Stem Cells Flashcards
What is a stem cell?
A stem cell is a primitive cell that gives rise to a [differentiated, specialized daughter cell] and
self-renews into a more
[stem cells]
T/F: Stem cells can functionally reconstitute a given tissue in vivo.
T.
Are stem cells terminally differentiated
no, they are not terminally differentiated
How often can stem cells divide? and how fast
They have telomerase; they can divide without limit. However, they undergo a slow division.
Which stem cells are tissue specific?
Adult stem cells are tissue specific.
Ex. A stem cell in the liver will only produce liver cells.
The proliferative potential of a stem cell is called ________
potency
3 types of proliferative potential
- Totipotency
- Pluripotency
- Multipotency
Totipotency
Type of stem cell:
Location:
the ability for a single cell to give rise to all kinds of organisms, including embroyonic and extraembroyonic tissue.
Type: embryonic stem cell
Location: totipotent cells are located in the zygote
Pluripotent
Type of stem cell:
Location:
Pluripotent can give rise to all cells of the embryo and adult tissues.
Type of stem cell: embryonic stem cell
Location: Pluripotent cells are located in the blastocyte
Mulitpotent
Type of stem cell:
Location:
Multipotent cells can only give rise to any cell in a SPECIFIC lineage.
Type of stem cell: Adult stem cells
Location: Multipotent cells are located in various tissues
Pluripotent stem cells can be isolated from:
the inner cell mass of a blastocyte 7 cultured into an embroyonic stem cell , which can make any cell type
Can multipotent stem cells give rise to all cells?
NO.
The can only give rise to cells in a specific tissues
_________ stem cells has increased potential for therapeutics
Pluripotent
Founder stem cells
Founder cells are constantly present in organs and have a fixed number. Founder stem cells determine the size of an organ via signaling. Thus, they have a finite number of division.
Transit Amplifying Cells
Transmit amplifying cell is not a stem cell.
Transit amplifying cell has differentiated from a stem cell.
Transit amplifying cell is formed when a stem cell replicated: forms another stem cell and a transitt amplifying cell.
it has a finite number of divisions
What is the difference between stem cells and transit amplifying cell?
- TACs are not stem cells, they’re more differentiated and are pushed to become the target cell. Stem cells, on the other hand, are undifferentiated
- Stem cells can divide an unlimited number of times
Transit amplifying cells have a limited number of divisions.
What is the purpose of transit amplifying cells?
growth control
Are transit amplifying cells committed?
Yes. they are more specific and will become a cell of a certain lineage.
To have a steady pool of stem cells, what happens?
To have a steady pool, 50% of our daughter cells must remain as stem cells and retain original DNA.
the other 50% can differentiate.
What processes occur to create a steady pool of stem cells?
- Divisional asymmetry
2. Environmental asymmetry
Divisional asymmetry
The asymmetric division of a stem cell produces
- a stem cell with the same DNA
- A cell that has the ability to differentiate
Environmental asymmetry
Division of a stem cell makes 2 identical cells, but 1 is influenced by the environment
Immortal strand hypothesis
Proposes that adult stem cells retain their DNA information to reduce genetic errors.
Original strand of DNA is preserved in the stem cell from generation to generation
Second cell gets the newly made strand
adult stem cells are ________
multipotent
Embryonic stem cells are _______
totipotent
and pluripotent
Embryonic stem cells
- derived from the blastocyst stage of a embryo
- can proliferate indefinitely.
- When put back into the blastocyst, they can integrate well with the embryo. However, if they are put back in a later stage, they fail to receive appropriate cues to differentiate properly.
Bad thing about embryonic stem cells
Can become a TERTOMA, which have a number of different tissue
Genes in pluripotent cells
Research has found that there are genes expressed only in pluripotent cell populations. These include
Transcription factors: 1. Nanog 2. Oct4 3. Sox2 4. FoxD3 which are necessary for establishment and maintenance of pluripotent stem cells.
& growth factors such as Cripto and GDF3
growth factors in pluripotent cells
Cripto
GDF3
What can we interpret about gene expression in pluripotent stem cells?
There is a common molecular blueprint of gene expression
Adult stem cells
- Found in tissue
- Respond to the demands of growth/repair.
-gene expression is STRICTLY maintained but can be altered by the environemtn .
Do we see terotomas in adult stem cells?
No, they have restricted capacity and growth potential.
& because they retain properties of the original tissue and have memory of its developmental hx.
In bone marrow, we have 2 types of adult stem cells:
- Hematopoietic
2. Stromal stem cells
Hematopoietic stem cells
come from bone marrow
can differentiate into blood components (RBC, WBC, platelets
Mesenchymal stem cells can become
connective tissues and tissues
Cord blood
Undifferentiated and does not require gene manipulation.
But ethical barriers?
Mesenchymal stem cells are a type of _______, stromal stem cell
multipotent stromal stem cell
What are the central strategies for regenerative medicine?
- Reprogram primary cells into the desired cell type
2. Use pluripotent cells
________ is a serious problem in adult stem cells
immune rejection
Inductively pluripotent stem cells: IPS
Reprogram an adult cell back into a pluripotent
Done by transcription factors
Somatic cell nuclear transfer
remove egg nucleus, add a somatic cell nucleus of a recipient and continue to grow with new DNA.
Ethical concerns at research stage: Stoping at the fusion stage
cannot use cells to research
Ethical concerns at the rsearch stages: stop at the blastocyst
you can research but run the risk of clones
