RIKEN (the Institute of Physical and Chemical Research) in late February asked the health and welfare ministry for permission to carry out a clinical study that will use induced pluripotent (iPS) cells to treat an eye disease.

If everything goes smoothly, the treatment will be carried out early next year. In examining the request, the ministry must take utmost care to ensure safety in the clinical study — the most important thing for the clinical study.

The clinical study, believed to be the world’s first using iPS cells, will make a step forward in realizing the dream of Dr. Shinya Yamanaka at Kyoto University, the creator of iPS cells, that the cells would someday be used for clinical purposes.

Dr. Yamanaka received the Nobel Prize in Physiology or Medicine 2012 for creating iPS cells, which can develop into all types of cells in the body, by introducing only four genes into mature cells taken from the skin of a human.

The clinical study will aim at curing age-related macular degeneration, an eye disease affecting an estimated 700,000 people in Japan. Abnormal, easy-to-break blood vessels multiply in the retina, and bleeding from them damages the macula or the yellow spot in the center of a visual field. As a result, things seen in the center of a visual field will appear deformed or blackened. In the worst case, a person with the disease suffers a loss of eyesight.

Six patients will be chosen for the clinical study at the Kobe hospital of the Foundation for Biomedical Research and Innovation.

First, iPS cells will be made from the skin of each patient and be grown into a type of retina cell. The retina cells, in the form of a sheet, will be transplanted after the abnormal blood vessels and damaged cells are removed.

At least four years will be spent doing follow-up observations. Since the conditions of the six patients are serious, significant recovery of their eyesight is not expected.

The main purpose of the clinical study is to ensure that the transplant of iPS cells into a human body is safe and to lay the groundwork for the next step of iPS cell-based medical treatment.

Before permitting the clinical study, the ministry should confirm that rejection will not occur and that the risks involved in changing the retina cells are within acceptable limits.

It also should determine how many times tests on animals must be carried out in advance to make the treatment as effective as possible as well as to reduce to an acceptable level the probability of the iPS cells becoming cancerous.

The ministry also should make sure that the patients do not misunderstand the clinical study and are ready to receive treatment even if their eyesight is not likely to improve dramatically.

It is hoped that the clinical study will be successful and help lay a foundation for the progress of advanced medicine in Japan.