Page 24 - Revista científica IESBrugulat 2016/17

WALLACE RAVVEN

INTERVIEWS SHINYA

YAMANAKA

(MOST INTERESTING PARTS)

There has been great enthusiasm and confidence for nearly 20 years that the use of stem cells will lead to powerful new
treatments for a range of diseases. Now, 10 years after your discovery, what treatments have been developed?

We are still in the early stages. In 2014, Dr. Masayo Takahashi and her colleagues at the Riken Center for Developmental
Biology had great success using iPS cells to treat macular degeneration.
They took skin cells from a 70-year-old patient and derived iPS cells from them. They then differentiated the stem cells
(directed them “back down” the normal developmental path) to become adult retinal cells. These were transplanted into the
patient’s eye to treat the disease. That was a huge success. She sees much brighter now.

So these treatments are now on hold?

Yes. We are developing allogenic stem cell lines — stem cells from donors. They would not be the patient’s own, but
compatible cells to transplant into the patient, much like blood transfusions with compatible blood types.
We are performing rigorous quality tests, including sequencing the stem cells’ genomes to be sure the cells are free from
cancer-causing mutations. We perform tests on adult retinal cells generated from these stem cells to assure that they
function as normal retinal cells, and those cells are transplanted into mice or rats for a year to assure they are safe.

How many compatible donor cell lines do you expect will be needed to cover the Japanese population?

Not that many. One particular line — just one — can work for 17 percent of the Japanese population. We estimate that
altogether about 100 lines will suffice for the 100 million people in Japan.

How many lines would be needed for the more diverse United States population?

We would need only about 200 lines.

Was the promise of stem cells overstated?

In some ways, yes, it is overstated. For example, target diseases for cell therapy are limited. There are about 10: Parkinson’s,
retinal and corneal diseases, heart and liver failure, diabetes and only a few more — spinal cord injury, joint disorders and
some blood disorders. But maybe that’s all.