Japan has given a stem cell therapy the "green light" for the treatment of spinal cord injuries in humans.
The country has unique regulations for the approval of regenerative medicines — therapies can be sold even if they show only hints of efficacy, on the condition that follow-up data is collected.
Therefore, four candidates will be selected for a trial, following the approval by Japan’s Health Ministry on Monday. The participants must have sustained a spinal cord injury 2-4 weeks prior, and must have lost mobility and sensory functions as a result.
The work is being lead by a research group from Keio University.
Significant progress has been made in the regenerative medicine/CNS space in the last 12 months:
- A biodegradable nanoscaffold was developed for the transplantation of stem cells into the spinal cord and was shown to be a viable approach in animal models
- Bioengineered spinal discs implanted into goats showed promise
- Human induced pluripotent stem cell-derived neurons grafted into rodents suppressed epileptic seizures
While these milestones are significant for the field, they are a far stretch from demonstrating efficacy of such a treatment, and independent researchers warn that the approval is premature.
What is the mode of action?
The work paving the way for the proposed trial has not yet been published.
However, Nature report that the results describe a trial of 13 people who received intravenous infusions of stem cells extracted from their own bone marrow. 12 of the 13 regained some lost sensation and movement.
The Japan Times reported that the approach has enabled a paralyzed monkey to walk again, and noted that Kyoto University’s Shinya Yamakana won the Nobel Prize in physiology/medicine for his work in regenerative medicine, where he developed induced pluripotent stem cells. Kyoto University is also involved in the trial.
Journalists from Nature approached 10 specialists with expertise in stem cell science or spinal cord injuries who raised their concern about the unpublished results that provided the basis for the approval
- The trial was not double-blinded, which is the gold standard for assessing treatment efficacy
- It was too small
- The therapy is administered intravenously
“The fact that the cells are trapped in the lungs makes it difficult to see how they can be effective in the spinal cord,” -Pamela Robey, a stemcell researcher at the US National Institutes of Health in Bethesda, Maryland.
Research team leader, Professor Hideyuki Okano, has published work in PLOS ONE describing the efficacy of a stem cell treatment tested in a non-human primate model, whereby the cells were transplanted into the cervical spinal cord. Okano is less despondent:
“It’s been 20 years since I started researching cell treatment. Finally we can start a clinical trial,” Okano said at a news conference in Tokyo. “We want to do our best to establish safety and provide the treatment to patients.”