Biology Module 41: Stem Cell Types and Differentiation

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Questions and Answers

What is a critical factor that allows patient-derived adult stem cells to be advantageous in therapies?

They eliminate the issue of immune rejection. (correct)

They have higher potency than embryonic stem cells.

They require less extensive ethical approval.

They can be transformed into any cell type.

Which type of stem cell is associated with significant ethical and moral debates?

Bone marrow stem cells

Embryonic stem cells (correct)

Adult stem cells

Induced pluripotent stem (iPS) cells

What does EMT (Epithelial-Mesenchymal Transition) make cells more capable of during cancer progression?

Becoming more mesenchymal and invasive. (correct)

Regenerating normal tissue.

Being non-invasive and proliferative.

Differentiating into epithelial tissue.

What is a methodological challenge in stem cell therapies mentioned in the content?

Creating safe and effective delivery systems. Signup and view all the answers

During which process do cancer cells return to an epithelial phenotype?

Mesenchymal-Epithelial Transition (MET) Signup and view all the answers

What is a risk associated with the use of adult stem cells?

They have limited potency compared to iPS cells. Signup and view all the answers

What is the primary aim of successful stem cell therapy?

To regenerate damaged tissues. Signup and view all the answers

What factors drive the process of EMT in cancer cells?

ZEB transcription factors and SLUG. Signup and view all the answers

What characterizes senescent cells?

They are larger and remain metabolically active. Signup and view all the answers

What type of stem cells can form a new individual?

Totipotent stem cells Signup and view all the answers

Which of the following is a pathway that can activate caspase 9?

The intrinsic pathway Signup and view all the answers

What is the primary function of executioner caspases during apoptosis?

To degrade cellular macromolecules. Signup and view all the answers

Which stem cell type is capable of forming any of over 200 different cell types?

Pluripotent stem cells Signup and view all the answers

What is the primary role of Notch signaling in intestinal cell differentiation?

Regulates lateral inhibition for cell fate determination Signup and view all the answers

How does Bax facilitate apoptosis?

By facilitating the release of cytochrome c from mitochondria. Signup and view all the answers

Which of the following best describes dedifferentiation in the context of adult stem cells?

The reversion of progenitor cells to a less differentiated state Signup and view all the answers

Which feature distinguishes apoptosis from necrosis?

Apoptosis leads to cell fragmentation and blebbing. Signup and view all the answers

How does BMP signal influence stem cell differentiation in the intestinal crypt?

Increases at the top of the crypt and promotes differentiation Signup and view all the answers

What role do Bcl-2 family proteins play in apoptosis?

They regulate apoptosis through mitochondrial-mediated pathways. Signup and view all the answers

What characterizes multipotent stem cells compared to higher potency stem cells?

They can differentiate into several tissue types Signup and view all the answers

What happens during the early stages of apoptosis?

The membrane starts to bleb. Signup and view all the answers

Which cell characteristics are reinforced in Notch-high, Dll-low cells during differentiation?

Increased absorptive cell lineage commitment Signup and view all the answers

What is the consequence of deregulated apoptosis?

It contributes to various diseases including cancer. Signup and view all the answers

Which type of cell is considered a progenitor cell?

A cell that has begun the differentiation process Signup and view all the answers

What effect does enhanced Wnt signaling have on cancer cells during EMT?

It increases invasiveness and reduces proliferation. Signup and view all the answers

What limitation is associated with adult stem cells in therapeutic applications?

They have limited potency and versatility. Signup and view all the answers

Which process allows cancer cells to revert to an epithelial state and potentially form metastatic tumors?

Mesenchymal-Epithelial Transition (MET) Signup and view all the answers

What major challenge needs to be addressed for induced pluripotent stem (iPS) cells to be used safely in therapies?

Ensuring their effectiveness and safety. Signup and view all the answers

What is one of the key advantages of using patient-derived adult stem cells?

They eliminate the risk of immune rejection. Signup and view all the answers

How do differentiation enhancers influence intestinal stem cells?

They activate genes for secretory and absorptive lineages. Signup and view all the answers

Which of the following statements about EMT is true?

EMT is driven by various signaling factors including Wnt and ZEB. Signup and view all the answers

What characterizes the phenotype of cells undergoing EMT?

They become non-proliferative and invasive. Signup and view all the answers

What is the function of enhancers associated with stemness in differentiated cells?

They are turned off to support differentiation.</ Signup and view all the answers

What are some risks associated with adult stem cell use in therapies?

There is a high likelihood of the development of cancer. Signup and view all the answers

What is the primary characteristic of totipotent stem cells?

They can form any cell type, including the placenta. Signup and view all the answers

Which of the following stem cell types is primarily responsible for forming multiple tissues but is somewhat differentiated?

Multipotent stem cells Signup and view all the answers

In the context of cell differentiation, what role does Notch signaling primarily serve?

It regulates cell fate decisions via lateral inhibition. Signup and view all the answers

Which signaling pathway is associated with promoting stem cell self-renewal in the intestinal crypt?

Wnt signaling Signup and view all the answers

What is meant by dedifferentiation in stem cell biology?

A progenitor cell loses its differentiation and regains stemness. Signup and view all the answers

Which factor contributes to the promotion of differentiation in Notch-low cells?

Increased Atoh1 expression Signup and view all the answers

What is a characteristic difference between higher potency and lower potency stem cells?

Higher potency stem cells have greater differentiation potential. Signup and view all the answers

What is the role of BMP signals in the intestinal crypt?

Facilitate differentiation of stem cells. Signup and view all the answers

What occurs when progenitor cells transition to a mature cell?

They become more differentiated. Signup and view all the answers

Which signal is higher at the bottom of the crypt and is associated with stem cell self-renewal?

Wnt signaling Signup and view all the answers

What defines the characteristics of senescent cells?

They are unable to divide but remain metabolically active. Signup and view all the answers

Which protein promotes apoptosis by facilitating the release of cytochrome c?

Bax Signup and view all the answers

What is primarily released from the mitochondria to activate the intrinsic pathway of apoptosis?

Cytochrome c Signup and view all the answers

What is a key morphological change observed during apoptosis?

Membrane blebbing Signup and view all the answers

Which of the following statements about necrosis is true?

It is typically triggered by external factors. Signup and view all the answers

Deregulated apoptosis can contribute to which of the following outcomes?

Excessive cell death or insufficient cell death Signup and view all the answers

What is the role of executioner caspases during apoptosis?

To degrade cellular macromolecules Signup and view all the answers

Which of the following is a characteristic feature of apoptotic cells?

Nuclear fragmentation Signup and view all the answers

What ultimately results from increased numbers of senescent cells with age?

Contribution to age-related diseases Signup and view all the answers

What distinguishes Bcl-2 family proteins in the regulation of apoptosis?

They can be either pro-apoptotic or anti-apoptotic. Signup and view all the answers

Study Notes

Module 41

Stem Cell Types:
- Totipotent: forms a new individual (early human embryo, 1-3 days).
- Pluripotent: forms any of over 200 cell types (embryonic stem cells, some human blastocyst cells, 5-14 days).
- Multipotent: differentiates into several tissues (fetal tissue, cord blood stem cells, adult stem cells).
Stem Cell Differentiation:
- Stem cell (A) → Progenitor cell (B) → Differentiated cell (C).
- Differentiation: a cell's change in specialization.
- Professional stem cells: permanent, example: Lg5+ CBC cells in the intestine.
- Dedifferentiation: a progenitor cell becoming less differentiated, gaining stemness, and returning to a multipotent stem cell state.
- Stem Cell Regulation:
  - Constant cell signaling:
    - Wnt signalling & Bmp antagonists (higher at bottom of crypt, regulating self-renewal)
    - BMP, Hedgehog, and Hippo signalling (increase going up crypt, promoting differentiation)
    - Notch signaling (controls cell differentiation via lateral inhibition).
  - Cell potency: High potency stem cells can differentiate into more cell types than low potency stem cells.
Notch Signaling and Cell Fate:
- Notch-Dll interactions affect cell signalling in each cell.
- Notch-high cells:
  - Increased expression of HES1 and decreased expression of Atoh1 and Dll promotes differentiation into the absorptive cell lineage.
- Notch-low cells:
  - Decreased expression of HES1 and increased expression of Atoh1, which promotes higher Dll expression, promoting differentiation to secretory cell lineage.
- Notch signalling is crucial in lateral cell inhibition.

Module 42

Stem Cell Challenges:
- Safe and effective delivery systems for stem cell therapies.
- Ethical and moral debates surrounding embryonic stem cells.
- Further research on induced pluripotent stem (iPS) cells for therapeutic use.
- Immune rejection when using donor cells (not an issue with cells from patients).
- Limited potency of adult stem cells; risk of mutations and increased likelihood of cancer development
Stem Cell Treatments and Advantages:
- Patient-derived cells eliminate immune rejection, important for personalized therapies
- Bone marrow transplantation.
- Regenerating damaged tissues (not a permanent cure).
Epithelial-Mesenchymal Transition (EMT) and Mesenchymal-Epithelial Transition (MET):
- EMT (embryogenesis): cancer cells potentially become mesenchymal, invasive, and non-proliferative, allowing metastasis.
- MET (embryogenesis): cancer cells at distant organs & tissues, become epithelial, proliferate to form metastatic tumors.

Module 44

Senescent Cells:
- Defined by their inability to divide but remaining metabolically active.
- Increased division is not a cause, but results from cellular stressors (telomere shortening, oxidative damage).
- Larger and metabolically active unlike apoptotic cells.
- Increased number with age is linked to age-related diseases.
Apoptosis Pathway:
- Cell death pathway: includes nuclear fragmentation, chromatin condensation.
- Caspase 9 in the intrinsic pathway
- Caspase-independent pathways.
Apoptosis Regulation: Excessive/insufficient cell death can contribute to diseases (e.g., cancer).
Other Apoptosis Details:
- Executioner caspases: degrade cellular macromolecules
- Bcl-2 family proteins: pro- and anti-apoptotic, regulating apoptosis.
- Membrane blebbing: early stage of programmed cell death.
- Bax protein: pro-apoptotic (releases cytochrome C); Bcl2, Bcl-xL: anti-apoptotic.
- Nuclear Fragmentation (characteristic of apoptosis)
- Necrosis: triggered by external factors (infections, toxins, trauma, etc.) leading to cell damage.

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Description

This quiz covers the various types of stem cells, including totipotent, pluripotent, and multipotent cells. It also delves into the processes of stem cell differentiation, dedifferentiation, and the regulatory mechanisms involved in these processes. Test your understanding of stem cell biology and their potential applications.