Lecture 27: Stem cells Flashcards
What are stem cells?
- Unspecialised cells capable of renewal by cell division.
- Can be induced to become tissue specific mature cells with special functions
What are the different types of potency?
Totipotent -> Embryonic tissues
Pluripotent - Any cell (Embryonic stem cells)
Multipotent (i.e heamopoetic stem cells) and unipotent-single lineage i.e skin (adult stem cells)
What are some examples of multipotent stem cells?
Mesenchymal stem cells i.e found in bone marrow.
Can turn into; Adipocytes, cartilage, bone, tendons, muscle and skin
Release; Anti-inflam and immomudulatory factors
Do all organs have stem cells?
No ie kidneys do not, nor heart
Found in
- Brain
- Blood
- Muscle
- Gut
- Skin
What are some examples of adult stem cell therapies?
Blood stem cell transplants Skin grafts (have stem cells) Corneal transplants (have stem cells)
What are pluripotent stem cells?
Self renewing cells that are capable of differentiating into any tissue
What are some examples of pluripotent stem cells?
Embryonic stem cells
Induced pluripotent stem cells (iPSCs)
In an embryo where are the pluripotent cells found?
In the inner cell mass of the blastocyst prior to gastrulation (formation of three germ layers that each give rise to a limited number of tissue types, reduced potency)
How was the potency of ICM cells tested?
ICM cells were taken from the embryo of a black mouse and injected into the blastocyst of a brown mouse. The embryo was then placed back in a black mouse and the baby was chimera.
What are some notes on ES cells?
- Can be maintained indefinitely in cell culture
- Cant perform blastocyst injections with hES cells.
Why does the blastocyst in which ICM cells are injected into accept the ICM cells?
The blastocyst host cells are tetraploid and contribute only to the placental tissues
The injected ICM / ES give rise to the embryo
What is a teratoma assay?
Injecting Stem cells into any tissue i.e not embryonic and watching the formation of a teratoma over time consisting of the different formed germ line cells
What is an embryoid body assay? // not sure what the learning point of…
Cultured ES cells are exposed to differentiation media and three germ tissues can be detected i.e
What is the potential of ES cells?
- Tissue engineering
- Cell based therapies
- Disease in a dish models
What is the challenge to overcome with ES cells?
- Teratoma
- Purity of cells
- Ethical concerns
- Immunologically privileged sites = brain and spinal cord, eye, testes i.e rejection is a concern
What is cloning?
Somatic cell nuclear transfer
i.e put DNA in a terminally differentiated nucleus, can form ES cells also babies….
Describe induced pluripotent stem cells;
Somatic cell nucleus is obtained and placed in an enucleated egg or oocyte. It is then exposed to reprogramming factors and reprogrammed to embryonic state. = iPSC
What are the reprogramming factors for creating iPCS?
Oct4
SOX2
Klf4
cMYC
What are the benefits of iPSC?
- No immune rejection if cells are reprogrammed from patient
- No moral objections b/c no embryo
- BUT teratoma risk remains, purity…
What method can be used for gene editing of iPS cells?
CRISPR = efficient and fast
i.e sickle cell anemia…
What is another use of iPS cells?
Using IPS cells to grow human organs in animals
or
developing organoids i.e disease in a dish
