April 17, 2017 1:30 pm JST

iPS cell stockpiling system brings treatment closer to patients

Time, costs can be trimmed, but risk of rejection remains

ATSUNOBU TAKESHITA, Nikkei staff writer

Researchers perform the world's first transplant using donor-derived iPS cells at Kobe City Medical Center General Hospital.

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 late last month. Compared to using the patient's own cells to create the iPS cells, the cost and time required to prepare for a surgery can be reduced to less than one tenth, which could make iPS cell treatments more accessible to patients.

The clinical study on March 28 was conducted by the team involving the government-affiliated Riken research institute, Kobe City Medical Center General Hospital, Kyoto University and other entities.

The patient was a man in his 60s living in Hyogo Prefecture 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.

Cold storage

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. Although cells will die if they are kept as they are after being removed from body, the freezing method allows for long-term storage. After thawing, the cells can be reactivated as living cells.

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(CiRA).

The iPS cells were created from the blood of donors with rare HLA types that are less susceptible to rejection. This minimizes the risk of the transplanted cells being rejected by patients' immune system as they come from other individuals. Researchers obtained blood samples from donors with the HLA types.

The distribution of the iPS cells began in August 2015 to universities and other entities. CiRA plans to distribute the iPS cells, which can cover 30-50% of the Japanese population by the end of fiscal 2017 and 80 or so percent by the end of fiscal 2022.

The major benefit of the stock project is that treatment cost and time for preparation can be dramatically reduced.

If a patient's own cells are used, it takes more time and money to check whether the cells will turn cancerous.

The first transplant of retina cells made from iPS cells of the same patient, conducted in 2014, cost about 100 million yen ($924,000) and took about 10 months to prepare.

The latest transplant is expected to cost only several million yen. The length of time from obtaining a patient's consent to performing the surgery was cut to one and a half months.

Treatment using cells of other individuals can significantly cut costs as large quantities of iPS cells can be produced from a single donor.

The time needed to prepare for the surgery can also be made much shorter as there is no need to create iPS cells from each patient.

Soaring medical costs have become a huge issue in Japan, so the reduction in the costs would promote the iPS-based regenerative medicine.

Problems remain

The cell stock, however, is not immune from problems.

The rejection risk cannot be wiped out completely as long as the cells are not a patient's own.

Although the latest transplant did not use immunosuppressant medication in the patient. Yasuo Kurimoto, the head of the hospital's ophthalmology department, 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 would be unnecessary, and the fear of further losing vision would be reduced.

Riken plans to conduct a similar clinical study for at least five patients with age-related macular degeneration within the next two years.

If symptoms believed to stem from rejection are observed in patients, 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.

The clinical study is also planned for patients with Parkinson's disease and degenerative disorders of the central nervous system, as well as spinal cord injury.

Expectations are especially high that the iPS therapy can treat such intractable conditions.

Takahashi likened the path to the practical application of the treatment to mountaineering, saying, "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.

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