Long-term safety of iPS spinal cord therapy confirmed in Japan

Long-term safety has been confirmed after neural progenitor cells derived from induced pluripotent stem cells, or iPS cells, were transplanted into patients with spinal cord injuries, a team of researchers at Keio University said Tuesday.

The team, which conducted the world’s first clinical study of the treatment, plans to launch an investigator-initiated clinical trial as early as next year to bring it into practical use.

Between 2020 and 2025, the team, including Professor Hideyuki Okano, transplanted about 2 million iPS cell-derived neural progenitor cells into each of four patients in the subacute stage of spinal cord injury within four weeks of their injuries.

Last year, the team reported the results of the one-year postoperative follow-ups of the patients, finding no major safety concerns as well as improvements in physical function in some of them.

The latest report said that no major safety issues, including tumor formation, were observed in any of the four individuals even two to four years after the surgery, and that no clear deterioration in physical function was confirmed.

The team also found, through a reanalysis of the one-year postoperative data, that two patients regained some muscle control despite having completely lost motor function before treatment.

However, the team said that the effectiveness of the treatment needs to be verified in subsequent clinical trials, given the small sample size.

The findings were published in the online edition of the international medical journal Nature Medicine.