James Alexander Thomson

James Alexander Thomson is an American developmental biologist who is best known for deriving the first human embryonic stem cell line. He serves as director of regenerative biology at the Morgridge Institute for Research in Madison, Wisconsin, and is a professor at the University of Wisconsin School of Medicine and Public Health. In 2007, he became an adjunct professor in the Molecular, Cellular, and Developmental Biology (MCDB) Department at the University of California, Santa Barbara. He is a member of the National Academy of Sciences. In 2008, TIME magazine, named him one of 100 of the most influential people in the world

Since joining the Wisconsin National Primate Research Center, Thomson has conducted pioneering work in the isolation and culture of non-human primate and human embryonic stem cells, undifferentiated cells that have the ability to become any of the cells that make up the tissues of the body. Thomson directed the group that reported the first isolation of embryonic stem cell lines from a non-human primate in 1995, work that led his group to the first successful isolation of human embryonic stem cell lines in 1998. On November 6, 1998, Science published the results of this research in an article titled Embryonic Stem Cell Lines Derived from Human Blastocysts.

On November 22, 2007, the New York Times reported that Thomson's laboratory had devised a method for modifying human skin cells in such a way that they appear to be embryonic stem cells without using a human embryo. This work was published in the journal Science in late 2007.