Stem Cells Flashcards
What is a stem cell?
A primitive cell that can self-renew or give rise to more specialized cell types (differentiated)
What does a stem cell typically produce?
one stem cell and one daughter cell
What are the major characteristics of stem cells?
- Not terminally differentiated
- can divide without limit
- Under slow divison
- when divided = one stem cell characteristics, one with ability to differentiate
What is totipotency (embryonic stem cell)?
Ability to give rise to all cells of an organism, including embryonic and extraembryonic tissues (ZYGOTE)
What is Pluripotency (embryonic stem cell)?
Ability to give rise to all cells of the embryo and adult tissues (blastocyst)
What is multipotency (adult/somatic stem cell)?
Ability to give rise to different cell types of a given lineage (blood cells, connective tissue)
What are the tree main things multipotent stem cells can become?
the ectoderm, endoderm, and mesoderm
What are founder stem cells?
(small -> large) always present in organ tissues and determine organ size through signaling
What are transit amplifying cells?
Cells that divide frequently, giving one stem cell and one daughter cell with stem cell characteristics - > commited, # divisions finite
What are the two ways stem cells are maintained?
Divisional and environmental asymmetry
What is division asymmetry?
creates 2 cells, one with stem cell character. and one with factors that give it the ability to differentiate
What is environmental asymmetry?
Makes 2 identical cells that environment may influece or alter one of the cells
What is immortal strand hypothesis?
one stem cell has original strand of DNA preserved from stem cell, another gets newly synthesized strand
Characteristics of embryonic stem cells?
- derived from blastocyst
- proliferate indefinitely
- forms any body part
What happens when embryonic stem cells are injected into an embryo at a later stage or into an adult ?
They fail to receive proper cues for proper differentation leading to tertomas.
How are ES cells grown?
in vitro using mast cells from the blastocyst, irradiated with mouse fibroblast, growing cells
What transcription factors are essential for establishment and maintenance of pluripotent stem cells in the embryo that embryonic stem cells express?
Nanog, Oct4, Sox2, FoxD3 (along with Cripto, GDF3 found in pluripotent)
What and where are adult stem cells?
They are found in tissues and repond to demands of growth/repair. Strict population of genes expressed, meaning platicity is extremely low (compared to ES cells)
Why are teratomas more rare in adult stem cell applications?
Because adult stem cells are multipotent and are very limited to what they can become, unlike ES cells.
What can hematopoietic stem cells become and where are they derived from?
Derived from bone marrow, they can become blood components
What can mesenchymal (stromal) stem cells become and where are they derived from?
they can become connective tissues and tissues and are derived from bone marrow
What is cord blood?
an adult stem cell that is undifferentiated and need no gene manipulation. can be used to treat your own disease down the road
what therapies can adult stem cells be used for?
regenerate neuronal cells post-stroke
What are some major regenerative medicine issues/disadvantages for mature and early stem cells?
(Mature) 1. limited longevity 2. Difficult to find 3. Many unknowns 4. Multipotent (Early) 1. Immune rejections 2. Difficult to control
What is somatic cell nuclear transfer (SCNT)?
Nucleus is taken from somatic cell of patient and injected in to the oocyte of a donor replacing the oocyte nucleus CAUSES CLONING = BAD*
What are the key determinants of ES cell character?
Gene regulatory proteins : Oct3/4, Sox2, Myc, KIf4
What are alternative sources for human ES cells?
induced pluripotent stem cells (iPS)
somatic cell nuclear transfer
Why are induced pluripotenstem cells (iPS) very bad?
They are replicated using viruses in recombinant DNA! therefore there is a much higher rate of tertomas than ES.
