Stem cells are undifferentiated cells with the ability to divide indefinitely and develop into specialized cells throughout the body. These cells have long been a research and therapeutic focus, with laboratories worldwide working to realize the cells’ potential in treating injury and disease.

The field of stem cell research is rapidly progressing. But how well do you know these cells? Read on for five facts about stem cells and their journey toward the clinic.

1. Human embryonic stem cells were first isolated and grown in the lab in 1998, by James Thompson of the University of Wisconsin in Madison and John Gearhart of Johns Hopkins University. This was one year after Dolly the sheep was created by Ian Wilmut and his team at Edinburgh’s Roslin Institute. Dolly was the first artificial animal clone ever created.
2. There are four classes of stem cells: totipotent, multipotent, pluripotent and unipotent.
   • Totipotent cells can develop into cells that eventually make up every cell in the embryo and fetus, including placental cells. These cells are only present within a few cell divisions of fertilization.
   • Multipotent stem cells can differentiate into multiple cell types within a particular tissue, organ or system.
   • Pluripotent stem cells can become any type of cell in the body and are what is generally termed embryonic stem cells.
   • Unipotent cells can self-renew and become a single mature cell type.
3. The first human embryonic stem cell-derived medical treatment was administered to a person with a spinal injury in 2010 by the stem cell company Geron. Only five of the intended ten patients received the treatment, as Geron halted the trial to focus on cancer therapies. The patients were later tracked by the company Asterias, which bought Geron’s stem cell therapy. Additional trials for spinal injury using embryonic stem cells are now in process, as well as promising trials for two eye diseases by Advanced Cell Technology.
4. Induced pluripotent stem cells are the term used for adult stem cells that have been genetically engineered to act like embryonic stem cells. These cells, iPSCs for short, do not require destruction of an embryo so are incredibly valuable research tools. iPSCs were first produced by Dr. Shinya Yamanaka of Kyoto University in 2006 by inserting four genes into adult stem cells. In 2013, Yamanaka won the Nobel Prize for his research, which he shares with Sir John Gurdon, PhD of the University of Cambridge. Sir Gurdon replaced the immature nucleus of a frog egg cell with the nucleus from a mature intestinal cell. The altered egg cell developed into a normal tadpole.
5. Fraudulent claims caused controversy in embryonic stem cell research in 2005 when Dr. Woo Suk Hwang of Seoul National University in South Korea published a paper claiming that his team had generated human embryonic stem cells via the same methodology used to create Dolly. Soon, the claims were proven false and the paper retracted. Years later, in 2013, Dr. Shoukhrat Mitalipov of the Oregon National Primate Research Center generated human embryonic stem cells using therapeutic cloning from fetal cells and was therefore able to do what Dr. Hwang had retracted years earlier. Therapeutic cloning using adult cells was demonstrated by two research teams in 2014. Dr. Dieter Egli and his group at the New York Stem Cell Foundation and Dr. Young Gie Ghung from CHA University in Seoul independently reported their work.

Want to learn more? Check out some unique reagents helping to advance stem cell research, or read one of our recent related blog posts:

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