Stem Cell and Embryogenesis

Question 1

What is expressed on embryonic stem cells to remain in an undifferentiated state? How do they do this specifically?

Answer 1

Leukemia inhibitory Factor (LIF) and Bone Morphogenetic Protein (BMP).
These proteins released by undifferentiated stem cell receptors REPRESS the MAP Kinase Pathway.

Question 2

What other proteins are expressed on stem cells to enable self-renewal without differentiating?

Answer 2

Sox-2, Oct-4, Nanog (negatively regulate expression of differentiating genes)
Ronin (suppresses txn of differentiation genes)

Question 3

Describe (IPSCs) Induced pluripotent stem cells and where they come from?

Answer 3

IPSCs can self-renew and differentiate into cell types of the tissue’s origin. They are derived from an adult stem cell and forced into a certain expression.

Question 4

Totipotent Cells

Definition and example

Answer 4

From a fertilized zygote to an 8-cell stage after cleavage, these cells make embryonic (fetal) and extra-embryo (placenta) structures.
Ex: Zygote

Question 5

Pluripotent Cells

Definition and Example

Answer 5

Can differentiate into any of the 3 germ layers (ectoderm, mesoderm and endoderm)
Ex: Inner cell mass cells of the blastocoel

Question 6

Multipotent Cells

Definition and Example

Answer 6

Differentiate into cells of a closely related cell-family

Ex: (HSCs) hematopoietic stem cells -> leukocytes, platelets, RBCs, granulocytes…

Question 7

Oligopotent Cells

Definition and Example

Answer 7

Differentiate into a few cells within a certain tissue type

Ex: Lymphoid or myeloid stem cells

Question 8

Unipotent Cells

Definition and Example

Answer 8

Produce ONLY their OWN CELL TYPE; function mainly for self renewal or repair
Ex: Muscle Stem Cell -> fibroblast, muscle cell…
(*These are damage-induced; such as in muscle recovery after workout)

Question 9

Adult Stem Cells

What they’re known for; stem cell type; where found

Answer 9

Self-renewal.
Multipotent
Ex: HSCs and stromal stem cells

Question 10

Embryonic Stem Cells

What they’re known for; stem-cell type; examples

Answer 10

Can be induced to specific phenotypes (ideal for possible stem cell treatment). Dependent on growth factors/ micro env.
Pluripotent.
Ex: Cells within the 4-5 day old blastocyst

Question 11

What 2 ways can Stem Cells be cultured in vitro?

Answer 11

1. On Feeder Layers in Petri dishes (keeps them undifferentiated until induced); tricky to extract
2. Plated with (LIF) inhibitory factor (same as above); $$$

Question 12

Scientists use a ___________ __________ to create markers in order to isolate SCs. What 2 methods are used to identify and isolate specific stem cells?

Answer 12

“Molecular Fingerprint”

1. Flow Cytometry - used to identify SCs in low concentration
2. Fluorescence-activated Cell Sorting - common method used to isolate SCs via lasers

Question 13

What are some ways scientists maintain differentiation of SC’s after they’re isolated?

Answer 13

1. Signal transduction cascade activates transcription factors to enhance txn
2. Synthesis proteins act on chromatin to increase accessibility
3. SC’s make both molecule and receptor if signal-dependent
4. Cells INDUCE neighboring SC’s to remain differentiated

Question 14

What 4 molecular factors can be used to Genetically Reprogram human pluripotent stem cells (PSCs)?

Answer 14

Oct4, Sox2, cMyc (can spawn tumors), Klf4

Question 15

What are some difficult aspects of Cancer Stem Cells (CSCs) that make them hard to treat?

Answer 15

Ability to metastasize (systemic cancer),
Can stay undifferentiated (ex: Stage 5 prostate cancer),
Amplify multi-drug resistant transporters (reduce drug effects)