Scientists have transplanted human embryonic stem cells into primate laboratory animals modeled with Parkinson's disease and found "robust survival" of the cells after six weeks.
"Parkinson's disease was one of the first neurological disorders to be studied for potential replacement of lost neurons," Dr. D. Eugene Redmond of Yale University School of Medicine, said.
"Since the 1970s there has been significant progress with learning the required gene expression, growth factors and culture conditions for differentiating cells into apparent dopamine neurons," he said.
However, the researchers noted that transplanted dopamine neurons have not produced "long-lasting midbrain specific neurons when transplanted into rodents or monkeys" and there have only been pilot reports of functional improvement.
According to the study authors, their study tested the long-term survival and functional benefit of apparent dopamine neurons in monkeys modeled with Parkinson's disease.
As with other studies, their results found that the gene expression of the rate limiting synthetic enzyme for dopamine production, tyrosine hydroxylase (TH), was "transient" after transplantation, raising questions about the optimal cell stage and culture environment that favor graft survival and the factors that could impact cell transplantation. Once more, a more robust immunosuppression regimen than employed in other primate studies resulted in better cell survival.
"Our results demonstrate that pluripotent stem cell line-derived neurons retain the capacity to robustly survive and respond to cues in the primate brain," they wrote.
The study is published online for the journal Cell Transplantation.