Lecture 39

Question 1

Compare the characteristics of Totipotent cells, Pluripotent cells, and Multipotent cells. (include examples of all 3 types of cells)

Answer 1

Totipotency: ability of a cell to give rise to all cells of an organism, including embryonic and all extra-embryonic tissues ex. zygote

Pluripotency: ability of a cell to give rise to all cells of the embryo and subsequently adult tissues (NOT able to become extra-embryonic cells) ex. embryonic stem cells

Multipotency: ability of a cell to give rise to different cell types of a given lineage ex. adult stem cells

Question 2

ES cells are capable of proliferating indefinitely in culture with _____ _____ potential. Compare ES cells with zygotes in terms of the types of tissues they may be able to differentiate into.

Answer 2

unrestricted developmental

ES cells are incapable of generating a full organism, unlike zygotes, which can

Question 3

In terms of embryonic stem cells, what is their source? describe the type of potency these types of cells have and how they are harvested.

Answer 3

the “inner cell mass” is the source of embryonic stem cells that are pluripotent

This mass is “pulled” from the blastocyst stage

Question 4

What happens if you were to harvest an inner cell mass from one cell and they put it back into a blastocyst?

Answer 4

the inner cell mass will integrate well with the embryo is added to

(this is how scientists can add human inner cell mass to a mouse blastocyst and make it exhibit human hemoglobin. this is useful to study how a human cell may react to a substance)

Question 5

Define trophoblast and a blastocyst cavity

Answer 5

trophoblast: the cells that compose the most external “membrane” of a blastocyst

Blastocyst cavity: is the hollow space on the inside of a blastocyst

Question 6

Define trophoblast and a blastocyst cavity

Answer 6

trophoblast: the cells that compose the most external “membrane” of a blastocyst

Blastocyst cavity: is the hollow space on the inside of a blastocyst

Question 7

What do cartilage, bone, skin, nerves, gut, and respiratory lining all have in common in terms of stem cells?

Answer 7

embryonic stem cells injected into a host animal can give rise to all of these types of tissue

Question 8

Define teratoma. What is a common source of these?

Answer 8

teratoma: a disorganized growth with no axis formation or segmentation

if you inject ES (embryonic stem) cells into an embryo at a later stage or into an adult, they will fail to receive the appropriate cues for proper differentiation. forms teratoma

Question 9

name 3 ways in which ES cells could be used in medicine

Answer 9

used to study disease mechanisms

test chemical compounds that show promise (in a dish without harming a conscious person)

could be derived from a person and used to screen libraries of compounds for customized treatment strategies

Question 10

Define SCeNT. Explain the steps in which it is conducted.

Answer 10

SCeNT (somatic cell nuclear transfer): combines cloning methods with embryonic stem cell technology to produce cells that are custom-made for the pt.

nucleus taken from somatic cell of the pt and injected into the oocyte of a donor (replacing the original nucleus there)

blastocyst is generated from this hybrid oocyte and the ES cells are isolated (by removal of the inner cell mass)

Question 11

where does the donor oocyte for SCeNT come from?

Answer 11

preferably the pt themself but it could also be taken from a close relative.

I could grow new non diabetic pancreatic cells, using my mother’s oocyte as a donor

Question 12

What must be directly manipulated in order to attempt to convert adult cells into ES-like cells? how well does this usually work?

Answer 12

gene expression

the normal yield is low

Question 13

List the 4 gene regulatory proteins that are considered to be key determinants of ES cell characteristics. what is the term that is used to categorize these genes?

Answer 13

Oct4

Sox2

Klf4

Myc

(OMSK)

“candidate genes”

Question 14

Exactly what do you need to do in order to stimulate ES-like cells in an adult, with the ability to differentiate into other cell types?

Answer 14

over express the 4 candidate genes in a cell and then inject it into a fibroblast in the pt

Question 15

which of the 4 candidate genes really only makes the ES-like cell stimulation process more efficient and has been shown to be less necessary than the others? explain exactly what it does

Answer 15

Myc

up regulates cell proliferation and loosens the chromatin structure (makes it easier for the other 3 genes to do their job)

Question 16

what do Oct4, Sox2, and Kif4 specifically do when added to an adult cell?

Answer 16

they up regulate embryonic stem cell genes

and down regulate differentiation genes that were previously activated in the adult cells

Question 17

List the 2 challenges with inducing stem cells in adults that are not considered to be “technical challenges”. How can this be avoided?

Answer 17

Tissue/immune rejection

Genetic and epigenetic aberrations

These can be avoided by using the pt’s own cells to manipulate or a close relatives cells

Question 18

List the 3 main pro’s of using stem cells that are harvest from umbilical cord blood of a newborn baby

Answer 18

Cells are undifferentiated

No ethical problem

no genetic manipulations (to induce stem cell characteristics) are needed bc they are already stem cells

Question 19

Describe what exactly composes the artificial skin barriers that are used in the repair of skin today (especially burn patients). Explain what reaction the damaged skin has to this artificial skin and why it works

Answer 19

a matrix of collagen and glycosaminoglycan contained within a thin membrane of silicone

fibroblasts and blood capillaries from the pt’s tissue migrate to the artificial skin and reform the CT underneath

Then the artificial skin is replaced with cultured epidermal cells to completely reconstruct the skin

Question 20

When cultures ES or iPS cells are exposed to retinoic acid, what type of cell forms?

Answer 20

Neuron

Question 21

When cultures ES or iPS cells are exposed to retinoic acid and the insulin / parathyroid hormone, what type of cell forms?

Answer 21

Adipocyte

Question 22

When cultures ES or iPS cells are exposed to macropharge colony stimulating factor, interleukin-3, and interleukin-1, what type of cell forms?

Answer 22

Macrophage

Question 23

When cultures ES or iPS cells are exposed to dibutyryl cAMP, and retinoic acid, what type of cell forms?

Answer 23

Smooth muscle cell

Question 24

When cultures ES or iPS cells are exposed to fibroblast growth facto, fibroblast growth factor 2, epidermal growth factor, and platelet derived growth factor, what type of cell forms?

Answer 24

Astrocyte and oligodendrocytes

Question 25

explain what “high throughput screening” is

Answer 25

testing chemical compounds that show promise

(ES cells could theoretically be used to grow human tissues that could be very useful in high throughput screening tests)

Question 26

name a strategy besides SCeNT that is used to induce ES cell-like properties in adult somatic cells.

Answer 26

iPS (Induced Pluripotent Stem cells)

Question 27

Explain how a fibroblast could be reprogrammed to create induced pluripotent stem cells (iPS)

Answer 27

Kif4, Oct4, Sox2, and Myc (efficiency gene) can be added so that they will act on Nanog

Question 28

Explain how Induced Pluripotent Stem Cells (iPSC’s) can be created from a somatic cell (NOT the 4 candidate genes, a more broad explanation)

Answer 28

somatic cells can be reprogrammed to be iPSC’s

expose a somatic cell tot defined, limited sets of transcription factors (genes for stem-ness)