Stem cells from a human embryo have been safely implanted into 12 people’s brains in an experiment that could lead to advances in treating Parkinson’s. The goal is to coax the cells into boosting Parkinson’s patients’ dopamine supply. The small-scale study at the University of California’s Irvine campus shows some evidence of increased dopamine cell numbers, but they’re hard to count and one specialist not involved in the study tells the MIT Technology Review he finds the results “a bit disappointing”. That the patients’ condition isn’t getting worse is progress, though. The first time implanted cells were used to try to ameliorate Parkinson’s symptoms, in the 1980s, the cells were from aborted foetuses, not embryos, and some patients suffered “nightmarish” side effects. The study is being sponsored by a subsidiary of Bayer, which is subject to strict German limits on stem cell use but has found a way found them by doing the work in the US using cells derived from stocks created in Wisconsin before a 2007 legal cut-off date.