Stem Cells

Question 1

What is a stem cell?

Answer 1

a primitive cell that is self renewing and can give rise to more specialized cells

Question 2

What are some characteristics of stem cells? (4)

Answer 2

not terminally differentiated, divide without limit, undergo slow division and when they divide one cell remains a stem cell while the other is differentiated.

Question 3

What is the difference between adult stem cell and embryonic stem cells?

Answer 3

Adult cells are tissue specific and cannot give rise to any kind of cell while embryonic cells can

Question 4

What is a stem cells potency?

Answer 4

How well the cell can proliferate. How many cells types the cell is able to give rise to

Question 5

What is totipotency and what is an example of a cell that exhibits this?

Answer 5

Ability to give rise to all cells of an organism- including embryonic and extraembryonic tissues- ex is a zygote

Question 6

What is pluripotency and give an example

Answer 6

Ability to give rise to all cells of the embryo and subsequent adult tissues. Ex is embryonic cells

Question 7

What is multipotency and give an example

Answer 7

Ability to give rise to different cell types of a given lineage. Ex is adult stem cells like hematopoetic becoming WBCs

Question 8

What are founder stem cells?

Answer 8

Cells destined to be stem cells but have fixed number of divisions- each tissue has set of founder cells that are determined early in development

Question 9

What are transit amplifying cells?

Answer 9

Cells that divide frequently in a tissue. Have some stem cell qualities but have finite divisions- They are also committed to one cell type

Question 10

What is divisional asymmetry?

Answer 10

a method of stem cell maintenance that dictates that when stem cells divide, one cell will remain a stem cell while the other will differentiate into appropriate cell type- Achieved through internal stimuli

Question 11

What is Environmental asymmetry?

Answer 11

A method of stem cell maintenance that dictates that division will make two identical cell types but one differentiates based off environmental factors

Question 12

What is the immortal Strand hypothesis?

Answer 12

States that in newly dividing cells, them stem cell will always get the original DNA strand and the daughter cell will retain the newly synthesized DNA

Question 13

What are embryonic stem cells?

Answer 13

Cells derived from the blastocyst that are capable of proliferating indefinitely into any cell type.

Question 14

What is a tertomas and how can they occur?

Answer 14

Tumors of cells that are not where they are suppose to be. They can be the result of ES cells being introduced back into blastocyst at too late of a stage

Question 15

How do we generate human ES cells?

Answer 15

A serum containing cells and fibroblast feeder cells are placed in a petridish. Cells will separate and grow indefinitely on the medium

Question 16

How are different cell types induced from ES cells?

Answer 16

They respond to given signals from the body such as retinoic acid

Question 17

What are the genes associated with ES cells?

Answer 17

Transcription factors like Nanog, Oct4, Sox2 and FoxD3 are seen commonly in stem cells and when these genes are knocked out, cells will not differentiate well.

Question 18

What are adult stem cells?

Answer 18

Cells Found in tissue that are limited in their potential for differentiation by molecular restraints on gene expression. Responds to demands of growth/repair

Question 19

What is cord blood?

Answer 19

Cells that are harvested at birth from the umbilical cord. Can be stored and used later for specific therapies. These are undifferentiated cells so exhibit pluripotency

Question 20

What is the success of ES cell therapy?

Answer 20

It is reliable and gives highly reproducible results. They are able to induce development of specialized cell types and solve problems of organ rejection

Question 21

What are some of the limitations using adults stem cells as a method of treatment?

Answer 21

They have restricted capacity and growth potential

Question 22

What are hematopoietic cells and how do they differ from stromal stem cells?

Answer 22

both come from the bone marrow but give rise to different tissue types- Hemato give rise to blood components while stromal are connective tissues

Question 23

What are some therapies using adult stem cells?

Answer 23

neuro regeneration- obtain cells from bone marrow or adipose and differentiate them to the neuronal like cells

Question 24

What are some challenges for regenerative medicine?

Answer 24

There is always chance of rejection by the host that the cells are injected into. it is also very difficult to get a sufficient amount of cells for studying and implantation.

Question 25

What are the two sources for generating human ES cells?

Answer 25

Induced pluripotent stem cells or somatic cell nuclear transfer

Question 26

What are iPS cells?

Answer 26

It involves taking human cells, reprogramming them using the transcription factors for stem cells and generating patient specific pluripotent cells.

Question 27

What are some limitations to iPS?

Answer 27

There is the potential of teratomas forming at the site that these cells are introduced.

Question 28

What is somatic cell nuclear transfer?

Answer 28

A denucleated egg cell is fused with an adult somatic cell. This cell is then stimulated to go through division and begins to divide as it were a fertilized egg.

Question 29

What are some limitations to SCNT?

Answer 29

There are moral dilemmas with “creating life”. There are also challenges like inefficiency since hundreds of cells needed, where do the oocytes come from and would need to be available in all hospitals.