Question

1- Out of all the potential therapeutic usages of pluripotent stem cells (ESCs and iPSCs only), which one do you think are they MOST promising for? Explain your answer.

2- Both embryonic germ cells and embryonic stem cells are pluripotent cells. They also both express SSEA-1 and TNAP. If you had two culture flasks with cells, one cell type in each and you had forgotten to label your culture flask with the name of the cell line, what could you do to figure out which one is which (i.e. what assay would you perform in the lab) (1 pt)?

3- The intestinal stem cell sits exactly at position 4 in the crypt.

A- What experiment using a DNA analog was performed to find out it is the stem cell? Name AND describe the experiment.

B- At that position, what keeps it from differentiating into a transit amplifying cell?

4- A cell population that you are growing in a culture dish expresses Nanog. However, when cells differentiate into endoderm, Nanog is also expressed in early endoderm cells. How do you make sure the cells in your culture dish are pluripotent stem cells, not endodermal cells?

5- Embryonic stem cells are anchorage dependent cells. What happens when they are placed into specially treated culture plates to which they cannot adhere?

Answer 1

1) Out of ESCs and iPSCs, iPSCs are most promising embryonic stem cells.

Explanation: Because ESCs are derived from the inner cell mass, but there exists several constraints for the use of ESCs. Immune compatibility between the donor and recipient is the one constraint that results in rejection of transplanted cells. The other one is ethical problem because ESCs isolation causes death of embryo. To avoid these two constraints iPSCs are used. iPSCs are derived from the somatic cells using set of factors such as Oct4, Sox2, KLF4 and c-Myc. Thus, iPSCs use avoids the two constraints immune compatibility and ethical problem of ESCs.

2) Differential gene expression analysis will be performed.

3) a) Cell tracking assay will be performed.  thymine analogs 5-bromo-2′-deoxyuridine (BrdU) and 5-iodo-2′-deoxyuridine (IdU) will be used for tracking proliferative cells.  BrdU and IdU will be incorporated in newly synthesized DNA.

b) located within the crypts