When she entered medicine in the mid-1980s, Masayo Takahashi chose ophthalmology as her specialty, she said, because she wanted to have a family and thought the discipline would spare her from sudden work calls in the middle of the night, helping her best balance work and life.

Three decades later, the 55-year-old mother of two grown-up daughters is at the forefront of the nation’s — even the world’s — research into regenerative medicine.

In September 2014, she offered a ray of hope to scores of patients suffering from a severe eye condition when her team at the Riken institute’s Center for Developmental Biology in Kobe succeeded in a world-first transplanting of cells made from induced pluripotent stem (iPS) cells into a human body.

The operation, conducted as a clinical study, involved creating a retinal sheet from iPS cells, which were developed by Shinya Yamanaka, a researcher at Kyoto University. His 2006 discovery of iPS cells, which can grow into any kind of tissue in the body, won him a Nobel Prize in 2012.

During the 2014 procedure, the retinal sheet was transplanted into a female patient in her 70s with age-related macular degeneration (AMD), an eye disorder that blurs the central field of vision and can lead to blindness. The research team used iPS cells made from the patient’s own skin cells.

Takahashi made history again in March when she and her team carried out the world’s first transplant of retina cells created from donor iPS cells stocked at Kyoto University. The time and cost necessary for the procedure has been significantly reduced by using the cells, which are made from “super-donors,” people with special white blood cell types that aren’t rejected by the immune systems of receiving patients.

Takahashi was in Tokyo last week to speak at the Foreign Press Center and later with The Japan Times. She recounted the highlights of her 25-year research and the numerous legal and other challenges she has overcome.

Takahashi points to the day she led that first iPS transplant surgery — Sept. 12, 2014 — as the high point of her career so far. Because she worked so hard leading up to the surgery to confirm the safety of the retinal cells, she said that when the operation was over, she “was relieved and slept very well.”

It wasn’t the same for Yamanaka, who provided the stem cells to Takahashi, she said, chuckling. “Yamanaka-sensei couldn’t sleep well after the surgery because he didn’t know about the safety of the cells very well. I should have convinced him.”

Some researchers have expressed concern that iPS cell-derived cells have a higher risk of developing cancer. But Takahashi said she knew from the outset that the type her team was making, retinal pigment epithelium (RPE) cells, are extremely unlikely to cause tumors. RPE cells make up the pigmented layer of tissue that supports the light-sensitive cells of the retina.

“People in the world think iPS cells are very dangerous because we modify the genes,” she said. “The retinal pigment epithelium cell is very safe. We knew it from the beginning because we have never seen a metastatic tumor from this cell. Ophthalmologists know very well that this cell is very safe and very good.”

The Osaka native said she learned of — and became fascinated by — the possibility of using stem cells for eye diseases in the mid-1990s, when she took a year off from clinical practice at Kyoto University to work as a researcher at the Salk Institute in San Diego. She moved to Riken in 2006.

More than 2½ years have passed since that first iPS surgery, but the transplanted cells remain intact. According to Takahashi, it was not the goal of the research from the outset to improve the eyesight of the patient, who suffered from a very severe case of AMD. Before the surgery, the patient required injections of drugs into her eyeball every two months, but her visual acuity was declining. After the surgery, her acuity stabilized, and more importantly, she is happy, feeling that her vision has brightened and widened, Takahashi said.

Many challenges remain, however, to advance the technology and make it commercially available. One of the issues is cost, Takahashi said, adding that it will take until around 2019 before the cost of the iPS treatment for AMD will fall below ¥10 million. The first surgery in 2014 cost about ¥100 million in total, much of which was spent to maintain the clean room and culture the cells.

Still, Takahashi sees a huge potential for iPS cell therapy in her field and beyond.

“Every disease has potential to be treated by iPS cell-derived cells or ES (embryonic stem) cell-derived cells in the future,” she said, responding to a question on the chances of iPS cells being used to treat ALS, a rare, degenerative neurological disease for which there is currently no cure.

She said she has learned through her experience that some patients are very happy with small improvements.

“For ALS, at first, I thought, it’s a systemic, whole-body disease, so I didn’t know how they can fix it,” she said. “But a doctor (who specializes in ALS) said, ‘it’s OK, if one finger moves, it’s (still) OK.’ So I realized that some benefit will come from cell therapy.”

A Matter of Health is a weekly series on the latest health research, technology or policy issues in Japan. It appears on Thursdays.

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