1. Definition
Stem cells are unique cells in the body that have the ability to develop into many different cell types. They can divide and renew themselves for long periods and differentiate into specialized cells.
2. Types of Stem Cells
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Embryonic Stem Cells:
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Derived from early-stage embryos (blastocysts).
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Pluripotent — can become almost any cell type in the body.
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Adult (Somatic) Stem Cells:
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Found in various tissues (e.g., bone marrow, skin).
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Multipotent — limited ability to become a few related cell types.
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Induced Pluripotent Stem Cells (iPSCs):
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Adult cells genetically reprogrammed to behave like embryonic stem cells.
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Pluripotent and used for research and therapy.
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3. Characteristics
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Self-renewal: Can divide and produce more stem cells.
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Potency: Ability to differentiate into specialized cell types (totipotent, pluripotent, multipotent).
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Undifferentiated: Do not have specific tissue functions until they differentiate.
4. Functions and Importance
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Development: Essential in early embryo development.
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Tissue Repair: Help regenerate damaged tissues by producing new cells.
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Research and Medicine: Used to study diseases, develop drugs, and in regenerative therapies.
5. Medical Applications
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Regenerative medicine: Treating diseases by replacing damaged cells (e.g., leukemia treatment with bone marrow transplants).
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Tissue engineering: Growing organs and tissues in the lab.
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Drug testing: Testing new drugs on cultured stem cells.
6. Ethical Considerations
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Use of embryonic stem cells raises ethical debates because it involves the destruction of embryos.
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Research increasingly focuses on adult and induced pluripotent stem cells to avoid ethical issues.
7. Current Challenges
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Controlling differentiation precisely.
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Avoiding immune rejection after transplantation.
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Ensuring safety and effectiveness in therapies.