Neurodegenerative disease is directed to a range of conditions which primarily affect the neurons in the human brain. Parkinson's disease (PD) is the second most common neurodegenerative disease with physiological manifestations including tremors, bradykinesia, abnormal postural reflexes, rigidity and akinesia. It results primarily from the death of dopaminergic (DA) neurons in the substantia nigra. Current therapies for PD mainly provide symptomatic improvement by replacing neurotransmitters or controlling their metabolism to restore their imbalance. Since these therapies are not altering the underlying disease process, they usually have little or no impact on disease progression.