Stem Cells & Differentiation Flashcards
(23 cards)
What types of tissues can embryonic stem cells become?
ALL TYPES
pluripotent
How are adult stem cells limited?
typically limited to similar type
What is a stem cell niche?
Micro environment where stem cells are found
- interacts with cells to regulate fate
Ex) hemolytic stem cells -> osteoblast niche
Ex) sin stem cells -> basement membrane
Why is it important to regulate stem cell division?
Avoid unnecessary depletion
- ensure supply available to maintain homeostasis/ respond to illness/ injury
What types of signals induce stem cells to divide?
Humoral Structural Paracrine Neural Physical Metabolites
How do we know what stem cells give rise to other cells in a tissue?
Hans exp:
know Wnt influences stem cell division-> are Wnt target genes expressed in rare cells?
=> label using knock out cross bred mice
- 1 dose of tamoxifen to activate
=> followo proliferation of cells from crypt to tip of villi
- 3 total cell types -> multipotent
- CBC cells are true stem cells of intestine
What is one important function of the Wnt pathway?
Induce stem cell division
How can you follow stem cell
Breed with activatable (removeable stop casette)
activate marker 1 x
=> watch proliferation
How do you identify stem cells?
Follow Wnt signaling
Knockout suspected niches, measure response
What does new evidence indicate to be a potential capability of hemolytic stem cells?
repairing other tissue types
What evidence suggest the plasticity of stem cells?
Grafted/ donated stem cells from adult donor can differentiate and be identified in multiple tissue areas (some unexpected)
What happens during adult stem cell reprogramming?
Cells removed -> plated -> exposed to factors->
=> 2 weeks later = embryo
Reprograming factors strip programing of genetic expression (i.e. skin cell has liver genes supressed and skin genes up regulated- > re programers come in and turn genome back to new)
What are the benefits of adult stem cell reprograming?
0 ethical problems (no destruction of human fetus)
0 risk of rejection (self)
What was Dr Gurdon’s experiment and what did it prove?
Placed adult skin cell from frog in fertilized embryo -> viable adult frog resulted
PROVED:
adult cells have all of the necessary genes to form entire organism - they are just preferentially activates/ expressed
also proved that factors necessary to reprogram are in oocyte cytoplasm
What does induced pluripotent stem cell mean?
the cell had differentiated, but due to exposure to reprogramming factors in now capable of expressing genes differently and become any cell type
What are the 4 factors necessary to reprogram adult stem cells?
Oct3/4
Sox2
c-Myc
Klf4
What are some of the benefits of reprogramed IPS cells?
can be stored indefinitely
can be genetically modified
0 immune response
newborn
- Telomeres rejuvinated!!!
Why are retro viruses a poor option for integrating reprogramming into cells?
they insert at random into the genome => strong possibility of oncogenic event
What is an alternative of viral vectors?
mRNA
- degrades
- translates into reprograming factors -> leaves
What technologies allow specific cutting of Genomes of IPS cells for genetic modification?
zinc fingers
Talen
crisper
How can stem cells be used to treat cancer?
bone marrow transplants
What are other treatments that stem cells are used for?
severe burns
(tx over 30 years ago-> still alive)
Repair eyesight
(stem cells from limbus (betwn cornea and conjunctiva)
Grow RBCs
What common problem encountered in cancer treatment may be overcome if stem cells are considered?
cancer cells treated -> die -> some surrvive -> cancer returns
cancer may be returning due to stem cells that survive tx => if we treat and kill stem cells -> cancer will not grow -> can be removed/ txed
