A Japanese group said Thursday that it succeeded in improving symptoms of Parkinson's disease patients with nerve cells produced from induced pluripotent stem (iPS) cells.

Symptoms improved in four of the patients participating in a clinical trial in which nerve cells made from iPS cells were transplanted into their brains, said Kyoto University Hospital and the national university's Center for iPS Cell Research and Application (CiRA).

Sumitomo Pharma, which supplied the nerve cells, plans to apply for a state approval for the treatment under a fast-track system for regenerative medicine products that gives approvals on certain conditions for use over limited periods.