Cell differentiation/Stem Cells Flashcards by Daniel Marino

stem cell characteristic

self renewing, undiffernentaited, can be tot, pleura, multi, olive, or unipotent, can be undimmed for special functions

cancer-divide slowly, multiple drug resistance, umbridled growth possible

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adult vs embryonic stem cells?

adult

need to be de-differentiated to induce pluripotent
in partiuular regions, generally differentiated

embryoinic-ICM and pluripotent

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how are stem cells indentifiend, isolated, and maintained

isolated-cultured-irradiated mouse fibroblast-grotth/support

idetifed-antibodies to markers CD3R on HSCs-flourensnce

Maintained -LIF-blocks MAPK pathway-prevents differentiation

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stem cells in regen med

tissue repair

organ restoration

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cancer stem cells

self renewal-can result in relapse of cancer if not destroyed

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stem cell properties

unspecialized and can self renew

can be induced to differentiate into cells with special functions (differentiated cell)

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self renewel

assymetric division=stead state conditions-makes differentiated and undifferenteatid cells
-undif stays in niche

Symmetric divisoin=when stem cells must expand-during dev or during injury

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regulation of stem cell self renewel

cell intrinsic

Tfs negatively rg expression of diffenrtiiton promoting genes
dna binding protein (Ronin) supresses trx of differnation-inducing genes

cell extrinsic
-BMp and other stuff block MAPK pathway

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stem cell niche

Chemical and mechanical environemnt
-microenvironemnt

Tissue injury results in respecification of niche-cancer can cause over differentiation

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intesttinal crypty

1:1 ratio between stem and panted cells-need panted cells to divide

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Adult stem cells

Can self renew and differentiate if not differentiated

IPS stem cells-pluripotent stem cells artificially derived from a non-pluripotent

maintain and repair tissue which they find-not pluripotent

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Embryonic

Undifferniated from 5 day preimplantation embryo that is pluripotent

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cancer stem cells (2 types)

drive tumorigenesis and rise to differtitted progeny

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2 types of division

stochasttic-results in two stem cells or two daughter cells

Hierachical division-normal stem cell division

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differentated defintioon

acquired specialized structure and function

can be cancer of cells that look just like cells that should normally be three

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undifferentiated defintion

cell that has not yet acquired a special structure or function

-immature cancer is primitive and does not look like cells in tissue from which it arose

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dedifferentiation

process by which partially or terminally differentiated cell reverts to an earlier dev stage
-holy grail of stem cell research

potency definition and 3 types +example

potential to differentiate

multi-access differentiate into number of cells that are related-hemopoeisis

oligopoent-can differentate into a few spefic ecells-lymphoid

unipotent-can only produce one type of cell-but have self renewal property-muscle cells
-differ from normal cells-self renewel

totipotent vs pluripotent

totipotent-stem cells that are produced from fusion of egg and sperm
-give rise to embryonic and extra embryonic tissues

pluripotent-totipotent cells that can differentiate into cells from any of three germ layers-ectoderm, endoderm, or mesoderm

zygote, embryo potency

zygote-totipotent

embryo-pluripotent (inner cell mass cells)

two type of stem cells in bone marrow

hematopoetic (blood)and stomal (bone, carlidge, fat, connective tissue)

Embryonic stem cells

aka ICM

obtained from 4-5 day old blastocyst

can be cultured in vitro under conditions preventing them from differentiating (need to stop them from differentiating)
-can be cultured to make a particular phenotype

How are stem cells cultured in vitro

Plate ICM cells on layer of fibroblast feeder cells

these bottom cells are inactivated (irradiated) and provide source of growth and attachment factors for ES cells
produces ground substance and fibers of ECm

plate ICM cells onto tissue culture medium containing factors (LIF) that inhibit differentiation
-LIF binds to hetermdimer which activates JAK/STAT signaling-blocks MAPK pathway that would result in differentiation

JAK/STAT and MAPK pathway and LIF

Lif binds to receptor that activates JAK/STAT which inhibits MAPK pathway-stops differentiation

How to identify stem cells

use cell surface markers directed against specific membrane receptors on the stem cells - or flow cytometry for HSC using common markers - analyize 10000s of cells, ells with fluorescent fingerprint-flicked into side tube

Common markers for HSC

hemapoetic stem cell CD34 and Ckit

FACS

most common way to isolate stem cells - flow cytometry - analyize 10000s of cells, cells with fluorescent fingerprint-flicked into side tube

Diffeernation

process where cell becomes more specialized differntation dramatically changes cells shape, size, etc. changes are largely due to highly controlled mods in gene expresssion

How to stimulate cells to differentiate 3

changing chemical comp of culture alter surface of dish (mechanical comp) modify cells by introducing genes

How to maintain differentiated state (4 ways)

gene expression must be maintained 1. TF who se gene is activated can bind to enhancer of own gene 2. synthesize proteins to act on chromatin to leave gene accessible 3. single molecule-cell can make both the molecule and its receptor 4. Cells can interact with neighboring cells-stimulate each other to keep differentiated

Regenerative medicine

Use stem cells to repair or replace damaged tissues - replace damaged tissues and organs - figure out how

mouse with human ear

nude mouse (no immune system) - stem cells from embryonic - probably hard to put back with human immune system

Transplant stem cell-need these things

proliferate extensilvey and make sufficienct quantities of cells differentiate into desired cell types survive after transplant function properly avoid huryting recipient generate tisseust aht will not be rejected

how to get human pluripotent stem cells (5)

1. from morula stage f embryo 2. from ICM of blastocyst 3. from germ cells of fetus 4. from adult (only one without moral issues) 5. somatic cell nuclear transfer (creating ovum with donor nucleus)

IPS (indueced plurpotent stem cells) + important things about this type of stem cell

start of as adult, repgrom back (using nuclear transfer/cell/fusiongenetic reprogramming) - CAN BE PATEINT MATCHED - need 4 out of many candicacn genes to revert it back

challgenges to reprogramming

low effecny genomic insertion tumors incomplete reprogrammng

alternative approaches to reprogramming

chemicals, alternative vectors (plasmids instead of retrovirus), microRNAs, stimulus triggered acquisition of pluripotency (did not work...)

iPS medical research

test drug on stem cells, create organs, repair tissues

Cancer cell theories new vs old

old-all cells are equally tumorgeneic and cancer is prliferative (too many cells reproducing) new-cancer stem cells-properties of normal stem cells especially self-renewal and multi potency - upreulation is due to disruption in reg system mech in stem cell renewal - cancer is a stem cell disorder-not proliferation

CSCs imprtant facts (4)

likely causes relapses and metastasis - self renewal strong-when attack, make more of stem cell during attack of differentiated cells - asymmetric division - divide slowly-plenty of time to repair radio/chemo damage - multiple drug resistance transporters on cell surface - remains in low frequency tho (i think this is good) - unbridlged cell growth mutation-population that expressed genes from drug resistance and antiapop mechs will render chemo ineffective

chemo attacks

bulk of cells-should try to attack cancer stem cells