8.2.3 The Use of Stem Cells

Types of Stem Cells

Stem cells are categorised based on their ability to differentiate into specialised cell types:

1. Totipotent Stem Cells:

• Can differentiate into any type of cell in the body, including extra-embryonic cells (e.g., placenta).
• Found in the early stages of the zygote.

2. Pluripotent Stem Cells:

• Can form any cell type in the body but cannot form extra-embryonic cells.
• Found in the early embryo.
• Commonly used in regenerative medicine to replace damaged tissues.

3. Multipotent Stem Cells:

• Can differentiate into a limited range of cell types.
• Example: Found in bone marrow and umbilical cord, producing blood cells.

4. Unipotent Stem Cells:

• Can differentiate into only one type of cell.
• Example: Skin stem cells regenerating skin.

Pluripotent Stem Cells in Medicine

Pluripotent stem cells are used in the treatment and repair of damaged tissues, such as:

• Spinal cord injuries: Promoting regeneration of damaged nerve cells.
• Heart disease: Repairing heart muscle tissue after a heart attack.
• Type 1 diabetes: Replacing insulin-producing cells in the pancreas.
• Burn treatment: Regrowing damaged skin using stem cell-based grafts.
• Neurodegenerative diseases: Replacing lost or damaged neurons in conditions like Parkinson's disease.

Induced Pluripotent Stem Cells (iPS)

• iPS cells are artificially created pluripotent cells generated from unipotent cells (e.g., skin cells).
• This process involves reprogramming genes to make the unipotent cells behave like pluripotent stem cells.
• Advantages of iPS cells:
  • Avoids ethical concerns surrounding embryonic stem cells.
  • Can be derived from the patient's own cells, reducing the risk of rejection.

Ethical Issues and Challenges

• Use of embryonic stem cells raises ethical concerns due to the destruction of embryos.
• iPS cells offer a more ethically acceptable alternative but are still under research to ensure their safety and efficacy.