By Alice Park
September 12, 2014

Researchers at the RIKEN Center for Developmental Biology in Japan surgically transplanted a sheet of retinal pigment cells into the eye of a 70-year old woman on Friday.

The cells are the first induced pluripotent stem cells, or iPS cells, given to a human patient. They were made by Masayo Takahashi, who grew them from the patient’s own skin cells, which were treated with four genetic factors to revert back to an embryonic-like state. Takahashi then soaked the cells with the appropriate growth factors and other compounds so they developed into retinal pigment cells.

The patient was losing her sight due to macular degeneration, because her retinal pigment endothelial cells were damaged by an overgrowth of blood vessels. Replacing them with a new population of cells can restore her sight.

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Stem cell scientists are starting to test their treatments in eye-related diseases, because parts of the eye are protected from the body’s immune system, which could recognize the introduced cells as foreign and destroy them. That’s not a problem with the iPS cells, since they are made from the patient’s own skin cells, but it’s an added safety net to ensure that the therapy is safe and hopefully effective.

Because iPS cells are genetically treated to erase their skin cell development and revert them back to an embryonic-like state when they can become any type of cell, there are still concerns about their safety when transplanted into patients. The U.S. Food and Drug Administration has not yet approved a trial involving iPS cells – so far, only stem cells made from excess IVF embryos have been approved for treating macular degeneration. A 19-member committee of the Japanese ministry of health approved the experimental procedure four days ago, according to Nature, after Takahashi made her case, with the help of Dr. Shinya Yamanaka of Kyoto University, who shared the 2012 Nobel Prize for discovering iPS cells.

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Japan’s stem cell scientists are hoping the surgery is a success; the field has been struggling since a well-publicized paper about a new way to make iPS cells was retracted amid allegations of fraud.

It’s not known whether the cells will continue to grow and form abnormal tumors, or whether they will migrate to other parts of the body. But now that the first patient has received them, those questions – and more, about the effectiveness of stem cell therapy – might be answered soon.

Contact us at editors@time.com.

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