lecture 1 theme B

Question 1

What stage does the blastocyst appear during development?

Answer 1

blastocyst starts at the 16 - 32 cell stage

Question 2

What does the inner cell mass form?

Answer 2

Inner cell mass becomes the 3 germ layers; endo, ecto, and mesoderm

Question 3

What structures does the trophoblast form?

Answer 3

Trophoblast becomes the embryonic tissues and membranes (eg placenta)

Question 4

What germ layer are cardiac myocytes formed from?

Answer 4

mesoderm

Question 5

What does the heart’s development look like?

Answer 5

heart was initially a tube then it folds in on itself to form the 4 chambered structure.

Question 6

What are the 2 ‘pools’ of cardiac progenitor cells?

Answer 6

primary heart field (cardiac crescent, left ventricle, atria)

secondary heart field (right ventricle and outflow tract)

Question 7

How is development of cardiac cells guided?

Answer 7

via cardiac-restricted transcription factors such as GATA4, Nkx2.5, MEF2C

Question 8

How does the heart grow during lifetime?

Answer 8

proliferation mostly occurs during development.

Hypertrophy occurs after birth. Cardiac myocytes exit cell cycle at birth.

Question 9

What happens during lifetime to myocyte number in heart cells?

Answer 9

Heart cell number decreases over time. Number of cells is modified directly after birth via apoptosis and differentiation. This number typically grows until a few months after birth then starts to decrease.

Question 10

What is the turnover rate of heart cells?

Answer 10

1%/year

Question 11

What is a process that is being developed to counteract the decrease in cardiac myocyte numbers?

Answer 11

stem cell research has been taking place

Question 12

What happens during a myocardial infarction?

Answer 12

70 - 90% of cases are due to rupture of atherosclerotic plaque followed by thrombosis.

Result is irreversible cell death. These cells are replaced with connective tissue.

Question 13

How fast does a myocardial infarction cause death of cardiac myocytes?

Answer 13

25% in a few hours.

The dead cells are not easily replenished due to low rate of production of cardiac muscle cells.

Question 14

What happens during heart failure (progressive)?

Answer 14

Severe deficiency in ventricular pump function due to factors such as cardiac hypertrophy and myocardial infarction.

Question 15

How did skeletal myoblast infusion work for the heart?

Answer 15

skeletal muscle myoblasts worked well in increasing the ejection fraction. However they didn’t conduct as well as cardiac myocytes. As a result there are risks of arrhythmia.

Question 16

What are the features of a stem cell?

Answer 16

self- renewal

undifferentiate

Question 17

What happens to embryonic stem cells over time?

Answer 17

They progressively develop specialist characteristics: toti->pluri->multi potent -> then to fully differentiated somatic cells.

Question 18

What has stem cell research allowed scientists to do to somatic cells?

Answer 18

Adult somatic differentiated cells can be induced to reverse specialisation to pluripotency.

Question 19

What stages of embryogenesis contain the different kinds of stem cells?

Answer 19

before formation of the blastula stem cells are totipotent.

Cells of the inner cell mass are pluripotent. (blastocyst)

As cells are forming they become multipotent stem cells. (Gastrulation and organogenesis)

Question 20

What are the tissues that form from mesenchymal progenitor cells?

Answer 20

Bone

muscle

adipocytes

Question 21

What are the tissues that form from hemopoietic progenitor cells?

Answer 21

Blood cells

Question 22

What are the types of adult stem cells and where can they be found?

Answer 22

stem cells in adults exist in tissue that undergo renewal and repair. potential autologous source of cells

adult bone marrow have several cell populations. (heterogenous in nature consisting of mesenchymal and hematopoietic stem cells. (These have bee most thoroughly investigated)

Endothelial progenitor cells are bone-marrow derived stem cells obtained from peripheral circulation.

Several cardiac progenitor cell populations have been identified.

Question 23

How are embryonic stem cells obtained?

Answer 23

destruction of an embryo

therapeutic cloning

nuclear reprogramming (using transcription factors to create them)

Question 24

How are adult stem cells obtained?

Answer 24

bone marrow aspiration and cell fractionation for hemopoeitic cells and mesenchymal cells.

Induced pluripotent cells are obtained via a skin biopsy which is reprogrammed

Question 25

How do researchers identify stem cells?

Answer 25

Researchers use specific immunological markers to identify certain stem cells.

Question 26

What are the methods of stem cell administration to the heart?

Answer 26

Intracoronary arterial route

Intraventricular route

Question 27

What are the advantages and disadvantages of the intracoronary injection of stem cells?

Answer 27

Advantage: Cells travel to regions where oxygen and nutrient supply is preserved.

Disadvantage: Homing of stem cells requires migration out of the vessel and into the muscle

Question 28

What are the advantages and disadvantages of the intraventricular route?

Answer 28

Advantage: Not limited by cell uptake or embolic risk.

Disadvantage: Risk of ventricular perforation and cell death (due to injection)