Why do we need to have stem cells?
To regenerate tissues and systems
Who propose the origin of the stem cell?
What did he show?
Ernst Haeckel in 1868
Showed:
- There was a commonality of the origin of the species and how species branch out through evolution
What is a Stammbaum?
Who proposed this model?
The tree of life:
- With many different branches
Proposed by Ernst Hackel
What did Boveri propose in 1892?
That stem cells are not the only initial cells but also those of between the fertilised egg and the committed germ cell
What did Hacker do in 1892?
Applied stem cells to the cyclops embryo undergoing asymmetric division
What did Pappenheim do in 1905?
What does the word ‘stem cell’ describe?
A wider and wider range of cell types, all with similar underlying concepts (that the cells produce different lineages and progenies)
What is a stem cell?
A cell that has the potential to generate different specialised cell types/tissues (DIFFERENTIATION)
As well as copies of themselves (SELF-REPLICATION)
What are the 3 ways of classifying stem cells?
1) Age of development
2) Tissue of origin
3) Potential to produce different cell types (functional capacity)
4) Therapeutic potential
How are stem cells classified by the age of development?
1) Embryonic
2) Adult
Where are embryonic stem cells taken from?
The very early stage embryo (blastocyst stage)
Where are adult stem cells taken from?
The SOMATIC and FOETAL tissues
How are stem cells classified by their tissue of origin?
Where taken from, eg:
- Neural stem cells (from neural tube)
How are stem cells classified by their functional capactiy?
Capacity to produce other lineages:
1) TOTIPOTENT
2) PLURIPOTENT
3) MULTIPOTENT
4) UNIPOTENT
What are TOTIPOTENT stem cells?
Give an example of these cells
Cells that can give rise to ALL of the cells of the human body, including the trophoblast (extra-embryonic tissues)
Eg. Cells of the fertilised zygote
What are PLURIPOTENT stem cells?
Give an example of these cells
Cells that can produce the derivatives from all 3 of the germ layers: ectoderm, endoderm and mesoderm
Eg. ES cells (embryonic stem cells)
What are MULTIPOTENT stem cells?
Give an example of these cells
TISSUE SPECIFIC stem cells (give rise to different cell types from a specific tissue or organ)
Can produce different lineages but of a reduced number (normally related to that proliferative organ/tissue)
Eg. neural stem cells - give rise to neurons, astrocytes, Schwann cells
What are UNIPOTENT stem cells?
Give an example of these cells
Cells that produce a single cell type
Eg. Muscle satellite cells
What is the trophoblast?
Gives rise to the placenta
How do stem cells usually behave in a tissue?
They normally replicate (self-renew) slowly
How are cells kept in their slow, self-renewing stage in the tissue?
By the niche:
Cells in the niche secrete factors that contribute along with the extracellular matrix to keep the cells quiescent
What happens to the stem cells when they are needed to divide?
They are triggered to divide RAPIDLY:
- Cells become progenitors (transit amplifying cells)
What are the 3 different therapeutic potentials for stem cells?
1) ALLOGENIC treatment
2) AUTOLOGOUS treatment
3) RECRUITMENT
What is ALLOGENIC treatment with stem cells?
Examples?
Stem cells are derived from a DONOR, expanded in a dish and used to treat a larger population of patients (outside of the initial person)
Eg. ES cells, cord blood cells