Stem cells Export

Question 1

Give an example (2) of regenerative medecine achieved through stem cells

Answer 1

Beta-cell replacment for T1D
Goals : production of glucose-responsive, insulin secreting beta cells and functional integration
Challenges : integration, survival, durability of engrafted beta cells, reccurent immune attacks
To date : phase 1-2 clinical trial ongoing

Question 2

Give an example (1) of regenerative medecine achieved through stem cells

Answer 2

Stem cell trials for repairing retinal pigment epithelium in AMD (age-related macular degeneration) :
Goals : restoration of function with iPSCs
Challenges : precise localized delivery, potentially oncogenic mutation led to halt of trial

Question 3

What are the challenges of pluripotent stem cells ?

Answer 3

Cost of iPSC culture
Optimization of the differentiation protocol
Abscence of data on the whole body (compared to in vivo studies)

Question 4

What are the advantages of pluripotent stem cells ?

Answer 4

Unlimited source human cells or tissues
Possibility to derive from PSCs cells or tissues of interest
Identification of targets for therapy
Identification of active drugs
Prediction of drug toxicology

Question 5

What are the causes of attrition in drug development ?

Answer 5

Disrepancies with the animal models used in preclinical studies
Differences in the pathophysiology (immune diseases, CNS)
Differences in the drug toxicology and metabolism
Diffferences among humans in drug responses
Different genetic backgrounds
Differences difficult to predict

Question 6

What are interesting observations made fromm NPCs derived from Twin-DS-iPSCs ?

Answer 6

Decreased number, impaired proliferation and increased cell death
Shift from neuronal to astroglial and oligodendroglial phenotype
Reduced number and length of neurites (axons and dendrites)
Reduced number of glutamatergic neurons
Increased DYRK1A expression and activity

Question 7

What are the effects of inhibiting DYRK1A by shRNA ?

Answer 7

Imrpoved neurogenesis

Question 8

Into what cells can T21-iPSCs be used to study ?

Answer 8

iPSCs from monozygotic twins discordant for trisomy 21 (D21-iPSCs & T21-iPSCs) can be used to study :
neural cells (cognitive impairment)
hematopoietic cells and B lymphocytes (AML, ALL)
skeletal muscles cells (muscle weakness)
trophoblastic cells (spontaneous abortion)

Question 9

What is the challenge with differentiating embryonic stem cells into specialized cells ?

Answer 9

Finding the correct conditions (cytokines, growth factors, mediums) that drive the differentiation of an ECS into a mature cell

Question 10

How do you generate chimeric mice ?

Answer 10

Inject iPSCs into the blastocyst
Transfer the blastocyst into the uterus of the recipient
Chimeric mouse
??? Profit

Question 11

Briefly describe the diff. of iPSCs into EBs

Answer 11

iPSCs are suspended to form embryoid bodies (day 4)
They then are adhered to form differentiated tissue with all 3 germ layers (day 21)

Question 12

What criterias define iPSCs ?

Answer 12

Morphology similar to ESCs
Unlimited self-renewal
Transgene silencing
Expression of pluripotency markers
In vitro diff. into derivatives of the 3 germ layers

Question 13

What 3 methods exist to reprogram somatic cells into iPSCs ?

Answer 13

Retroviral or lentiviral transduction
Adenoviral transduction
Plasmid transfection

Question 14

What factors were used to derive the first human iPSCs ?

Answer 14

Yamanaka induced pluripotent stem cells fromm human fibroblasts with 4 factors :
oct3/4
sox2
c-myc
klf4

Question 15

What are induced pluripotent stem cells ?

Answer 15

A type of stem cell by reprogramming adult somatic ells into pluripotent stem cells. First done with mouse induced pluripotent stem cells by Yamanaka S. in Japan by identifying 24 candidate genes that play a pivotal role in the maintenance of ESC identity.

Question 16

Briefly define mesenchymal stem cells

Answer 16

Origin in the bone marrow
gives rise to :
bone
fat
cartilage
They are currently being investigated for :
promoting angiogenesis
anti-inflammatory properties
stimulate endogenous cell formation

Question 17

Briefly define gut stem cells (GSCs)

Answer 17

Origin in the small intestin
give rise to :
goblet cells
endocrine cells
columnar cells

Question 18

Briefly define neural stem cells (NSCs)

Answer 18

Origin in specific areas of the brain
gives rise to :
neurons
oligodendrocytes
astrocytes (type 1 and 2)

Question 19

Briefly define hematopoietic stem cells

Answer 19

Origin the bone marrow
Give rise to specialized blood cell types :
NK cells
Platelets
macrophages
etc.

Question 20

What are commited progenitors ?

Answer 20

“transient amplifying cells”
multipotent
divide rapidly
no self-renewal
lead to specialized cells

Question 21

Where and what is the role of tissue stem cells?

Answer 21

Found throughout the whole body to replace damaged or used up cells. They are multipotent as they can make multiple types of specialized cells, but not all.

Question 22

Give an example of genome editing used in a human embryo

Answer 22

Crispr-Cas9 can be used to knock out the CCR5 gene, the “doorway” to HIV into human cells. Used by chinese professor for IVF with HIV-positive fathers

Question 23

What is the status of human embryonic stem cells reserach in CH ?

Answer 23

Permissive with restrictions : hESC research is allowed with IVF embryos up to 7 days post-fertilization (informed consent). Cloning and creations of embryos for research is prohibited.

Question 24

What are EBs composed of ?

Answer 24

Embryoid bodies are composed of derivatives of the 3 germ layers : ectoderm, mesoderm and endoderm

Question 25

What are the “core regulatory circuits” that determine pluripotency ?

Answer 25

OCT3/4 : maintains self-renewancy of pluripotent stem cells
SOX2 : essential for embryonic dvlp. Downregulation of SOX2 leads to differentiation of ESCs
NANOG : Necessary to promote pluripotency in combination with OCT3/4 and SOX2

Question 26

Give characteristics of embryonic stem cells in culture

Answer 26

Self-renewal (copying) : unlimited proliferation in vitro
Possibilty of obtaining an unlimited number of cells
Normal karyotype (if no chr. aberrations)
Proliferation as 2D colonies
Need of feeder cells (embryonic fibroblasts) or extracellular matrix (matrigel) to culture
Specific media needed for proliferation and pluripotency maintenance
Basic fibroblast growth factor (bFGF)

Question 27

Give the characteristics of a blastocyst

Answer 27

Days 5-6
64 - 128 cells
trophoblast present
inner cell mass

Question 28

Where are tissue stem cells found ?

Answer 28

In the fetus, baby and throughout life

Question 29

Where are embryonic stem cells found ?

Answer 29

In the inner cell mass of the blastocyst, a very early embryo (5 to 14 days)

Question 30

Classify each of these stem cells into the 4 known categories of stem cells : esc, ipsc, differentiated cells, zygote, adult stem cell.

Answer 30

Totipotent : zygote
Pluripotent : ipsc, embryonic stem cells
Multipotent : adult stem cell
Unipotent : differentiated cell

Question 31

What are the 4 classes of stem cells ?

Answer 31

Totipotent stem cells : found only in early embryos, each cell can form a complete organism
Pluripotent stem cell : found in the undifferentiated inner cell mass of the blastocyst (5 to 14 days) and can form any of the 200 cell types in the body
Multipotent : derived from fetal tissue, cord blood and adult stem cells. These are already differentiated, but can form a number of tissues
Unipotent : able to contribute to only one mature cell type but still able to self-renew

Question 32

Why do stem cells self-renew and differentiate ?

Answer 32

Self renewal : to maintain the stem cell pool
Differentiation : to replace dead or damaged cells throughout life

Question 33

What are the 2 charcteristics of stem cells ?

Answer 33

Capable of self-renewal (copying)
Differentiation into specialized cells

Question 34

Created on OmniSets

Answer 34

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