Stem cell technology Flashcards
What are stem cells
Cells that have the capacity to develop into a variety of cell and tissue types in response to specific environments.
Hallmarks of stem cells
Self-renewal
Potency
Two types of stem cells gotten from embryos
Embryonic stem cells [ES cells])
Primordial germ cells (embryonic germ cells)
Embryonic stem cells
Found in the inner cell mass of blastocyst. Can give rise to any tissue type in the body depending on its microenvironment
Primordial germ cells
Stem cells that are only capable of giving rise to the male and female gametes (germline stem cells)
Sources of adult stem cells
bone marrow, skeletal muscle, brain tissue, skin and fat.
Molecular mechanism of stem cell differentiation
The stem cell gene codes for an mRNA which creates a transcription factor which is capable of turning on multiple genes, depending on the cell’s microenvironment
What are the 3 main types of stem cells
embryonic stem cells
adult stem cells
induced pluripotent stem cells
Embryonic stem cells
Pluripotent cells of the inner mass of the blastocyst of an embryo. These cells supply new cells for an embryo, as it grows and develops into a baby.
Pluripotency
The ability to change into any cell in the body
Adult stem cells
Adult stem cells supply new cells as an organism grows and to replace cells that get damaged.
They are said to be multipotent. e.g Haematopoietic stem cells can only replacr the various types of cells in the blood
Multipotency
The ability to be able to change into just some cells of the body’s tissues
Induced pluripotent stem cells
Has properties similar to embryonic stem cells. They are engineered by manipulating the expression of certain genes, thereby ‘reprogramming‘ somatic cells back to a pluripotent state using protein transcription factors, Oct4, Sox2, Klf4 and c-Myc.
One function of the four transcription factors used in generating iPSCs
Oct4, and Sox2 are pluripotency master genes.
c-Myc, gene is known to increase proliferation rate.
Klf4 leads to increase in p21 levels resulting in proliferation suppression, on one hand and then reduces the cellular levels of p53, which has appositive effect on the reduction of the apoptosis risk.
Method of creating iPSCs
adult cells are grown in cell culture.
specific combinations of regulatory genes are inserted into retroviruses (viruses that convert RNA [ribonucleic acid] into DNA), which are then introduced to the culture medium.
The retroviruses transport the RNA of the regulatory genes into the nuclei of the adult cells, where the genes are then incorporated into the DNA of the cells.