Limitations of Stem Cell Therapy for Parkinson's Disease.

Stem cell therapy, as a potential treatment for Parkinson's disease (PD), has been investigated in many clinical trials for its effectiveness. However, the therapeutic outcomes have shown considerable variability. This may be due to certain limitations of stem cell therapies, such as the inability to ameliorate non-motor symptoms or modify underlying disease mechanisms, and the limited applicability in certain patient populations. Combinations with the recently emerging gene therapy and other available technologies are expected to make up for or break down these limitations of stem cell therapy, thereby broadening its scope of application. In this review, we will discuss the limitations of stem cell therapy in terms of pathogenesis, symptoms, and population, as well as possible coping strategies to enhance the effectiveness of stem cell therapy.