Stem Cell Research and Dolly the Sheep

       In 1981, scientists discovered a way to identify embryonic stem cells, in other words, the inner mass cell of a human embryo, in mice. Although the term "stem cell" has been recognized in the world of science and medicine since the late 19th century, the first time that stem cells were isolated from an organism did not happen until almost 100 years later. Despite these humble beginnings, the identification and use of stem cells ever since have transformed many aspects of medical and scientific research.
      In the late 1980s, the way diseases, such as diabetes and cancer, function and develop started to undergo a transformation. A group of scientists by the names of Mario Capecchi, Martin Evans, and Oliver Smithies joined to create the first "knockout mouse," which is a genetically modified mouse where a naturally occurring gene has been replaced by artificial DNA or is purposely removed. These mice were created using embryonic stem cells and a process by which similar strands of DNA switch genes, which is known as homologous recombination. Since this first took place in 1989, scientists have bred hundreds of mice that model human disease, therefore giving scientists a clearer understanding of diseases unlike ever before.
    Additionally, without stem cells, cancer research would never be the same. In 1997, Canadian scientists Dominique Bonnet and John Dick discovered that leukemia is derived from the same stem cells that make our blood cells, which was one of the first pieces of research affirming the idea that cancer comes from stem cells that have gone out of control.
      Another major contribution to medical research thanks to stem cells was the revelation of Dolly the Sheep, the first artificial animal clone made from adult stem cells, also in 1997. Unlike embryonic stem cells, adult stem cells can be found in matured tissue or organs, but they serve a similar function in treatments that require regeneration of cells, such as diabetes or heart attacks. Dolly's creation also made researchers realized that specialized cells could help recreate the animal that they came from or form a wide range of other cells, which is especially helpful to humans suffering from all kinds of medical conditions. Thanks to this sheep, research on adult stem cells rather than embryonic stem cells which raise ethical concerns, has expanded and set the basis for modern research using stem cells.
     Human and animal stem cell research has become much more complex and revolutionary ever since these discoveries at an incredibly fast pace. Today, stem cells are used to treat conditions including heart disease, diabetes, osteoarthritis, spinal cord injury, rheumatoid arthritis, strokes, and much more.

Sources:
https://stemcells.nih.gov/info/basics/4.htm
https://www.newscientist.com/article/dn24970-stem-cell-timeline-the-history-of-a-medical-sensation/
http://stemcell.childrenshospital.org/about-stem-cells/history/
https://dolly.roslin.ed.ac.uk/facts/the-life-of-dolly/index.html