Lecture 2: Stem Cells

Question 1

Mention the two defining attributes of a stem cell.

Answer 1

1. Asymmetric division: the ability to differentiate into many different cell types
2. Self-renewal: the capacity to maintain SC population

Question 2

_______________ are found only in early embryonic tissues and derive from the first few cell divisions after fertilisation.

Answer 2

Totipotent stem cells

Question 3

Recall the range commitment options available to a cell.

Answer 3

Question 4

_________________ is the latest developmental stage harboring pluripotent stem cells.

Answer 4

Blastocyst

Question 5

Mention the changes that occurs during gastrulation.

Answer 5

• Formation of primitive streak: defining all major body axis
• Formation of the three germ layers: ectoderm, mesoderm, endoderm
• Giving rise to distinct tissues in adult

Question 6

Describe the fate of the three type of cells.

Answer 6

Question 7

____________________ is isolated immediately following birth and has some pluripotent characteristics.

Answer 7

Placenta stem cells

Question 8

Compare between adult and embryonic stem cells

Answer 8

Question 9

What is a ‘stem cell niche’?

Answer 9

Stem cells exist in a microenvironment supporting their maintenance and normal function.

Examples such as the follicle bulge (reserve of skin stem cells), Paneth cells, and Neural Stem Cells in the subventricular zone.

Question 10

The activation of adult stem cells can be _____ or ___________.

Answer 10

local, systemic

Question 11

Explain stem cell mobilisation in the case of AMI.

Answer 11

In acute myocardial infarction, the ischemic injury caused to the myocardiocytes causes the release of chemokines, which mobilise quiescent stem cells from the bone marrow into the peripheral circulation.

Question 12

How is stem cell activation analysed in the case of brain injury?

Answer 12

Nestin is a protein marker used to mark progenitor/stem cells. After brain injury, cell imaging would should higher readings of nestin.

Question 13

Explain the mechanism of SC activation in liver injury.

Answer 13

When hepatocytes die, it releases signals which activated both the Kupffer and Hepatic Stellar Cells. Activated KC releases cytokines promoting proliferation (PDGF, TNF), contraction (ET-1), fibrogenesis (TGF-b), and chemotaxis (PDGF).

The activated stellate cell is characterized by proliferation, contractility, and chemotaxis. This state of the stellate cell is the main source of extracellular matrix production in liver injury.

Question 14

What is the hematopoietic system?

Answer 14

The haematopoetic system is the system in the body involved in the creation of the cells of the blood.

Question 15

Lymphocytes originate from __________ which differentiate into ______________.

Answer 15

Hematopoetic Stem Cell (HSC), Early Progenitor with Lymphoid Potential

Question 16

Explain the mechanism of SCNT.

Answer 16

Somatic Cell Nuclear Transfer

It is a form of asexual reproduction, where no sperm is involved. Nucleus form the patient cell is transferred into a donor egg (nucleus removed). It requires an electric or chemical stimulus to begin dividing. It is functionally different from a regular fertilised egg.

Question 17

Describe briefly iPS.

Answer 17

Induced pluripotent stem cells are a type of pluripotent stem cell that can be generated directly from a somatic cell. Pluripotent stem cells hold promise in the field of regenerative medicine. Because they can propagate indefinitely, as well as give rise to every other cell type in the body (such as neurons, heart, pancreatic, and liver cells)ly from a somatic cell.

Question 18

Mention the advantage and disadvantage of the various types of stem cells.

Answer 18

Question 19

Describe briefly about cancer stem cells.

Answer 19

It has limitless replicative potential. It may arise through the transformation of a normal stem cell or through acquired genetic lesions that impart a stem-like state or a more mature cell.

Question 20

Define pluripotency.

Answer 20

It refers to a stem cell that has the potential to differentiate into any of the three germ layers: endoderm (interior stomach lining, gastrointestinal tract, the lungs), mesoderm (muscle, bone, blood, urogenital), or ectoderm (epidermal tissues and nervous system), but not into extra-embryonic tissues like the placenta.

Question 21

Define multipotency.

Answer 21

Multipotency describes progenitor cells which have the gene activation potential to differentiate into discrete cell types.

Question 22

Define oligopotency and unipotency.

Answer 22

Oligopotency is the ability of progenitor cells to differentiate into a few cell types.

Unipotent cell is the concept that one stem cell has the capacity to differentiate into only one cell type.