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Stem cells pre-treated with cancer drug might lead to safe, effective therapy for Parkinson's

Brazilian researchers at D'OR Institute for Research and Education (IDOR) and Federal University of Rio de Janeiro (UFRJ) have taken what they describe as an important step toward using stem cell-generated neurons as a treatment for Parkinson's disease. Using an FDA approved substance for treating stomach cancer, the researchers were able to grow dopamine-producing neurons derived from embryonic stem cells that remained healthy and functional for as long as 15 months after implantation into mice, restoring motor function without forming tumors.

Parkinson's, which affects as many 10 million people in the world, is caused by a depletion of dopamine-producing neurons in the brain. Current treatments include medications and electrical implants in the brain, but these can cause severe adverse effects over time and they also fail to prevent the disease’s progression. While several studies have indicated that transplanting embryonic stem cells improves motor functions in animal models, they also indicated there is a risk of tumors developing from the cells.

To address this issue, the researchers tested what happens when undifferentiated mouse embryonic stem cells are pre-treated with mitomycin C, a drug already prescribed to treat cancer. The substance blocks DNA replication and prevents the cells from multiplying out of control.

The researchers were led by Stevens Rehen, Ph.D., UFRJ professor and IDOR researcher. They tested their theory using mice with Parkinson's. The animals were separated into three groups: The first, a control group, did not receive any stem cells; the second received stem cells not treated with mitomycin C; and the third group received mitomycin C-treated cells.

After an injection of 50,000 untreated stem cells, the animals of the second group showed improvement in motor function but all died between three and seven weeks later. These animals also developed intra-cerebral tumors.

In contrast, animals receiving the treated stem cells showed improvement in the Parkinson's symptoms and survived until the end of the observation period of 12 weeks post-transplant with no tumors detected. Four of these mice were monitored for as long as 15 months with no signs of pathology.

Furthermore, the scientists have also shown that treating the stem cells with mitomycin C induced a four-fold increase in the release of dopamine after in vitro differentiation.

"This simple strategy of shortly exposing pluripotent stem cells to an anti-cancer drug turned the transplant safer, by eliminating the risk of tumor formation," Dr. Rehen said. "Our technique with mitomycin C may speed the proposal of clinical trials with pluripotent cells to several human diseases."

The study appears this month in Frontiers in Cellular Neuroscience.


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