Stem Cells and Viruses Lecture

Overview

Topics Covered: Stem Cells (Ch. 19 - Highlights from 19.3 and 19.4), Viruses (Ch. 26 - Highlights from 26.1 and 26.4)

Zygote Formation: Formed by fertilization between sperm and egg. A diploid cell (2N).
Cleavage: Initial development process, mitosis creating identical daughter cells.
Blastocyst Stage: Important stage containing embryonic stem cells (implanted in IVF).
Embryonic Stem Cells: Derived from the inner cell mass (embryoblast) of the blastocyst.

Totipotent: Can give rise to any tissue in an organism (~Morula stage).
Pluripotent: Can give rise to all cell types in the body (embryonic stem cells).
Multipotent: Can give rise to a limited number of cell types (e.g., stem cells in bone marrow).
Unipotent: Can give rise to only one cell type (e.g., epidermal stem cells).

Potential Therapies:
- Diabetes: Grow new healthy pancreatic islet cells to produce insulin.
- Anemia: Produce healthy hemoglobin and red blood cells.
- Heart Disease: Grow healthy heart muscle cells; successful surgeries (e.g., in Italy).
- Neuronal Diseases: Grow new neurons for spinal cord injuries, neurodegenerative diseases.
- Liver Disease: Grow healthy liver cells.
- Eye Disorders: Experiments with retinal therapies.

Ethical Issues: Using embryos that cannot develop into babies.
Alternative Methods:
- Reprogramming Adult Cells: To become pluripotent without using embryos.
- Somatic Cell Fusion: Fusing adult cells to embryonic stem cells.
- Gene Introduction: Introducing genes to induce pluripotent cells (e.g., in skin cells).
- Culturing Germ/Adult Stem Cells: To create pluripotent cells.

Less Rejection: If cells are derived from the patient, reducing the risk of rejection.
Applications: Use in diseases like diabetes and generating specific tissues for therapy.
Somatic Cell Nuclear Transfer (SCNT): Cloning technique, used to create Dolly the sheep.

Dolly the Sheep: First mammal cloned from an adult cell (1996).
- Process: Adult cell nucleus inserted into egg cell (without its nucleus), triggered development.
- Results: Dolly was fertile, gave birth to offspring, lived about half-lifespan due to possible telomere shortening.
Challenges: Low efficiency, complications in clones, aging issues, genomic imprinting concerns.
Current Uses: Cloning pets like dogs and horses.

Key Topics:
- Cleavage process from zygote to morula to blastocyst.
- Different types of stem cells and their properties.
- Application and challenges of using embryonic stem cells.
- Differences between reproductive and therapeutic cloning.