History edit
There is a debate as to whether the Greeks were the first to realize the existence of stem cells. This debate is based around the story of Prometheus - as a punishment for giving fire to mankind, Zeus ordered Prometheus to be chained to a rock and sent an eagle to eat parts of his liver every day. However, Prometheus do not die because his liver is regenerated daily, but only for it to be eaten again.
Stem cell research came into prominence after the Second World War, when many people were ill from radiation poisoning; stem cells were shown to be able to rescue some of these patients. It can now also be used after radiotherapy, where ionizing radiation is used to kill the cancer cells. But this also means healthy cells are killed also; stem cells are introduced to replenish the healthy cells. Nuclear transfer experiment (the transfer of nucleus from one cell into another) is the basis of most cloning techniques. It was first proposed by Spemann in 1938[1], and the first ever successful nuclear transfer was done in Rana pipiens by Robert Briggs and Thomas King in 1952.[2] The process involves the removal of genetic materials from the nucleus of a somatic cell with the desired genes, and injecting it into an egg cell in which the nuclear contents are removed. The resulting cell is stimulated by an shock to initiate division.
In 1964, scientists isolated a single type of stem cell from teratocarcinoma (a germline tumour) and named it embryonic carcinoma (EC) cells. EC cells occasionally occurs in a gonad (ovaries or testes) of a fetus and are usually aneuploid. They are basically stem cells that are malignant. The characteristics of EC cells are also observed when human ES cells are grown in culture; over time, ES cells proliferate faster, are easier to maintain and acquire karyotypic changes that mimics to a change to an EC cell.[3]
In 2006, Takahashi and Yamanaka started with mouse embryonic and adult fibroblast cultures and used factors to 'undifferentiate' the cells back into stem cells.[4][5]
- ^ Spemann, Hans. Embryonic Development and Induction. Hafner Press. ISBN 0028526309.
- ^ Briggs, R.; King, T. J. (May 1952). "Transplantation of Living Nuclei From Blastula Cells into Enucleated Frogs' Eggs". Proceedings of the National Academy of Sciences. 38 (5): 455–463. doi:10.1073/pnas.38.5.455. PMC 1063586. PMID 16589125.
{{cite journal}}: CS1 maint: date and year (link) - ^ Andrews, PW; Matin, MM; Bahrami, AR; Damjanov, I; Gokhale, P; Draper, JS (2005). "Embryonic stem (ES) cells and embryonal carcinoma (EC) cells: Opposite sides of the same coin". Biochemical Society Transactions. 33 (Pt 6): 1526–30. doi:10.1042/BST20051526. PMID 16246161.
- ^ Takahashi, Kazutoshi; Yamanaka, Shinya (2006). "Induction of Pluripotent Stem Cells from Mouse Embryonic and Adult Fibroblast Cultures by Defined Factors". Cell. 126 (4): 663–76. doi:10.1016/j.cell.2006.07.024. PMID 16904174.
- ^ Takahashi, Kazutoshi; Tanabe, Koji; Ohnuki, Mari; Narita, Megumi; Ichisaka, Tomoko; Tomoda, Kiichiro; Yamanaka, Shinya (2007). "Induction of Pluripotent Stem Cells from Adult Human Fibroblasts by Defined Factors". Cell. 131 (5): 861–72. doi:10.1016/j.cell.2007.11.019. PMID 18035408.