stem cells

Question 1

characteristics of stem cells?

Answer 1

Primitive cell that can self-renew or give rise to more specialized cell types

Single stem cell can become multiple functional cell types

Not terminally differentiated, can divide without limit, undergoes slow division, gives rise to cells that have ability to be differentiated

Question 2

Self renewal

Answer 2

Stem cells divide to make more stem cells

Question 3

what are Founder stem cells

and their significance?

Answer 3

Proportions of body parts are determined early

Each tissue has fixed number of founder cell populations

Programmed to have fixed number of divisions

Controlled by short range signals that operate a few hundred cell diameters

Defines the size of large final structures

Question 4

Transit amplifying cells, what are they and what do they do?

Answer 4

Cells that divide frequently

Transit from a cell with stem cell characteristics to a differentiated cells

Leaves the basal layer and incorporated into the layers above

Programmed to have limited number of divisions -> FINITE

Part of strategy for growth control
Committed cells

Question 5

what is .Immortal strand hypothesis?

Answer 5

Some tissues’ stem cells selectively retain original DNA

A way to prevent genetic errors in stem cells

This daughter cell will retain stem cell characteristics

Original strand of DNA in stem cell from generation to generation while second cell gets the newly synthesized DNA

Question 6

Maintenance of Stem Cells, how is it done?

Answer 6

50% of daughter cells must remain stem cells -> retain original DNA

Accomplished by:
Divisional Asymmetry
and
Environmental Asymmetry

Question 7

what is divisional asymmetry?

Answer 7

create 2 cells, one with stem cell characteristics and another with factors that give it ability to differentiate

Question 8

what is Environmental Asymmetry?

Answer 8

Division makes 2 identical cells but environment may influence/alter 1 cell
Methylation, epigenetics, etc.

Question 9

Multipotency? what is it?

Answer 9

Ability to give rise to different cell types of a given lineage

Ex: Adult Stem Cells - RBCs, Intestinal cell lining
Maintain tissue homeostasis, partially committed

Question 10

Pluripotency? what is it?

Answer 10

Ability to give rise to all cells of embryo and subsequently adult tissues (embryonic stem cells)

Ex: Blastocyst

Question 11

Totipotency? what is it?

Answer 11

ability to give rise to all cells of an organism including embryonic and extraembryonic tissues.

Ex: Zygote

Question 12

Adult stem cells? what is significance about them?

Answer 12

Multipotent- able to give rise to different cell types of a given lineage

Ex: RBCs, intestinal cell lining, hair and nails
Limited clinical use

Question 13

Fetal stem cells? what is the significance of them?

Answer 13

Pluripotent- will differentiate into different tissues

Derives from inner mass of cells in blastocyst

Question 14

Cord blood stem cells? what is the significance

Answer 14

Another example of adult stem cell

Undifferentiated , no gene manipulation

Found in cord tissue

Question 15

Current treatments with cord blood stem cells?

Answer 15

Leukemia
Immune Deficiency Disease
Myeloma
Sickle Cell Anemia
Lymphoma
Thalassemia

Question 16

embryonic stem cells?

Answer 16

Ability to differentiate into a wide range of tissues

Do not display axis formation or segmentation

ES cells on their own are incapable of generating a body plan

Cartilage, bone, skin, nerves, gut, and respiratory lining form when ES cells are injected into host animals

This lack of organization is also seen when ES cells differentiate in vitro

Pluripotent, derived from blastocyst, integrate in embryo, proliferate indefinitely

can form teratomas

Question 17

what are the types of stem cells there are?

Answer 17

Adult- under-differentiated and generate cell types in the tissues in which they reside, Can be Multipotent

embryonic-pluripotent

Question 18

what decides what type of stem cell is made?

Answer 18

Stages involve multiple factors that combine to produce epigenetic markers in cell’s DNA that restrict DNA expression, thus they the type of cell that the stem cell will turn into

Question 19

DNA expression can pass on to daughter cells how?

Answer 19

through cell division

Question 20

immortal strand hypothesis

Answer 20

Or daughter cells can retain stem cell status and capability for long-term renewal

Question 21

when are totipotent cells made?

Answer 21

After fertilization, the zygote undergoes equal divisions to create more cells.

Considered totipotent

Question 22

How are pluripotent stem cells made? what can they make?

Answer 22

when blastocyst forms, and an inner cell mass develops

Give rise to many cell types but not all cell types necessary for fetal development

Question 23

Four Transcription Factors that induce adult cells to show properties of ES cells?

Answer 23

Oct4, Sox2, Nanog, and Lin28

Embryonic Stem Cells (ES Cells) hold great therapeutic potential

Can make patient-specific iPS for specialized therapies

Question 24

Describe adult stem cell differentiation

Answer 24

Reliable, highly reproducible results, establishes pluripotency

In vitro and in vivo, can regenerate neuronal cells

Harvested stem cells retain properties of original tissue type

Restricted capacity and growth potential

Provides a solid theoretical and experimental foundation to:
Induce development of specialized cell types

Question 25

what has been successfully treated with mouse ES cells?

Answer 25

Severe immune deficiency
Diabetes
Parkinson’s Disease
Spinal injury
Demyelination
Myocardial Infarction

Question 26

Hematopoietic and stromal stem cell differentiation, where do they come from?

Answer 26

Both come from bone marrow

Differ in what they can be differentiated as

Question 27

MSC, what do they become?

Answer 27

connective tissue and bone

Found in Wharton’s jelly, bone marrow, adipose and tooth pulp
Differentiate into 
Bone tissue
Cartilage tissue
Fat tissue
Heart tissue
Liver tissue

Question 28

hematopoietic stem cells? what do they become?

Answer 28

blood components

Found in cord blood, bone marrow and peripheral blood

Differentiate into
Platelets
RBCs
WBCs

Question 29

what happens when embryonic stem cells are put back in to the blastocyst?

Answer 29

integrate well with the embryo

Develop into different cell types

If injected into an embryo at a later stage or into an adult, they fail to receive approximate sequence of cues for proper differentiation

can become tumor

Question 30

how can human es cells come from embryos?

Answer 30

Serum containing medium plus mouse or human embryonic fibroblast feeder cells

Serum free medium with serum replacement and basic FGF

LIF and related cytokines have no effect

Question 31

what is the big problem if adult stem cells are not from the host? what is the solution?

Answer 31

Immune rejection

Creation of leukocyte antigen-typed stem cell banks

Question 32

what is Somatic Cell nuclear transfer?

Answer 32

Nucleus taken from somatic cell of patient and injected into egg of a donor replacing the local nucleus

Blastocyst generated from this hybrid oocyte and ES cells isolated

Solves tissue rejection - HUGE Therapeutic potential

Question 33

issues with SCNT?

Answer 33

Prohibiting cloning at fusion step restricts therapeutic application

Prohibiting implantation of SCNT product restricts reproductive cloning but allows therapeutic research to continue

Question 34

Induced Pluripotent Stem (iPS) cells

Answer 34

Patient specific IPS cells for treatment

High possibility for teratomas

Question 35

what enzyme do stem cells have before they become differentiated?

Answer 35

telomerase