7/15/2023 0 Comments Adult pluripotent stem cellsEach gene was inserted near the mouse Fbx15 gene, a gene that embryonic stem cells express during development in mice. They used retroviruses to insert each of the twenty-four genes into the chromosomes of differentiated mouse embryonic fibroblasts. In 2006, Takahashi and Yamanaka selected twenty-four candidate genes as factors that they hypothesized could possibly induce somatic cells to become pluripotent, and they began to test them one at a time. After these experiments with somatic cells, Takahashi and Yamanaka hypothesized that there were common factors, genes in particular, which caused somatic cells to become pluripotent stem cells. Other research groups such as Masako Tada's group in Japan in 2001 and Chad CowanÆs group in Massachusetts in 2005 combined embryonic stem cells with somatic cells to produce pluripotent cells. The Dolly experiment showed that scientists could reprogram the nucleus of somatic cells by transferring the contents of the nucleus into oocytes that have had their nuclei removed, a technique called somatic cell nuclear transfer (SCNT). Yamanaka also noted that experiments in cloning Dolly the sheep in 1996, conducted by Ian Wilmut, Angelica Schnieke, Jim McWhir, Alex Kind, and Keith Campbell at the Roslin Institute in Roslin, Scotland, influenced his work. Yamanaka claimed that Gurdon's work in reprogramming mature cells in frogs ( Xenopus) in 1962 influenced his own work in reprogramming differentiated cells. Yamanaka studied the work of John Gurdon, a researcher who had experimented with Xenopus frogs at the University of Oxford in Oxford, United Kingdom. Yamanaka worked to find new ways to acquire embryonic stem cells to avoid the social and ethical controversies surrounding the use of human embryos in stem cell research during the late twentieth and early twenty-first centuries. Yamanaka and others hypothesized that retroviruses could influence somatic cells to become stem cells. In 2004, Yamanaka began working at Kyoto University as a professor, where he studied factors that help an organism fend off retroviruses, which are single-stranded RNA viruses that can incorporate their genetic material into the DNA of a host cell. Yamanaka had earned an MD from Kobe University in Kobe, Japan in 1987. Takahashi was a post-doctoral researcher who had earned a graduate degree in biology at the Nara Institute of Science and Technology in Ikoma, Japan. Takahashi and Yamanaka worked together at Kyoto University. Takahashi and Yamanaka's 20 experiments showed that scientists can prompt adult body cells to dedifferentiate, or lose specialized characteristics, and behave similarly to embryonic stem cells (ESCs). Yamanaka received the Nobel Prize in Physiology or Medicine in 2012, along with John Gurdon, as their work showed scientists how to reprogram mature cells to become pluripotent. They called the pluripotent stem cells that they produced induced pluripotent stem cells (iPSCs) because they had induced the adult cells, called differentiated cells, to become pluripotent stem cells through genetic manipulation. Each worked at Kyoto University in Kyoto, Japan. Takahashi and Yamanaka also experimented with human cell cultures in 2007. In 2006, Kazutoshi Takahashi and Shinya Yamanaka reprogrammed mice fibroblast cells, which can produce only other fibroblast cells, to become pluripotent stem cells, which have the capacity to produce many different types of cells. Induced Pluripotent Stem Cell Experiments by Kazutoshi Takahashi and Shinya Yamanaka in 20
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