Japan's health ministry approved Monday the world's first clinical test in which artificially derived stem cells will be used to treat patients suffering from the loss of motor function due to spinal cord injuries.

With the approval, a team of researchers from Keio University, which filed a request for the test with the ministry, will start recruiting patients from fall to next winter.

(A health ministry panel approves on Feb. 18, 2019 the world's first clinical test in which artificially derived stem cells will be used to treat patients with spinal cord injuries.)

The team will inject neural stem cells produced from so-called induced pluripotent stem cells into four people who sustained injuries while playing sports or in traffic accidents.

"Finally, we are able to carry out a clinical study 20 years after the research began," Hideyuki Okano, a professor who is leading the project at Keio's School of Medicine, said in a press conference in Tokyo. "I'd like to offer a safe treatment to patients as early as possible."

Okano and his team have already succeeded in enabling a paralyzed monkey to walk again through the same approach.

It is the fifth time that the government has authorized clinical studies using iPS cells. The patients, aged 18 or older and to undergo the test treatment administered by the Keio team, will have suffered lost mobility and sensation in their limbs.

The cells will be injected within two to four weeks of the patients' accidents -- a period in which the treatment is believed to be effective.

Then for about one year, while the patients undergo rehabilitation, the team will observe the efficacy and safety of the cells, which will be created from iPS cells in storage at Kyoto University and kept frozen.

Kyoto University's Shinya Yamanaka won the Nobel Prize in physiology or medicine in 2012 for developing iPS cells, which can grow into any type of body tissue and are seen as a promising tool for regenerative medicine and drug development.

The main purpose of Keio's study is to confirm the safety of the neural stem cells. The team will initially limit the number of cells they will transplant to 2 million per patient but plan to increase that to up to 10 million in the future.

(Keio University professor Hideyuki Okano speaks in Tokyo on Feb. 18, 2019, about the use of induced pluripotent stem cells to treat patients suffering from the loss of motor function due to spinal cord injuries.)

Every year, some 5,000 people sustain spinal cord damage in Japan, and the number of people living with some sort of spinal cord-related injury is estimated to total over 100,000.

People with existing spinal cord injuries are mostly in the chronic phase and, therefore, will not be subject to the upcoming clinical trial.

But Masaya Nakamura, a Keio professor of orthopedics, who is in charge of the procedures, said the team wants to confirm "within two to three years" the safety of the treatment for patients with chronic spinal cord injuries.

On Monday, a panel at the ministry also reviewed another plan for a clinical test in which corneas produced from iPS cells will be transplanted to treat eye diseases. The trial was proposed by an Osaka University research team.

The panel did not yet come to a decision on the cornea trial and left the outcome to future discussions.

Among other clinical tests with iPS cells, the government-backed Riken institute conducted the world's first transplant of retina cells grown from iPS cells to an individual with an eye disease in 2014.

Kyoto University also began a clinical test using iPS cells to treat Parkinson's disease last year.