Stem Cells basics and niche Flashcards
What are the circumstances that you would find asymmetric or symmetric stem cells?
Asymmetric self-renewal- cells associated with tissues
Symmetric self-renewal- transient stem cells involved in early development
Briefly summarise the the different regulation of stem cells
Extrinsic- neighbouring cells, orientation, morphogens, growth factors, cytokines
Intrinsic- growth factor and cytokines receptors, transcriptional regulators, signal pathway, cell survival
What is meant by totipotent?
The zygote is totipotent up to the 8 cell stage, it has the potential to give rise to any and Al human cells
What is meant by pluripotent?
They can give rise to all tissue types, ie. the embryo proper
They cannot give rise to extra-embryonic structures- trophectoderm
What is meant by mutipotent?
They give rise to a limited range of cells within a tissue type
Their daughter cells become the progenitors of cell lines
What ability must a stem cell have to be classified as pluripotent?
The ability to give rise to the three germ layers- endoderm (eg. Neurones of the brain), mesoderm (eg. Red blood cell) and ectoderm (eg. Pancreatic cell)
What stain would you use to test for pluripotency in vitro?
Is it positive for alkaline phosphatase
What would you plate stem cells with do that they keep their pluripotency?
Irritated feeder layer Up to day 13 mouse embryo Remove heads and internal organs Treat with trypsin and plate cells into a dish They form embryonic fibroblasts They're irradiated to stop growth
What would pluripotent stems show grown in vitro and in vivo?
In vitro- Differentiation is triggered when frien in suspension and embryoid bodies form
In vivo- teratoma formed when injected into a nude mouse
How is stem cell division different from normal cell division?
Normal cell division gives rise to two non-identical daughter cells of the same type
Stem cell division gives rise to one use identical daughter cell in asymmetric division and two identical daughter cells in symmetric division
What in the niche signals to the stem cell to differentiate?
The niche cells and the ECM influence what type of cell is produced- secreted or cell surface factors control cell renewal, maintenance and survival
The micro environment is important to the differentiation profile of the SC
When a cell is not differentiating it is said to be in…?
Quiescence
What proteins are important in Stem cell differentiation in the niche?
Mof proteins
Cyclin Ds
Lamins
What are some physiochemical factors found in the stem cell microenvironment that affect it?
pH
Oxygen tension
Ionic strength (Ca in particular)
Metabolites and ATP
What is the ‘holy trinity’ of factors that control stem cell differentiation?
Oct4
Sox2
Nanog
