TOKYO Japanese researchers performed the world's first transplant of retina cells made from donor-derived induced pluripotent stem (iPS) cells into a patient's eye in late March. Compared with using the patient's own cells to create the iPS cells, the cost and time needed to prepare for surgery can be reduced to less than one tenth.
The clinical study on March 28 was conducted by a team involving the government-affiliated research institute Riken, Kobe City Medical Center General Hospital, Kyoto University and other entities.
The patient was a man in his 60s who suffered from age-related macular degeneration, a condition that can lead to loss of vision. The team injected a solution containing about 250,000 retina cells grown from iPS cells into the back of the patient's right eye.
The iPS cells used in the procedure had been stored in a stockpile, called the iPS cell stock, after being reprogrammed from the donated blood cells.
The iPS cell stock project works by adding a liquid medium into living cells and storing them in liquid nitrogen freezers at a temperature of minus 196 C. Cells will die if they are kept as they are after being removed from body, but freezing allows for long-term storage.
The development of the iPS cell stock system was led by Nobel Prize laureate Shinya Yamanaka, the head of Kyoto University's Center for iPS Cell Research and Application, or CiRA.
The iPS cells were created from the blood of donors with rare HLA types -- the body's natural marker that identifies its own cells -- that are less susceptible to rejection. This minimizes the risk of cells transplanted from other individuals being rejected by a patient's immune system.
Distribution of iPS cells to universities began in August 2015. CiRA plans to distribute the cells, which will cover 30-50% of the Japanese population by the end of the fiscal year starting April 2017 and around 80% by the end of fiscal 2022.
If a patient's own cells are used, it takes more time and money to check whether the cells will turn cancerous or develop some other defect.
Treatment using cells of other individuals means that large quantities of iPS cells can be produced from a single donor.
The first transplant of retina cells made from iPS cells of the same patient, conducted in 2014, cost about 100 million yen ($917,000) and took about 10 months to prepare.
The latest transplant is expected to cost only a few million yen, while the length of time from obtaining the patient's consent to performing the surgery was cut to one and a half months.
The cell stock, however, is not immune from problems.
The risk of rejection cannot be eliminated completely as long as the cells are not a patient's own.
The latest transplant did not use immunosuppressant medication in the patient, but Yasuo Kurimoto, the head of the hospital's ophthalmology department and the man who conducted the surgery, said, "We will carefully study the results for at least a year."
The core aim of the clinical study was to confirm the safety of the procedure.
Although the patient's eyesight will not improve substantially, the regular administration of drugs will be unnecessary, and the possibility of further deterioration of vision is reduced.
Riken plans to conduct similar clinical studies for at least five patients with age-related macular degeneration within the next two years.
If symptoms believed to stem from rejection are observed, the institute may have to overhaul plans for the clinical study.
"It will take two to three years to draw the final conclusion about the results," said Masayo Takahashi, the Riken project leader.
Clinical studies are also planned for patients with Parkinson's disease and spinal cord injuries.
Expectations are especially high that iPS therapy can treat such intractable conditions.
Takahashi likened the path to the practical application of the treatment to mountaineering, "We are now at the fifth station of this mountain."
This marks considerable progress from the "second or third station" described in 2014 when the first transplant was performed.