Promising new results from a rat study suggest that an effective stem cell therapy for patients with Parkinson’s disease could be within our grasp. After injecting brain cells derived from human stem cells into rats with models of the condition, the rodents’ ability to control movement was restored. Furthermore, after examining their brains, they found that the cells brought dopamine levels back to normal. While more work needs to be done, the study brings scientists one step closer to the use of stem cell transplants in human trials. The work has been published in Cell Stem Cell.
Parkinson’s disease is a degenerative condition in which dopamine-producing cells in part of the brain are progressively damaged and lost over time. This causes a gradual decline in dexterity and the ability to control the speed of movement. While there is no cure, therapies such as drugs and brain stimulation can reduce symptoms, but their effectiveness wanes over time.
A different treatment approach, which involved transplanting brain tissue from fetal cells, was trialed fairly recently, but it had mixed results. Some patients had long-lasting benefits, but some experienced involuntary movements which were driven by the graft. The use of fetal cells also has ethical considerations, and supplies are scarce.
But there could be a different way to replace the damaged tissue in patients’ brains: stem cells. Before they can be used in humans, however, researchers need to make sure that they survive and functionally integrate into the brains of animals. To find this out, researchers from Lund University took dopamine neurons (brain cells) derived from human embryonic stem cells and injected them into rats with a model of Parkinson’s disease.
Not only did the cells exhibit long-term survival in the rodents’ brains, they also brought dopamine levels back to normal in just five months. Furthermore, the cells established long distance connections with other brain regions, and communicated with the correct target areas. These crucial outcomes allowed motor function (the control of movement) to be restored in the animals with a similar potency to that observed when human fetal neurons are transplanted. This suggests that stem cells could be a viable alternative to using fetal cells, which is important given the practical and ethical issues surrounding these cells.
“It’s a huge breakthrough in the field [and] a stepping stone towards clinical trials,” said lead researcher Malin Parmar. Although it’s still early days, the researchers believe that these trials could begin as early as 2017.