Over 95% of mouse genes are similar to ones found in humans. Image © Understanding Animal Research.
The 2007 Nobel Prize in Physiology or Medicine was awarded to three researchers whose work led to the creation of genetically modified mice. This in turn made it possible to learn what genes do by studying what happens when they are missing. During the 1980s, Mario Capecchi and Oliver Smithies each found ways to “knock out” genes and replace them with new genetic material. Meanwhile, Martin Evans developed a technique to remove stem cells from mouse embryos and grow them in the lab. These cells are important because they can become any kind of cell. Evans and his colleagues then figured out how to put embryonic stem cells into a mouse embryo to produce hybrid animals whose tissues contain two sets of genetic material. Some hybrids had stem cell DNA in their sperm or eggs so when two of these animals mated, their offspring carried stem cell DNA in every cell. When Evans collaborated with Capecchi and Smithies, the result was the “knockout mouse.”