A method of treating neurodegenerative diseases or disorders, especially Parkinson's disease and a method of inducing neural stem cells from peripheral blood mononuclear cells. The induced neural stem cells can express neural stem cell-related genes and differentiate into neurons, astrocytes and oligodendrocytes. The dopaminergic precursors derived from the induced neural stem cells are transplanted into the striatum of the PD mouse models without any sign of tumorigenesis, thereby improving the behaviors of the PD mouse models and slowing down the progression of Parkinson's disease.