2. Stem cells I

Question 1

What is the undifferentiated state of stem cells?

Answer 1

Primitive state with high developmental potential

Can give rise to multiple cell types

Question 2

Define self-renewal capability in stem cells.

Answer 2

Ability to proliferate and make more stem cells

Maintains stem cell pool

Question 3

What is the differentiation ability of stem cells?

Answer 3

Can generate committed progenitors that further differentiate into mature, functional cells

Question 4

Describe asymmetric self-renewal division.

Answer 4

Produces one stem cell and one committed progenitor

Maintains stem cell pool while generating differentiated cells

Question 5

What occurs during symmetric differentiating division?

Answer 5

Produces two identical committed progenitors that both differentiate into mature cells

Reduces stem cell pool

Question 6

What is symmetric self-renewal division?

Answer 6

Produces two identical stem cells

Expands stem cell pool; important during development and tissue regeneration

Question 7

True or False: Imbalances in stem cell division modes can lead to disease.

Answer 7

True

Excessive asymmetric/symmetric differentiating divisions can deplete stem cells; excessive symmetric self-renewal can lead to cancer

Question 8

What is totipotency?

Answer 8

Highest developmental potential; can form entire embryo plus extraembryonic tissues

Only zygote and early blastomeres (4-8 cell stage) are totipotent

Question 9

Define pluripotency.

Answer 9

Can form all tissues of the embryo proper but cannot form extraembryonic tissues

Example: Inner cell mass (ICM) cells/embryonic stem cells

Question 10

What is multipotency?

Answer 10

More restricted potential; can form multiple cell types within a specific lineage or tissue

Example: Hematopoietic stem cells, neural stem cells

Question 11

What does oligopotency refer to?

Answer 11

Can form a few cell types within a specific lineage

Example: Myeloid progenitors

Question 12

What is unipotency?

Answer 12

Can form only one cell type

Example: Spermatogonial stem cells

Question 13

When were embryonic stem cells (ESCs) first isolated?

Answer 13

Early 1980s by Gail Martin and Martin Evans

Question 14

What was used to culture embryonic stem cells?

Answer 14

Feeder cells that provided essential nutrients

Question 15

What growth factor was discovered by Gail Martin for differentiating cells into germ layers?

Answer 15

FGF

Question 16

What are the key transcription factors that maintain pluripotency?

Answer 16

• Oct4
• Sox2
• Nanog

Question 17

What happens to transcription factors during embryonic development?

Answer 17

Must be silenced at appropriate time to allow development

Question 18

How are human embryonic stem cells (ESCs) different from mouse ESCs?

Answer 18

Human ESCs are ‘primed’ pluripotent cells; mouse ESCs are ‘naive’ pluripotent cells

Question 19

What are organoids?

Answer 19

3D mini-organs that recapitulate aspects of organ development

Question 20

How are cerebral organoids developed?

Answer 20

1. Grow human pluripotent stem cells
2. Form embryoid bodies
3. Culture in Matrigel
4. Transfer to spinning bioreactor

Question 21

List some applications of embryonic stem cells.

Answer 21

• Disease modeling
• High-throughput drug screening
• Understanding human-specific development
• Modeling neurodegenerative diseases
• Studying developmental origins of cancer

Question 22

What are some limitations of embryonic stem cells?

Answer 22

• Immunogenic if used for transplantation
• Ethical concerns related to human embryonic tissue
• Technical challenges in creating fully functional tissues
• Variability between organoid batches