Reprogrammed stem cells, or iPS cells, have never been used in a human clinical trial for Parkinson’s before. In this trial, adult stem cells are donated and “reprogrammed” into embryonic cells. Once they are manipulated they become pluripotent stem cells, which can be developed into cells capable of creating dopamine.
Parkinson’s disease is caused by a lack of dopamine producing cells in the brain. With decreased levels of dopamine, motor functions deteriorate and dementia can occur. However, it is believed that this can be reversed by creating dopamine-producing neurons through iPS cells.
Jun Takahasi of the Center for iPS Cell Research and Application (CiRA) at Kyoto University, told us, “There are decades of research using fetal tissue that are transplanted into the brain to replace the lost dopaminergic neurons. However, sources for fetal tissue are unstable. This clinical trial uses iPS cells from a hiPSC stock that can stably provide more iPS cells for future therapies. We produced dopaminergic neuron progenitors from these iPS cells. These progenitors when transplanted into the patient brain are expected to replenish the lost dopaminergic neurons.”
It was previously believed that iPS cells would cause malignant tumors. However, they were successfully used to restore normal brain function in monkeys during a two-year study, without any signs of tumors. Takashi said that the potential for tumors is always a concern when using pluripotent stem cells, but the protocol they have in place takes great care to assure the quality of cells, which reduces the risk.
“Demonstrating that iPS cell therapies are effective and safe for Parkinson’s disease will accelerate research for their use to build novel therapies for diseases of not just the brain but also other organs. In other words, success in this clinical therapy defends more resources being put into iPS cell research regardless of the disease,” said Takashi.
This clinical trial is in the process of recruiting seven Parkinson’s patients, yet Takahasi said it may be difficult to find patients to enroll, “Our criteria for patient eligibility is strict, so it may be difficult. At the same time, the media attention has led to numerous inquiries from Parkinson’s disease patients, so I am optimistic.”
Takahasi continued, “My goal is to find a cure for Parkinson’s disease. This treatment may not work for all patients (for example, the health of the patient may prohibit brain surgery), but success here would mean a large number of patients with no effective treatment options could suddenly see a great improvement in their quality of life.”