The therapeutic potential of stem cells and progenitor cells for the treatment of Parkinson's disease.

Parkinson's disease (PD) is the second most common neurodegenerative disorder. It is usually seen in those above 50 years old. Current medical treatments only provide symptomatic relief but cannot cure the disease. There are claims that PD can be cured by stem cell transplant. The present study is aimed to assess the clinical potency and safety of stem cell in treating PD. A total of eleven articles were included for analysis, with four randomised control trials (RCTs), five non-RCTs and 2 follow up studies. All the four non-RCTs showed improvement of Unified Parkinson's Disease Rating Scale with no adverse events. However, results from RCTs showed no significant differences in the rating score among the transplant group and the Sham surgery group. The secondary analysis of one study showed a significant improvement of the rating score in those patients aged 60 and younger. Transplant group also associated with an overall higher incidence of adverse events. In conclusion, the RCTs and non-RCTs produced opposite results. When the studies were performed as non-RCTs in small number of patients, they showed promising result in the patients. It could say that currently the use of stem cell/progenitor cells in treating PD need much research despite having the implanted stem cell to be able to survive and integrated. The survival of implanted dopamine neurons in the striatum, however, does not indicate a success in correcting PD symptoms. Further investigations will shed light on the application and mechanism of action of stem cells in treating PD. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at 10.1007/s13770-016-9093-2 and is accessible for authorized users.