Stem Cells Flashcards
What is a stem cell
A cell that can either renew itself, reproduce itself or give rise to more differentiated cell types
What is the difference between totipotency, pluripotency and multipotency
Totipotency means the stem cell can make an entire organism, multipotency means the cell can give rise to all the embryonic tissues and adult tissues but cannot form extraembryonic structures and multipotency means a stem cell can give rise to different tissues in a given lineage. Refer to the picture
What are the different types of stem cells
- Adult stem cells, like the mesenchymal stem cells 2. Germ line stem cells 3. Fetal stem cells 4. Cord blood stem cells 5. hESC 6. Induced pluripotent stem cells - iPSCs
What are the characteristics of adult stem cells
These are stem cells that respond to tissue damage and repair. In order to do this restrictions are placed on the stem cell to specialize in a determined cell, these limits are imposed by powerful molecular restraints and are heritable during many rounds of replication. Some cells exhibit freedom from these restrictions in an altered environment do exhibit plasticity
What signaling induced proliferation and differentiation of hematopoietic stem cells found in the bone marrow
WNT signaling, NOTCH signaling and N cadherin signaling
What are the properties of hESCs
They are derived from pluripotent cell population of 5 day old human embryos created during IVF before more specialized tissue of the embryo begin to form They can be grown indefinitely in culture. Also they can differentiate into both somatic and germ line cells
How are embryonic stem cells derived
When a blastocyst forms we take out some of the inner cells and culture them in a petri dish
What happens when you inject hESCs into the skin of a mouse
They give rise to poorly differentiated teratomas. Teratomas do not display axis formation or segmentation. However it is important to know that hESCs cannot give rise to generating a body plan on their own. They need external signaling to organize their growth
What happens when we stop hESCs multiplication by changing their culture in a petri dish
They differentiate into all kinds of different cells like one may find muscle and nerve cells on the same petri dish
Can you make a human from a hESCs?
No. You can only do that from a zygote
Compare embryonic stem cells to adult stem cells
- It is popularly believed that adult stem cells cannot replace hESCs. 2. Hence both sources of stem cells are studied simultaneously 3. They each offer cures and are not replacements for one another
What is SCNT
In somatic cell nuclear transfer, custom cells are made for the patient to avoid immune rejection and these cells can be grown in a petri dish and studies for drug effectiveness or can be used for other clinical research purposes to tailor treatment to that individual. Also this avoids developing genetic therapy via the iPSCs which is controversial due to genetic reasons
Explain this process in detail
- Take an egg cell and either kill off or take out the nucleus 2. Take the somatic cell of the patient and fuse it with the egg cell (this egg cell doesn’t have any nucleus) 3. Induce cell proliferation, usually done by electrical stimulus 4. Extract inner cell mass and culture them
How is SCNT to treat diseases
The inner cell mass can be cultured and then allowed to proliferate. Then by introducing the right factors they can be made to differentiate into the desired cells that are needed for therapy like cardiomyocytes, pancreatic cells, etc etc. Cells obtained in this manner will not be rejected by the immune system of the patient
