layers.
Research Frontiers: Scientists use stem cells to model diseases in a lab setting and to test the safety and efficacy of new drugs before human trials.
Identify Potency Levels: Always distinguish between 'pluripotent' and 'multipotent' in exam answers; using the wrong term can lead to a total loss of marks for that point.
Link Structure to Function: When asked about the significance of stem cells, always mention both unlimited division (mitosis) and differentiation.
Specific Examples: Memorize the bone marrow example as the standard illustration of multipotency; be prepared to list the specific blood cells it can produce.
Check the Context: If a question mentions 'adult' stem cells, ensure your answer reflects their limited range of differentiation compared to embryonic ones.
Misconception: All stem cells are the same: Students often forget that adult stem cells are restricted in what they can become; a skin stem cell cannot naturally become a neuron.
Confusion with Mitosis: While all stem cells divide by mitosis, not all cells that divide by mitosis are stem cells; specialized cells often lose the ability to divide entirely.
Potency vs. Totipotency: Avoid calling adult stem cells 'totipotent'; totipotency is reserved for the very earliest embryonic cells that can form an entire organism including the placenta.
