Nobel Prize in Physiology or Medicine 2012 — Progress in stem cell research Nobel Prize in Physiology or Medicine 2012 — Progress in stem cell research – SOMETHING ABOUT SCIENCE

Nobel Prize in Physiology or Medicine 2012 — Progress in stem cell research

Recently, the Nobel Prize in Physiology or Medicine was jointly awarded to Drs. John B. Gurdon and Shinya Yamanaka “for the discovery that mature cells can be reprogrammed to become pluripotent.” What does it mean to be pluripotent and why is it so important? Read on to find out.

Dr. John B. Gurdon (left) and Dr. Shinya Yamanaka (right)

In 1962, Dr. Gurdon discovered that cell specialization is reversible. Cells that make up different parts of our body are “specialized,” or have specific functions to perform. Think about nerve cells, heart cells, skin cells, liver cells: the list can go on and on. All of these cells arise from fertilization of an egg (i.e. sperm joining the egg) that leads to the formation of embryo. Embryo is a cluster of immature cells that eventually develop into a whole body. These cells are stem cells. They are unspecialized and have the potential to become, or differentiate into, any cell type. Dr. Gurdon’s finding was radical because, prior to that, this process of cell differentiation during development was though to proceed only in one direction: once immature cells differentiate into mature, specialized cells, they lose their ability as stem cells.

Dr. Gurdon’s experiment involved injecting nucleus (central part of a cell containing DNA) taken from intestinal cell of a frog into a frog egg that lacked nucleus. This modified egg still developed into a regular tadpole, proving that mature cells contain all the information (in DNA) needed to create a whole frog. The discovery was not appreciated greatly at the time, but over the years, it led to a new era of medical research, including the cloning of mammals – making a copy of an animal by taking the nucleus of its skin cell and putting it into the animal’s egg. Remember the first cloned animal in 1997, Dolly the sheep clone?

A diagram showing how Dolly the clone sheep was made. Image credit: Squidonius on Wikimedia Commons

Dr. Gurdon’s approach proved that we can make clones from nucleus of mature cells inserted into an egg, but the fundamental question still remained to be answered: Can an intact mature, specilized cell converted back into immature, unspecialized cell? (After all, having to use someone’s egg and asking someone to get impregnated with the modified egg is not that practical and creates ethical issues…) This is where Dr. Shinya Yamanaka’s work comes in.

In 2006, Dr. Yamanaka successfully reprogrammed mature skin cells from mice into immature, stem cells that could develop into any cell types of an adult mouse. He called these resultant cells, induced pluripotent stem (iPS) cells. This was a great step forward in stem cell research: now there is no more need to rely on eggs (embryos). Adult cells can be directly converted into stem cells, which can then develop into any desired cell type. This means that using a piece of skin, for example, we can generate nerves, heart, liver, or any other body parts!

A diagram showing how induced pluripotent stem (iPS) cells are generated and used to make other body parts.

What are the applications for induced pluripotent (iPS) cells? Both researchers and public can directly benefit from this new technology.

Researchers are using iPS cells to study disease mechanisms. Imagine if you had to remove a heart from a patient with genetic-heart disease to study the disease! Using iPS cell technology, researchers can use other cells (such as skin) to recreate diseased part of the body in question. The recreated part can also serve as a screening platform for therapeutic drug development. This “disease in the dish” approach is already being used to study genetic diseases, such as cardiovascular, nervous, and metabolic disorders.

For therapeutic use, iPS-cell-based research has the potential to cure diseases or injuries for which effective treatment is difficult or does not exist. For example, iPS cell research could replace diseased or lost cells in degenerative disorders, such as Parkinson’s disease and type-1 diabetes. It could also be used for the treatment of spinal cord injury or heart injury, as well as regenerating lost hair!

Thank you for reading the post. See you next week! 🙂

References:
The Official Web Site of the Nobel Prize
Nobel Prize Press Release
Nobel Prize Advanced Information

Lynn Kimlicka

I am a scientist-turned writer and editor, who loves to read and write (more than doing experiments). I have a PhD in biochemistry and molecular biology, with a specialization in structural biology. My interests range widely, from life sciences to pop culture and arts to music. I am bilingual in English and Japanese.

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