Stem Cells Flashcards
What is the definition of a stem cell?
- Able to self renew
2. Able to differentiate into specialised cells
What is cell differentiation?
- Tightly controlled process
* Driven by changes in gene expression
What are the different types of differentiation capability?
Totipotent Pluripotent Multipotent Bipotent Unipotent
What is embryology?
1) Fertilisation
2) Cleavage
3) Blastocyst formation
4) Gastrulation
5) Organogenesis
What is the structure of an embryonic stem cell?
1) Primitive streak
2) Ectoderm
3) Mesoderm
4) Endoderm
What are tissue stem cells?
- Occur in many tissues including: bone marrow, adipose tissue, dental pulp, epithelia, nervous tissue etc.
- Partially differentiated
- Live in a stem cell niche
Where are Hematopoietic stem cell (HSC) found?
in vascular niche surrounded by mesenchymal stromal cells derived from Mesenchymal Stem Cells
What are mesenchymal stem cells?
MSCs = example of tissue stem cells
They are multipotent
They make the different specialized cells found in the skeletal tissues
MSCs can make fat, cartilage and bone cells. Some evidence of differentiating to other lineages (eg. nerve cells)
What does multipotent mean?
they can produce more than one type of specialized cell of the body, but not all types.
What is the mesenchymal stem cells differentiation?
Adipogenic
Osteogenic
Chondrogenic
What are haematopoietic stem cells?
HSCs
• Collected via peripheral blood stem cell collection or Bone marrow donation
In haematopoiesis, what do Multipotential haematopoietic stem cells (haemocytoblasts) differentiate into?
> common myeloid progenitor
>common lymphoid progenitor
In haematopoiesis, what do common myeloid progenitors differentiate into?
> megakaryocyte
erythrocyte
mast cell
myeloblast
In haematopoiesis, what do megakaryocytes differentiate into?
> thrombocytes
In haematopoiesis, what do myeloblasts differentiate into?
> basophil
neutrophil
eosinophil
monocyte
In haematopoiesis, what do monocytes differentiate into?
> macrophage
In haematopoiesis, what do common lymphoid progenitors differentiate into?
> natural killer cell (large granular lymphocyte)
> small lymphocyte
In haematopoiesis, what do small lymphocytes differentiate into?
> T lymphocyte
> B lymphocyte
In haematopoiesis, what do B lymphocytes differentiate into?
> plasma cell
How does the differentiation ability of embryonic stem cells and tissue stem cells compare?
ESC: pluripotent
TSC: multipotent
What is pluripotent?
capable of becoming any cell in the human body except cells needed to support the embryo, such as the placenta
How does the role in body of embryonic stem cells and tissue stem cells compare?
ESC: to develop embryo into an entire human
TSC: to replace cells in the body which die throughout life due to wear and tear or injury and disease
How does the sources for research of embryonic stem cells and tissue stem cells compare?
ESC: unused IVF embryos which have been donated or embryos created for the purpose from donated eggs and sperms
TSC: mature adult tissues such as bone marrow, muscles and skin: and from the fetus, umbilical cord, placenta and amniotic fluid.
How does the advantages in research and therapy development of embryonic stem cells and tissue stem cells compare?
ESC: have a strong ability to self renew in the lab = constant supple of ESCs
pluripotency =ES cells have potential to produce any cell type in the body
TSC: if taken from the patient’s own body for used in therapies, cells would be genetically identical to that of the patient, avoiding problem of immune rejection
There are less ethical considerations compared with ESCs
How does the disadvantages in research and therapy development of embryonic stem cells and tissue stem cells compare?
ESC: genetically different to cells of potential patients = immune rejection
ethical issues over embryo destruction
TSC: they usually only produce a limited number of different cell types
Conditions supporting self-renewal in the lab have only been identified for a few tissue stem cell types (skin and cornea)
are found in small numbers and are difficult to isolate
What are induced pluripotent stem cells (iPSCs)?
- Induced pluripotent stem cells
- First discovered 2006
- Re-programmed skin cells
- Gene transfection (using viruses)
- 4 genes: C-Myc, Klf4, Oct4 and Sox
- More recently protein based reprogramming
- Safety concerns