Lecture 3 Recording_Segment 2 Stem Cells_20240919_KGan

Note on Stem Cells and Organoids

Chapter 1: Introduction

  • Definition of Stem Cells

    • Unspecialized cells capable of giving rise to any cell type in the body.

    • Example: Fertilized egg as a master stem cell.

  • Properties of Stem Cells

    • Self-Renewal: Ability to make copies of themselves.

    • Differentiation: Can generate daughter cells with different structures and functions.

      • Asymmetric cell division: One stem cell divides into one identical and one differentiated daughter cell.

      • Symmetric division: Produces two identical stem cells or two differentiated cells, losing self-renewal capacity.

  • Stem Cell Niche

    • Microenvironment regulating self-renewal vs. differentiation.

    • Secretes signals influencing stem cell decisions.

  • Adult Stem Cells

    • Present in various organ systems, e.g., brain stem cells.

    • Limited potency compared to embryonic stem cells.

  • Potency Levels

    • Totipotent: Can form all cell types.

    • Pluripotent: Can form specific cell types from germ layers.

    • Multipotent: Limited to specific lineages (e.g., adult brain stem cells).

Chapter 2: Own Stem Cells

  • Precursor vs. Progenitor Cells

    • Progenitor cells arise from multipotent stem cells with limited self-renewal.

    • Precursor cells are more committed than progenitors.

  • Stem Cell Niche Mechanisms

    • Extracellular Mechanisms: Physical (cell adhesion) and chemical (secreted factors).

    • Intracellular Mechanisms: Internal cell processes, including protein distribution and gene expression.

Chapter 3: Different Embryonic Stem Cells

  • Isolation of Embryonic Stem Cells

    • Extracting stem cells from embryos at the blastocyst stage.

    • Culturing and inducing differentiation using morphogens (e.g., Wnts, FGFs).

  • Disease Modeling

    • Using induced pluripotent stem cells (iPSCs) to model diseases like sickle cell anemia.

    • Correcting mutations using CRISPR-Cas9.

Chapter 4: Pluripotent Stem Cells

  • Transplantation and Differentiation

    • Transplanting corrected stem cells back into models (e.g., mice).

    • Differentiating stem cells into affected cell types (e.g., blood cells).

  • Organoid Development

    • Creating 3D structures (organoids) to mimic organ formation.

    • Using morphogen cocktails to guide differentiation.

Chapter 5: Embryonic Stem Cells

  • Organoid Generation Protocol

    • Starting with human embryonic stem cells and exposing them to growth factors.

    • Embedding cells in 3D scaffolds for organoid development.

  • Applications of Organoids

    • Studying diseases without using human embryos.

    • Personalized medicine: Tailoring treatments based on patient-specific organoids.

Chapter 6: Conclusion

  • Mini Brain Development

    • Protocols for generating cerebral organoids.

    • Use of spinning bioreactors to maintain organoid viability.

  • Modeling Diseases

    • Organoids can model conditions like microcephaly due to Zika virus.

    • Observing changes in cell composition and layering in organoids.

  • Future Directions

    • Organoids provide a starting point for understanding brain development and disease.

    • Ongoing research needed to refine organoid technology and