Pluripotent Stem Cells Lecture Notes

Flashcards based on the lecture notes covering pluripotent stem cells, iPSCs, ESCs, and related concepts.

What is cell reprogramming?

Cell reprogramming is the process of altering the differentiation state of a cell, typically to revert a specialized cell to a pluripotent or less differentiated state.

Describe the role of Oct4 in maintaining pluripotency.

Oct4 is a transcription factor crucial for maintaining pluripotency and self-renewal in embryonic stem cells. It regulates the expression of genes involved in these processes and prevents differentiation.

How do iPSCs overcome ethical issues associated with ESCs?

iPSCs bypass the ethical concerns related to the destruction of embryos because they are derived from adult somatic cells, which are reprogrammed to an ESC-like state.

What are the limitations of using iPSCs in therapies?

Limitations of iPSCs in therapies include the risk of incomplete reprogramming, potential for tumorigenicity due to c-Myc, and the necessity for viral vectors for factor delivery, which can cause insertional mutagenesis.

How does the Wnt signaling pathway promote self-renewal?

The Wnt signaling pathway promotes self-renewal by stabilizing β-catenin, which then translocates to the nucleus and activates transcription factors that drive cell proliferation and pluripotency.

Explain the significance of feeder layers in ESC culture.

Feeder layers, typically composed of irradiated or mitotically inactivated fibroblasts, provide essential growth factors and extracellular matrix components that support ESC survival and self-renewal in culture.

What is the role of Activin/Nodal signaling in ESCs?

Activin/Nodal signaling is essential for maintaining pluripotency in human ESCs. It activates SMAD2/3, which regulates the expression of genes critical for self-renewal and inhibiting differentiation.

Describe the process of somatic cell nuclear transfer (SCNT).

Somatic cell nuclear transfer (SCNT) involves transplanting the nucleus of a somatic cell into an enucleated oocyte to create a cloned embryo, from which ESCs can be derived.

How do epigenetic modifications affect pluripotency?

Epigenetic modifications, such as DNA methylation and histone modification, play a crucial role in regulating gene expression patterns that support pluripotency and prevent differentiation in ESCs.

What are the advantages of using CRISPR technology in stem cell research?

CRISPR technology allows for precise gene editing in stem cells, facilitating the study of gene function, disease modeling, and the development of targeted cell therapies.

What is the defining characteristic of a stem cell?

The defining characteristics of a stem cell are the ability to self-renew (divide and create more stem cells), be clonal (derived from a single cell), and differentiate (develop into specialized cell types).

What are the two main types of pluripotent stem cells?

The two main types of pluripotent stem cells are Embryonic Stem Cells (ESCs), derived from the inner cell mass of a blastocyst, and Induced Pluripotent Stem Cells (iPSCs), which are generated from differentiated cells through reprogramming.

Define Totipotent

Totipotent cells have the capacity to form all tissues, including the placenta, enabling the development of a complete organism. An example is a fertilized egg (zygote) or the cells of the very early embryo.

Define Pluripotent

Pluripotent cells can differentiate into all cells of the embryo/adult body, but cannot form the placenta. Embryonic Stem Cells (ESCs) are a prime example of pluripotent cells.

What is needed to maintain pluripotency during ESC self-renewal?

Maintaining pluripotency during ESC self-renewal requires the promotion of proliferation and suppression of differentiation. This is achieved via Extrinsic signals (e.g., growth factors), Signalling pathways (e.g., JAK/STAT), and Intrinsic factors (e.g., transcription factors).

What is LIF and its role in stem cell maintenance?

Leukaemia Inhibitory Factor (LIF) is a cytokine that maintains self-renewal in mouse ESCs by activating the JAK/STAT3 pathway, which promotes cell proliferation and inhibits differentiation.

How does BMP4 prevent differentiation?

BMP4 (Bone Morphogenetic Protein 4) prevents differentiation by activating SMAD proteins, which upregulate ID (Inhibitor of Differentiation) genes. ID proteins then inhibit the activity of differentiation-promoting transcription factors.