Stem Cell Infusions Show Mixed but Promising Results in Parkinson’s Trial

A new clinical trial has tested whether stem cell infusions could help improve movement in people with Parkinson’s disease. The results suggest that three rounds of treatment may lead to meaningful benefits, although a strong placebo effect makes the findings more complicated to interpret. The phase 2 study involved 45 people with mild to moderate Parkinson’s, treated between late 2020 and mid-2023. Participants were randomly split into three groups: one group received three infusions of donor-derived mesenchymal stem cells (allo-hMSCs); another group had one placebo infusion followed by two stem cell infusions; and the third group had three placebo infusions. Each treatment was given 18 weeks apart, and everyone was followed for 88 weeks in total. The main goal was to see how many people showed at least a 5-point improvement on a widely used Parkinson’s movement scale (the MDS-UPDRS Part III) when assessed off medication. By week 62, the group that had three stem cell infusions showed a clear advantage over placebo, with more people improving by at least 5 points. Using a tougher cut-off of 11 points, the results still favoured the three-infusion group. Interestingly, the group that only received two infusions did worse than placebo, both at week 62 and later at week 88. This suggests that consistency and full dosing may be important for the therapy to have an effect. One striking finding was how well the placebo group did. Instead of showing the expected gradual worsening of motor symptoms over nearly two years, all groups improved. Researchers believe this reflects a strong placebo response — something that is well-known in Parkinson’s trials. However, by week 88, the differences between the three-infusion group and placebo became clearer, hinting that the placebo effect may have faded while the benefits of stem cells persisted. Looking at more substantial improvements, nearly half the people in the three-infusion group achieved at least a 12-point improvement by week 88, compared to fewer in the placebo group. This further supports the idea that three doses of stem cells may have a real impact. As for safety, the treatment was generally well tolerated. Only mild and temporary side effects were reported, such as fatigue, flu-like symptoms, headache, or short-lived high blood pressure. A few people showed immune system markers suggesting a reaction to donor cells, but these were later confirmed to be unrelated to the treatment. No severe side effects occurred. Overall, the trial suggests that repeated infusions of donor stem cells could improve motor symptoms in Parkinson’s and do so safely. However, the strong placebo response means more research is needed to confirm the true benefit. Larger trials with stricter controls will be required before this approach can be considered a reliable treatment option.