Enhancing the efficiency of direct reprogramming of human primary fibroblasts into dopaminergic neuron-like cells through p53 suppression.

Dopaminergic (DA) neuron-like cells obtained through direct reprogramming of primary human fibroblasts offer exciting opportunities for treatment of Parkinson's disease. A significant obstacle is the low efficiency of conversion during the reprogramming process. Here, we demonstrate that the suppression of p53 significantly enhances the efficiency of transcription factor-mediated conversion of human fibroblasts into functional dopaminergic neurons. In particular, blocking p53 activity using a dominant-negative p53 (p53-DN) in IMR90 cells increases the conversion efficiency by 5-20 fold. The induced DA neuron-like cells exhibit dopamine neuron-specific gene expression, significant dopamine uptake and production capacities, and enables symptomatic relief in a rat Parkinson's disease model. Taken together, our findings suggest that p53 is a critical barrier in direct reprogramming of fibroblast into dopaminergic neurons.