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47 Cards in this Set

  • Front
  • Back
How often do humans renew?
Every 7 years
Although it's being challenged what tissues do not renew?
Brain and Heart
What is the challenge for the next generation's physicians and scientists?
To accelerate this process of regeneration for therapy
What is beginning to bypass gene therapy in terms of importance for therapeutic regeneration?
Stem cell therapy
What is the definition of a stem cell?
A cell present in an embryo or adult that has the potential to repopulate tissues - regenerate them.
What capacity do Embryonic Stem Cells have?
Pluripotent - can be programmed to reconstitute ANY tissue in the human body.
What are ESCs in addition to being pluripotent?
Totipotent
What does Totipotent mean?
ESCs have the potential to make a whole embryo
Are Adult stem cells totipotent?
No - they can only reconstitute part of the body.
If adults HAVE stem cells, why is it necessary to administer them for therapy?
Because humans are so evolved that their tissues don't repair well so you have to give extra repair cells.
What animals have the best regenerative potential?
Invertebrates and amphibians
What have intermediate regenerative potential?
Rats and cows
What has the least regenerative potential?
Rhesus monkeys and humans
3 commonly recognized sources of stem cells:
1. Embryonic
2. adult
3. Restricted potential adult stem cells
Embryonic stem cells:
-Capacity
-Site
Capacity: pluri/totipotent
Site: inner cell mass of the blastocyst (1wk old embryo)
Adult Stem Cells:
-Capacity
-Site
Capacity: multipotent
Site: bone marrow
Restricted Potential Adult SCs:
-Capacity
-Site
Capacity: unipotent
Site: niches in individual body tissues
ESC is synonomous with
Pluripotent
How many different types of cells can result from a pluripotent stem cell?
Over 200 - all the different types in the body.
How long are the telomeres in ESCs?
Longest known.
What happens when you culture ESCs?
They spontaneously differentiate into any of the differentiated cell types of the human body.
Why is it bad that they differentiate spontaneously?
If you want a specific type of cell, say cardiac myocyte, you have to figure out how to engineer that to happen on cue.
What does a culture have to contain to grow ESCs?
Mouse feeder cells + bovine serum
Why is it bad to grow ESCs on mouse/bovine media?
They can transmit zoonotic diseases if used for therapy
What is the solution?
FGF-2 fibroblast growth factor has been engineered to overcome that challenge.
What stimulates cardiac cells to form in the embryo?
Precardiac endoderm stimulates neighboring mesoderm to become precardiac during gastrulation.
What are the 3 important growth factors made by precardiac endoderm that stimulate mesoderm to differentiate into beating heart cells?
-BMP (bone morphogen protein)
-FGF (fibroblast growth factor)
-Activin-A
So what happens when you grow ESCs on a plate of precardiac endoderm?
It will induce the formation of beating cardiac myocytes.
What are the sources of human ESCs?
NIH approved lines
What are the criteria for using human ESCs?
-Inner cell mass must be removed
so the Embryo can't develop
-Must have been created for reproductive purposes only
-Informed constant must be obtained from donors
-No financial inducement
What does SCNT stand for?
Somatic cell nuclear transplant
How is SCNT somatic cell nuclear transfer done?
A diploid nucleus (complete) is removed from an adult somatic cell and put into an anucleate female ovum
What is the result of SCNT?
A clonal blastocyst - embryo
What is the process of SCNT called?
Reproductive cloning - it creates a genetically identical baby from the adult nucleus donor.
Why is SCNT risky?
Because you could make a whole human being - slippery slope.
What is Therapeutic Cloning?
SCNT, but stopped at the blastocyst stage and cells used there.
Is it more ethically acceptable to create a gene deletion in the blastocyst derived from SCNT?
No, it's just making a defective embryo.
Does SCNT create a new genetically unique individual? Why/ why not?
No - it doesn't involve the union of an egg and sperm.
So the positive side of SCNT is:
Unique new life is neither created nor destroyed.
What is the major justification for therapeutic cloning?
Immune rejection
Why is immune rejection the major justification for it?
Because the genotype of the recipient is the same as that of the diploid nucleus donor.
What is the major strength of ESCs?
They generate the widest variety of tissues for therapeutic transplantation (SCNT)
What are ESCs' 4 main weaknesses?
1. Limited availability/ethics
2. Transmission of zoonoses
3. Immune rejection if not derived by scnt
4. Tumorigenic if not differentiated before transplant
Can adult somatic cells be induced to become pluripotent?
Yes!
What transcription factors can induce mature human cells to become pluripotent?
-Sox2
-Oct 3/4
-c-Myc
-Klf4 (nanog)
Another potential source of pluripotent cells other than from embryos:
Amniotic fluid
What is demanded for research on pluripotent cells at this point?
Bonafide pluripotent ESCs