The medicine will be the first tissue-engineered medical product created from stem cells.
An expert panel at the Ministry of Health, Labor and Welfare approved the proposed therapy on Nov. 21.
The health minister is expected to officially approve the treatment by the end of next month. Treatment for patients will likely be covered by the national health insurance program.
The ministry assessed the new therapy under the system that prioritizes new drugs with a potential to have a dramatic effect for speedy approval.
The medical product, called Stemirac, was jointly developed by Osamu Honmo, professor of cerebral nerve at Sapporo Medical University, and Nipro Corp., a leading medical equipment maker based in Osaka.
Under the therapy, researchers extract mesenchymal stem cells that have the ability to transform into bone or blood vessels from bone marrow fluids of patients whose spinal cord has been damaged.
After they cultivate 50 million to 200 million mesenchymal stem cells to create Stemirac, they inject it into patients intravenously within a couple of months after their injury.
Researchers say mesenchymal stem cells will concentrate in damaged parts of bone marrow on their own, reduce inflammation, work to promote regeneration of nerves or turn into nerve cells.
Honmo and his colleagues have conducted a clinical trial led by doctors to verify the safety and effectiveness of the proposed treatment since 2013.
Of 13 patients who received the injection between three weeks and eight weeks after injury and underwent rehabilitation, 12 showed improvement at least by one rank defined by the American Spinal Injury Association Impairment Scale, which describes the extent of the spinal cord injury.
One of the patients showed dramatic improvement by regaining the ability to move the feet after originally falling into the category where patients had no motor or sensory functions, according to the researchers.
Exactly how mesenchymal stem cells work remains a mystery. The expert panel’s approval is conditional.
All patients using cell and tissue drugs derived from mesenchymal stem cells will be monitored for about seven years for safety and efficacy.
Akifumi Matsuyama, professor of regenerative medicine at Fujita Health University, urged caution in assessing the results of the clinical trial.
“The nervous system may have recovered somewhat because the injection of the drug was made not long after the patients were injured,” he said.
An estimated 5,000 people suffer spinal cord injuries annually in Japan, totaling more than 100,000 patients in total.
A research team at Keio University plans to conduct a clinical trial with the use of human iPS cell-derived neural cells to treat spinal cord injuries.
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