3 types of stem cells
- Totipotent
- Pluripotent
- Multipotent
Totipotent
A fertilized egg that has the potential to give rise to all cell types in the body.
Pluripotent
Stem cells that can develop into any cell type in the body except those needed to develop a fetus.
Multipotent
Stem cells that have the ability to differentiate into a limited number of cell types.
When were embryonic stem cells first isolated and cultured in the lab?
1998.
Where were adult stem cells first discovered?
haematopoietic stem cells
discovered in bone marrow in the 1960s.
When were induced pluripotent stem cells (iPS cells) first produced?
Induced pluripotent stem cells (iPS cells) were first produced in 2006 from mouse cells and in 2007 for human cells.
What is the source of embryonic stem (ES) cells?
pre-implant-stage human embryos, usually at the blastocyst stage,
which are initially generated as part of in vitro fertilization procedures but would otherwise be discarded.
How are human ES cells cultured and expanded?
- Recovering of the inner cell mass of the blastocyst through immunosurgery,
- ES cells are cultured under defined conditions that allow them to multiply while remaining undifferentiated.
- Culture vessels often contain irradiated “feeder” cells, such as mouse fibroblasts, to provide a substratum and complex nutrients for ES cell growth.
What are some limitations and challenges associated with ES cells?
- Difficulties in establishing and maintaining cell lines
- Obtaining pure cultures,
- Potential for tumor formation,
- Lack of proper differentiation,
- Genomic instability,
- Immune system rejection
- Ethical considerations surrounding their use.
What is somatic cell nuclear transfer (SCNT) and how is it related to therapeutic cloning?
- Involves taking a donor egg,
- removing its nucleus,
- extracting the nucleus from a skin cell,
- integrating the nucleus into the donor egg.
This technology has been proposed to create new cell lines for research purposes.
What are some problems associated with therapeutic cloning?
- 100% death rate for the embryo,
- Creation of embryos for the purpose of cell harvesting
- Temptation to allow embryos to develop longer to harvest specialized cells,
- The association with human reproductive cloning,
- The likelihood of transplant rejection
- Inefficiency of the process.
Where are adult stem cells found?
- Found among differentiated cells in tissue or organs.
- They reside in various tissues throughout the body.
What is the main physiological role of adult stem cells?
- To maintain and repair the tissue in which they reside.
- They can renew themselves and differentiate to yield the major cell types specific to the tissue.
What are some advantages of using adult stem cells in regenerative medicine?
- Overcoming moral and ethical concerns associated with blastocyst destruction
- Allowing for autologous transplantation
What are induced pluripotent stem cells (iPS cells)?
Induced pluripotent stem cells
- Artificially derived from a non-pluripotent cell, typically an adult somatic cell.
- This is achieved by inducing the expression of specific genes.
How are iPS cells generated?
Introducing certain stem cell-associated genes, such as Oct-3/4 and Sox2, into non-pluripotent cells using viral vectors like retroviruses.
After several weeks, the transfected cells begin to exhibit morphological and biochemical similarities to pluripotent stem cells.
What methods are used to isolate iPS cells?
Isolated through
- morphological selection,
- doubling time
- by using a reporter gene and antibiotic selection.
When were iPS cells first produced from human cells?
2007
