Stem Cells and Neurogenesis Flashcards
Define the properties of stem cells Describe the similarities and differences between pluripotent and tissue-specific stem cells Discuss the importance of pluripotent cells in neuroscience Define the properties and localisation of neural stem cells in the CNS Discuss how neural stem cells are temporally and spatially regulated during development
What are stem cells?
Unspecified cells which can either differentiate into specialised cell types or self-renew - divide to create two daughter cells, at least one of which is equivalent to the parent cell
Define totipotency, and give an example
The ability of a cell to form an entire organism
Example: zygote
Define pluripotency
The ability of a cell to form all the body’s cell lineages, including germ cells, but which cannot form an entire organism due to an inability to generate the placenta
Define multipotency
The ability of a cell to form multiple cell types, constituting an entire tissue or tissues, but only in one cell lineage
Name the three embryonic germ cell layers
Ectoderm, mesoderm, and endoderm
Which lineage forms neural lineages and skin cells?
Ectoderm
Which germ cell lineage forms bone, muscle, and blood cells?
Mesoderm
Describe the stages after a sperm has fertilised an egg
This forms a zygote, which then becomes a blastocyst. The blastocyst undergoes implantation, then gastrulation, before differentiating into the ectoderm, mesoderm, endoderm, and germ cells
Which four transcription factors are given to human cells to turn them into induced pluripotent stem cells?
Oct4, Sox2, Klf4, and c-Myc
How are embryonic stem cells obtained?
They are isolated from the inner cell mass of the pre-implantation blastocyst and cultured
Which intrinsic transcription factors maintain pluripotency in stem cells?
Oct4, Sox2, and Nanog
How is pluripotency assessed?
Pluripotent stem cells are aggregated in a culture disc to form embryoid bodies, then plated to detect the three different differentiation markers - AFP for endoderm, mActin for mesoderm, and beta-TubIII for ectoderm
How are mouse pluripotent stem cells assessed?
Chimera formation. Pluripotent stem cells are injected into a blastocyst from a different strain of mouse, then transplanted into a mouse of the same strain as the original mouse to act as a surrogate mother. The resultant offspring should have the characteristics of both mice down to their germ cells
Where are haematopoeitic stem cells found?
Short-term cells are found close to blood capillaries, and long-term cells close to the osteoblasts
Where are intestinal stem cells found?
The bottom of intestinal crypts
How are somatic stem cells different to pluripotent stem cells?
They have limited, niche-dependent self-renewal capacity, and cannot form teratomas as they lack sufficient plasticity. They also exist in vivo and exhibit limited growth in vitro, whereas pluripotent stem cells do not exist in vivo
What is a stem cell niche?
The microenvironment which surrounds and nurtures the stem cells, enabling them to maintain tissue homeostasis
Which develops first in culture of neural cells, neurons or glia?
Neurons
What are the advantages of somatic stem cells for cell therapy?
Autologous so low rejection risk, low risk of tumour growth, few ethical issues
What are the disadvantages of somatic stem cells for cell therapy?
Limited growth and accessibility, limited differentiation potency
What are the advantages of pluripotent stem cells for cell therapy?
Can be expanded to a large number of cells, capable of generating all cell types
What are the challenges of pluripotent stem cell use in cell therapy?
Not all control signals for differentiation are understood, integration and survival, tumourigenesis, ethical issues of embryonic stem cells, immune rejection of embryonic stem cells
At what stage are pluripotent stem cells for neurogenesis currently transplanted?
As neural progenitors
