9b.2 Stem Cells and Tissue Engineering

Question 1

Repopulation Assay: Bone Marrow (BM) Transplant Stem Cells

Answer 1

• UV a mouse to destroy it’s BM cells
• if left alone it’ll die
• inject with normal BM cells
• it survives
• isolate the hematopoietic stem cells

Question 2

Hematopoieitc Stem Cells have 2 options

Answer 2

Lymphoid progenitor cells:

• T lymphocyte
• B lymphocyte

Myeloid Progenitor cell

• RBC
• Platlets

Question 3

In Vitro Induction Assays using Stem Cells

Answer 3

• inducers are ligands
• can figure out potency of cell population (number of fates cell can take up)
• induce cells and wait to see what fates they take.

Question 4

Hair Follicle and Nude Mice

Answer 4

•Hair Follicle has bulge cells (Stem cells).
• Bulge cells are in contact with dermal papilla, present at the base of the follicle.
•length of hair is time it spends in anlagen phase
•Bulge cells have 3 types of SC pattern
1)hair follicle SC (hair growth and maintenance)
2) melanocyte SC (colour)

Question 5

3 Hair growth phases

Answer 5

• anagen: in growth
• catagen: regression phase
• telogen: rest phase

Question 6

bulge cells (tagged with GFP) were isolated and transplanted into nude mice (no hair)

Answer 6

• When bulge cells (tagged with GFP) were isolated and transplanted into nude mice (no hair), tufts of hair formed.
• Bulge cells in contact with the Dermal Pappili cells induce Wnt signalling that leads to hair growth.
• Bulge cells move away and the cells become quiescent.
• nude mice have weak immune system so no hair
• when dermal papilla in close contact with bulge, hair length increases.

Question 7

repair and tissue repair Problems

Answer 7

1. Ethical

2. Non-autologous, rejection of donor cells by host.

Question 8

Embryonic Stem Cells (ESC)/ germ cells (EGC)

Answer 8

ESC- cultured from inner cell mass of early embryo. highly potent

EGC- derived from primordial germ cells that have not yet reached the gonads

Question 9

Formation of ICM Cells

Answer 9

Trophectoderm undergoes asymmetrical division perpendicular to apicobasal axis (instead on the normal symmetrical division to expands the trophectoderm)
This creates an ICM (inner cell mass)

Question 10

Stem Cells Culture

• Culture ES cell in retinoid acid
• Culture ES in Fgf and platelet dervied growth factor

Answer 10

The differentiation of embryonic stem cells into lineage restricted stem cells can be accomplished by altering the medium in which the ES grows.

• Culture ES cell in retinoid acid
• functional Glial stem cells
• Culture ES in Fgf and platelet dervied growth factor
• Functional neurons

Question 11

ESC is what kind of stem cell?

Answer 11

pluripotent, one cell is capable of developing into the entire embryo

Question 12

Can cell differentiation be reversed ?

Answer 12

-Uv irradiated on host egg
-enucleated egg
-remove skin cells from frog and isolate nucleus
-inject donor nucleus into host inculcated egg
-blasula
-tadpole
adult

Question 13

Dolly the sheep

Answer 13

-Enucleated egg cells fused with cells derived from mammary gland (epithelial cells) -Reduced serum levels caused epithelial cells to enter quiescent state (G0) (via starvation) that “unmasked” unexpressed genes -Fused cells “activated” by brief electric pulse. -Egg implanted in surrogate sheep -Dolly proved that even cell has all the genetic material needed. -enuclulatted = cell with nucleus removed -Dolly’s Death: due to telomers. from 6 years old cell she already had shorter tellers and so that probably set her up for a faster death. A somatic cell is a regular body cell, not an egg cell. The nucleus of the somatic cell was removed and put into an unfertilised egg cell. The process is called somatic cell nuclear transfer. The cell used as the donor for the cloning of Nam was taken from a mammary gland. The production of a healthy clone therefore proved that a cell taken from a specific part of the body could recreate a whole individual. She was cloned so she did not need any male cells to fertilize the egg and mature it. She only has one parent.

Question 14

Reprogramming of somatic cells induced pluripotent stem (iPS) cell

Answer 14

•EScells can be differentiated in somatic cells then reprogrammed to induced pluripotent sen cell by TF such as Sox2 and Oct4
•Regenerative Medicine:
Disease treatment
Organ repair

Question 15

iPS derived HSC correct sickle cell anemia

Answer 15

1) harvest tail tip fibroblasts
2) infect with Oct 4, Sox2
3) correct sickle cell mutation in iPS cells by specific gene targeting
4) differentiate into embryo bodies
5) transplant corrected hematopoietic progenitors back into irradiated mice

Question 16

Regenerative Medicine

Answer 16

• Modifications of culture techniques made it possible for gene expression of iPS
cells to become identical to that of mouse embryonic stem cells.
• Entire moues embryos could be isolated from a single iPS cell.
• Importance lies on the ability of iPS cells to repair damaged organs.
• Field of therapy called regenerative medicine.

Question 17

Natural Stem cell therapy: Trafficking cells from Fetus across placenta Stem Cells

Answer 17

• embryo to maternal circulation to moms heart which was experimentally damaged
• generated diverse cardiac lineages

Question 18

Mesenchymal Stem Cells

Answer 18

if cells sit on colagen coat thats similar elasticity to brain then MSC differentiated into cells with neural markers but not mucle or bone markers. gel stiffer, cells hsve muscle markers.