Stem Cells Flashcards
What is a stem cell?
a primitive cell that is self renewing and can give rise to more specialized cells
What are some characteristics of stem cells? (4)
not terminally differentiated, divide without limit, undergo slow division and when they divide one cell remains a stem cell while the other is differentiated.
What is the difference between adult stem cell and embryonic stem cells?
Adult cells are tissue specific and cannot give rise to any kind of cell while embryonic cells can
What is a stem cells potency?
How well the cell can proliferate. How many cells types the cell is able to give rise to
What is totipotency and what is an example of a cell that exhibits this?
Ability to give rise to all cells of an organism- including embryonic and extraembryonic tissues- ex is a zygote
What is pluripotency and give an example
Ability to give rise to all cells of the embryo and subsequent adult tissues. Ex is embryonic cells
What is multipotency and give an example
Ability to give rise to different cell types of a given lineage. Ex is adult stem cells like hematopoetic becoming WBCs
What are founder stem cells?
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
What are transit amplifying cells?
Cells that divide frequently in a tissue. Have some stem cell qualities but have finite divisions- They are also committed to one cell type
What is divisional asymmetry?
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
What is Environmental asymmetry?
A method of stem cell maintenance that dictates that division will make two identical cell types but one differentiates based off environmental factors
What is the immortal Strand hypothesis?
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
What are embryonic stem cells?
Cells derived from the blastocyst that are capable of proliferating indefinitely into any cell type.
What is a tertomas and how can they occur?
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
How do we generate human ES cells?
A serum containing cells and fibroblast feeder cells are placed in a petridish. Cells will separate and grow indefinitely on the medium
How are different cell types induced from ES cells?
They respond to given signals from the body such as retinoic acid
What are the genes associated with ES cells?
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.
What are adult stem cells?
Cells Found in tissue that are limited in their potential for differentiation by molecular restraints on gene expression. Responds to demands of growth/repair
What is cord blood?
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
What is the success of ES cell therapy?
It is reliable and gives highly reproducible results. They are able to induce development of specialized cell types and solve problems of organ rejection
What are some of the limitations using adults stem cells as a method of treatment?
They have restricted capacity and growth potential
What are hematopoietic cells and how do they differ from stromal stem cells?
both come from the bone marrow but give rise to different tissue types- Hemato give rise to blood components while stromal are connective tissues
What are some therapies using adult stem cells?
neuro regeneration- obtain cells from bone marrow or adipose and differentiate them to the neuronal like cells
What are some challenges for regenerative medicine?
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.
What are the two sources for generating human ES cells?
Induced pluripotent stem cells or somatic cell nuclear transfer
What are iPS cells?
It involves taking human cells, reprogramming them using the transcription factors for stem cells and generating patient specific pluripotent cells.
What are some limitations to iPS?
There is the potential of teratomas forming at the site that these cells are introduced.
What is somatic cell nuclear transfer?
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.
What are some limitations to SCNT?
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.
