News Neuroscience Early Parkinson’s trials revive stem cells as a possible treatment In two small clinical trials, stem cell therapies caused no apparent trouble in the brain Injections of cells (shown here frozen in vials) may help restore missing nerve cells in the brains of people with Parkinson's disease. Mark Tomishima By Laura Sanders 2 hours ago Two small clinical trials revive hope for an old idea: Cells injected into the brain might replace the nerve cells that die in Parkinson’s disease. The studies, published April 16 in Nature, represent early steps for stem cell therapies that aim to replace these dead cells in the brain — and stop Parkinson’s and the movement problems, tremors and rigidity that it brings. In both trials, scientists injected cells derived from stem cells that would go on to become specialized neurons that pump out the chemical messenger dopamine. These are the crucial cells in the brain that die in Parkinson’s disease, a relentless neurological disease that is estimated to affect over 8 million people worldwide. Sign up for our newsletter We summarize the week's scientific breakthroughs every Thursday.