stem cell Flashcards
what are stem cells?
they can:
Self-renew and differentiate into all cells of a particular lineage or tissue
Embryonic development
- sperm and egg - zygote stage
- split into 2,4
3.morula
4.blastocyst - used to make embryonic stem cells
During granulation, what are the three germ layers formed?
During gastrulation, get the three germ layers:
Ectoderm
Mesoderm
Endoderm
These will give rise to all cell types of the body
what are the different types of stem cell potency?
Totipotent cells can give rise to ANY cell type
Pluripotent stem cells (PSCs) can give rise to any cell of the body (ESCs)
Multipotent stem cells can rise to any cell of a specific lineage/tissue (tissue-specific, adult stem cells)
what is cellular differentiation?
Cellular differentiation is when a cell goes from a less specialised to a more specialised state
how can you drive differentiation of stem cells in vitro?
Use knowledge of developmental biology: Developmental Approach
Or can take a more Empirical approach
what is the sources of stem cells?
- Pluripotent-derived sources of cells (ESC) –> multipotent stem cells –> all cell types of the body including brain, liver, heart, blood etc
-ethics of where they are derived from
2.Adult-derived / tissue-specific stem cells: sources
bone marrow - ( 2 different stem cells - HSCs and MSCs) –> blood –> can generate Bone (osteoblasts), muscle (myocytes), fat (adipocytes), cartilage (chondrocytes) –> Studies have used these and other cells (e.g. in vitro cell lines)
- dental pulp, urine, umbilical cord - sources of stem cells
for the nervous system, there is no ready source for the body - this is where pluripotent is useful as this can be made.
what is Cell Reprogramming: ESCs
ESCs typically from unused IVF embryos – ethical and technical limitations - embryos are destroyed at the end
Take enucleated egg and a somatic cell
which generates Somatic cell nuclear transfer (SCNT)
which develops the embroyo
which makes pluripotent
carry the genome of the donor - therefore organism specific
Cell reprogramming: iPSCs and its ethical implications
whats the benefits?
No need to generate an embryo, used mouse fibroblasts
Less ethical implications and major advantages for disease research - dont need to destroy.
Human iPSCs (hiPSCs) can be created from any individual
hiPSCs have genetics of that individual
Can create patient-specific hiPSCs
Can create disease-specific hiPSCs (e.g. carrying specific mutations)
Modern gene editing allows correction of mutations or specific genetic modification (e.g. CRISPR-Cas9, can manufacture ‘disease’ lines or correction of mutations to make isogenic controls)
difference between ESCs and IPSC?
For regenerative medicine, both have risks of tumorigenicity (due to pluripotent nature)
ESCs limited in availability and versatility – cannot be patient specific
More ethical issues surrounding ESCs
iPSCs – possibility of personalized medicine
iPSCs for disease-specific modelling
Both can be differentiated into any body cell type
Questions on safety of iPSCs from e.g. mutation or reprogramming methods > improving
what are the uses of stem cells for research?
Developmental Biology & basic research
Understanding disease & drug discovery
Cell-based therapy
Stem Cells in RegenerativeMedicine - HSCs
Stem cell/bone marrow transplants
HSCs: to treat cancers of blood/bone marrow e.g. leukemia, myeloma, lymphoma and non-cancer disorders such as sickle-cell anaemia
Stem Cells in modelling disease
There has been extensive use of Stem Cells in modelling disease and drug discovery and testing
