Stem cell research shows promise for treating Parkinson's disease. Studies have found that transplanting embryonic stem cells or neural stem cells into animal models of Parkinson's can reduce symptoms by generating new dopamine-producing cells. However, many of these transplanted cells have failed to maintain their function over time or have caused tumor formation. A clinical trial in Peru found that transplanting bone marrow-derived stem cells into the brains of Parkinson's patients improved their symptoms, but long-term data is still needed. Future research aims to develop safer and more effective stem cell therapies by improving protocols and understanding how to support long-term cell survival and specialization without tumor risks.