introduction

Question 1

What determines stem cell’s potency?

Answer 1

The number of lineages a stem cell gives rise to determines its potency. The stem cell in the drawing gives rise to two lineages (blue and green) → it is bipotent

Question 2

What is the main difference between a stem cell and a normal cell?

Answer 2

Very important different between the stem cell and its progenitor cells; STEM CELLS CAN GIVE RISE TO OTHER STEM CELLS (SELF RENEWAL). Progenitors can proliferate but can only proliferate a given number of cells

Question 3

When does the most amplification happen?

Answer 3

Progenitors are usually the step where most of the amplification happens. We get many more cells

Question 4

What is a lineage commitment and what processes take place during?

Answer 4

Lineage commitment – progenitor cell needs to decide whether to commit to the blue lineage or to green lineage. During lineage commitment proliferation still takes place but differentiation is much more prominent

Question 5

What is the benefit of having progenitor cells and not going straight from the stem cell to the differentiated cells?

Answer 5

• more control over what we produce - sometimes one lineage is more needed than the other so its better when they don’t just come from the stem cell and we can actually regulate what we get
• having fewer stem cells is more energetically reasonable. Organisms use a lot of energy to keep the stem cell in their stem cells stage so having fewer oof them is energetically more efficient. Therefore pushing the amplification function on the progenitors is beneficial
• progenitors give us much more amplification than just going from a stem cell would

Question 6

Why is having clones beneficial?

Answer 6

clones- groups of cells that are identical; having groups of clones within the tissue is beneficial. In case something goes wring we always have a backup

Question 7

What is clonal hematopoesis?

Answer 7

Clonal hematopoesis – if you have few stem cells your blood is genetically very similar, usually happens in the old age but if young people have it they have a much higher chance of developing leukemia

Question 8

What are markers used for?

Answer 8

Markers are used to differentiate cells from each other

Question 9

What is a differentiated cell?

Answer 9

Differentiated cell- a cell with a specified function. Most differentiated cells are post-mitotic. Differentiation happens by steps and is usually preceded by cell division. Cells don’t change rapidly. It’s not a switch like behaviour. They change a little but every time and only by comparing them over long periods you can actually see the changes.

Question 10

What is a lineage?

Answer 10

Lineage - the genealogic pedigree of cells related through the cell division. Cells of the same lineage may derive from a common progenitor cell or cell population. Lineages can start at different stages of embryonic development.

Question 11

What is a clone?

Answer 11

Clone the progeny of a single cell. It can contain multiple lineages or not. Clonal analysis is used experimentally to determine the relationship betweeen lineages. All cells in a clone are genetically identical.

Question 12

What is self renewal?

Answer 12

Self renewal - mitosis that leads to at least one daughter cell identical to the mother cell. Stem cells self renew because they give rise to more stem cells. Their progeny loses the ability to self-renew. Loss of self-renewal can happen gradually. Historically stem cells were thought to have infinite self-renewal ability, however only ES cells truly do. However stem cells spend a lot of time in the quiescent phase so they might not produce anything for quite some time.

Question 13

What is the difference between regular cell division and self renewal?

Answer 13

Self renewal contrary to regular cell division is specific to stem cells and is “infinite”. Progenitors of stem cells might divide although they don’t have to and the number of divisions is usually predefined.

Question 14

What is lineage commitment?

Answer 14

Lineage commitment - restricted ability to give rise to a specific set of differentiated cells. It is usually a one way process, once you commit there is no coming back.

Question 15

What is Ki-67?

Answer 15

Ki-67 - an intracellular marker that marks cells that are currently actively going through the cell cycle

Question 16

What is SSEA?

Answer 16

SSEA - used for human embryonic stem cells

Question 17

What is Oct4?

Answer 17

Oct4 - the marker of totipotency, is a transcription factor that is responsible for expression of many genes

Question 18

What are progenitors/amplyfing stem cells?

Answer 18

Progenitors and transit amplifying cells - intermediate, often unipotent and highly proliferative cells, located between stem cells and differentiated cells within a certain lineage. Sometimes easily distinguishable though markers, sometimes distinguishable only prospectively through functional assyas

Question 19

What are stem cells?

Answer 19

Stem cells are cells with ability to give rise to more of themselves and to a different progeny

Question 20

Do different stem cells have common morphology?

Answer 20

do not have specified morphology, there have beeen attempts to compare stem cells from different tissues but apart from being small with a large nucleus and small cytoplasm they don’r have that much in common

Question 21

What are some characteristics of stem cells?

Answer 21

• maintain tissues turnover through our lifetime
• generate differentiated progeny
• re-generate themselves - self renewal
• tend to be quiescent

Question 22

What are primary cells?

Answer 22

Straight from animals/donors/patients

Question 23

Why do we like primary cells?

Answer 23

we tend to like primary cells because they are what the tissue is just taken out of it

Question 24

Why are primary cells difficult to work with?

Answer 24

• primary cells tend to die a lot because they go through a lot of stress during the extraction from the organnism
• making the primary cels happy in their new environment is quite tricky as they are used to having all the input from their surrounding like signals from the tissue and the structure of the 3D matrix but more is becoming possible due to advances in bioengineering

Question 25

What are cell lines?

Answer 25

Cells derived from animal/human cells following extensive culture

Question 26

Why working with cell lines might be easier?

Answer 26

standardised through international providers

Question 27

Why can cell lines be inaccurate?

Answer 27

have accumulated transforming mutations to allow them to survive many passages; however because of the

Question 28

What is meant by potency?

Answer 28

Potency - ability to give rise to multiple lieages

Question 29

What molecules usually serve as stem cell markers?

Answer 29

Lineage and stem cell markers -cell surface proteins, antigens, molecules or functions used to distinguish cells of different lineages or stem, progenitors and differentiated cells. Markers can be almost anything but cell surface receptors are preferred as they can be easily targeted with antibodies.