3. Stem cells II Flashcards
(22 cards)
What concept did John Gurdon’s nuclear transfer experiments challenge?
The concept that differentiation is unidirectional
Gurdon’s experiments demonstrated that differentiated cells could revert to a pluripotent state.
What was the process used in Gurdon’s nuclear transfer experiments?
- Took nucleus from differentiated skin cell of tadpole
- Destroyed nucleus of frog egg
- Transferred skin cell nucleus into enucleated egg
- Resulting egg developed into complete tadpole and adult frog
This process illustrated that differentiated cells retain complete genetic information.
What did Gurdon’s experiments reveal about differentiated cells?
Differentiated cells still contain complete genetic information
This finding was pivotal in understanding cellular reprogramming.
What is the significance of the egg cytoplasm according to Gurdon’s findings?
Contains factors that can reprogram a nucleus
This indicated that the developmental process might be reversible.
What did Gurdon’s work inspire in the field of cloning technology?
Later cloning technology, exemplified by Dolly the sheep in the 1990s
Gurdon’s findings laid the groundwork for advancements in cloning.
Who were the key figures in the development of induced pluripotent stem cells (iPSCs)?
Shinya Yamanaka and Kazutoshi Takahashi
Their work built on Gurdon’s nuclear transfer findings.
What are the four essential ‘Yamanaka factors’ for reprogramming cells?
- Oct4
- Sox2
- Klf4
- c-Myc
These factors are critical for maintaining pluripotency in stem cells.
What properties do iPSCs share with embryonic stem cells?
- Self-renewal
- Undifferentiated state
- Pluripotency
iPSCs can form all three germ layers and behave similarly to ESCs.
What was a significant application of iPSCs in disease modeling?
Microcephaly example using cerebral organoids
This application helped identify a mutation causing the disease.
What was the therapeutic application demonstrated by Rudolf Jaenisch’s lab for sickle cell anemia?
Reprogramming skin cells to iPSCs, correcting mutations, and transplanting back
This demonstrated a potential for personalized regenerative medicine.
What are the advantages of using iPSCs?
- Patient-specific (autologous)
- Avoid ethical concerns of embryo destruction
- Unlimited source of pluripotent cells
- Can model virtually any disease
- Potential for personalized medicine
iPSCs offer significant benefits over other stem cell types.
What are the limitations of iPSCs?
- Viral reprogramming can cause genomic instability
- Incomplete reprogramming
- Risk of teratoma formation
- Very expensive
- Efficiency issues (only ~1% successful)
- Regulatory challenges
These limitations pose challenges for clinical applications.
What are the two main types of niches for hematopoietic stem cells (HSCs)?
- Endosteal Niche
- Perivascular Niche
These niches provide different environments that affect HSC behavior.
What is the main clinical application of hematopoietic stem cells?
Hematopoietic Stem Cell Transplantation
This procedure is well-established for treating various blood disorders.
What are the advantages of adult stem cells?
- Natural cells with ‘memory’ of their environment
- Minimal cancer risk
- No ethical concerns
- Established clinical applications
- No genetic manipulation required
- Tissue-specific
Adult stem cells are advantageous for certain therapies.
What are the limitations of adult stem cells?
- Limited numbers in adult tissues
- Difficult to isolate and expand
- Limited differentiation potential
- Decreased function with aging
- Tissue-specific
These factors limit the use of adult stem cells in broader applications.
What is the source of embryonic stem cells?
Derived from the inner cell mass of a blastocyst
This source provides full pluripotency but raises ethical concerns.
How do iPSCs compare to embryonic stem cells in terms of ethical concerns?
Low ethical concerns (no embryo destruction required)
This makes iPSCs more favorable for research and therapy.
What is a significant risk associated with embryonic stem cells?
High potential for teratoma formation
This risk is due to the possibility of undifferentiated cells remaining.
What is the expandability of adult stem cells compared to iPSCs?
Limited expansion capacity in culture
This contrasts with the unlimited self-renewal capacity of iPSCs.
What is the main concern with the immunogenicity of embryonic stem cells?
Allogeneic with risk of immune rejection
This can complicate their clinical use.
What is the main takeaway regarding the choice of stem cell type?
Depends on specific research or clinical application
Each type has its advantages and limitations that influence their use.
