Researchers at Kyoto University are set to begin clinical studies, possibly as early as next year, to verify a cell replacement therapy that uses human induced pluripotent stem (iPS) cells to treat Parkinson’s disease.
It would be the first time for nerve cells developed from iPS cells to be transplanted into the human brain.
The team at the university’s Center for iPS Cell Research and Application (CiRA), headed by stem cell pioneer Shinya Yamanaka, will apply for the project's approval in June from a review committee to be created within the university.
If the cell replacement therapy is proven to be effective, it could lead to the discovery of a cure for the degenerative disorder of the central nervous system. There currently are about 150,000 patients with Parkinson’s disease in Japan.
Parkinson’s disease damages dopamine-producing nerve cells, or neurons, in the brain. Although symptoms of the disease can be treated with conventional medicine, there is no cure for Parkinson’s.
Scientists are investigating how cell replacement therapy could be used to treat the disease. Clinical trials to transplant healthy nerve cells taken from deceased infants into patients’ brains have been performed overseas.
But the efficacy of such treatment has not been authenticated because of the difficulty of obtaining a sufficient amount of healthy nerve cells. Also, donated cells contain a variety of cells that are not dopamine-producing neurons.
According to a project developed by Jun Takahashi, a professor of neurosurgery at CiRA, the team will produce dopamine-producing nerve cells from iPS cells that are created from a patient’s own cells.
The synthetic neurons will then be injected into the central area of the patient’s brain at a precise location.
The main purpose of the project is to determine if such cell replacement treatment can be damaging to a patient’s health. But if the transplanted neurons function effectively, they could halt progress of the disease’s symptoms.
Because unwanted neurons can be produced in the process of formulating synthetic cells, the team has already developed a method to sort out useful neurons from a large amount of nerve cells. Animal tests have already proven the effectiveness of the neuron-screening method.
Transplanted iPS cells can also multiply prolifically in the human body and cause cancer and other tumors when they are transplanted before they develop into specific types of cells.
To confirm the safety of the transplantation of iPS-originated cells, a team of researchers at the Riken Center for Developmental Biology is currently conducting the world’s first clinical study to transplant retina cells produced from iPS cells into patients’ eyes.
Unlike retina cell transplantation, the transplantation of neurons in human brains will require image diagnostic methods, including magnetic resonance imaging (MRI), to observe the effectiveness of the treatment.
Kyoto University’s review committee will take six months or longer to discuss safety measures for the observation methods and other issues before approving the clinical trial for Parkinson’s disease treatment.
After it obtains the committee’s approval, the research team will begin preparation for producing iPS-originated nerve cells to be used in clinical tests. If the clinical trials deliver the expected results, the team plans to apply for further clinical trials based on the pharmaceutical and medical device law so that the treatment will be applicable to insurance.