Chronology of Stem Cells

August 2006

Kazutoshi Takahashi of Department of Stem Cell Biology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan and Shinya Yamanaka from CREST, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan published a paper in the cell journal claiming the induction of Pluripotent stem cell from mouse embryonic and adult fibroblast cultures by defined factors.

They stated that differentiated cells can be reprogrammed to an embryonic-like state by transfer of nuclear contents into oocytes or by fusion with embryonic stem (ES) cells. Little is known about factors that induce this reprogramming. They demonstrated the induction of pluripotent stem cells from mouse embryonic or adult fibroblasts by introducing four factors, Oct3/4, Sox2, c-Myc, and Klf4, under ES cell culture conditions. These cells, which we designated iPS (induced pluripotent stem) cells, exhibit the morphology and growth properties of ES cells and express ES cell marker genes. Subcutaneous transplantation of iPS cells into nude mice resulted in tumors containing a variety of tissues from all three germ layers. Following injection into blastocysts, iPS cells contributed to mouse embryonic development. These data demonstrate that pluripotent stem cells can be directly generated from fibroblast cultures by the addition of only a few defined factors.

This is one cool paper where they have shown the proof that differentiated stem cells can again be reprogrammed into stem cells.

July 19, 2006

President George W. Bush vetoed a bill which would have allowed Federal money to be used for research where stem cells are derived from the destruction of the embryo.

2006

Pasteur Institute scientists provide evidence that muscle stem cells might retain both template DNA strands during cell division, resulting in conservative rather than semiconservative DNA replication.

Semiconservative replication would produce two copies that each contained one of the original strands and one entirely new strand.
The deciphering of the structure of DNA by Watson and Crick in 1953 suggested that each strand of the double helix would serve as a template for synthesis of a new strand. However, there was no way of guessing how the newly synthesized strands might combine with the template strands to form two double helical DNA molecules. The semiconservative model seemed most reasonable since it would allow each daughter strand to remain associated with its template strand. That the semiconservative model was correct was verified by the Meselson-Stahl experiment and other even more revealing experiments that allowed for autoradiographic visualization of the distribution of old and new strands within replicated chromosomes.

2004-2005

Hwang Woo-Suk claims to have created several human embryonic stem cell lines from unfertilised human oocytes. The lines are later shown to be fabricated
Hwang Woo-Suk () (born 29 January, 1953) is a South Korean biomedical scientist.

He was a professor of theriogenology biotechnology Seoul National University (dismissed on March 20, 2006) who rose to fame after claiming a series of remarkable breakthroughs in the field of stem cell research. Until November 2005, he was considered one of the pioneering experts in the field of stem cell research, best known for two articles published in Science magazine in 2004 and 2005 where he fraudulently reported to have succeeded in creating human embryonic stem cells by cloning. Both papers have been editorially retracted after being found to contain a large amount of fabricated data. He has admitted to various lies and frauds.

On May 12, 2006, Hwang was "indicted on embezzlement and bioethics law violations linked to faked stem cell research."

2003

Dr. Songtao Shi of NIH discovers new source of adult stem cells in children's primary teeth

Researchers at the Whitehead Institute announced in 2003 that they had successfully used embryonic stem cells to produce haploid, male gametes. They found embryonic stem cells that had begun to differentiate into embryonic germ cells and then further differentiated into the male haploid cells. When injected into oocytes, these haploid cells restored the somatic diploid complement of chromosomes and formed blastocysts in vitro. The online edition of Nature Medicine published a study on January 23 which stated that the human embryonic stem cells available for federally funded research are contaminated with non-human molecules from the culture medium used to grow the cells.