Generation of Functional Dopaminergic Neurons from Reprogramming Fibroblasts by Nonviral-based Mesoporous Silica Nanoparticles

Direct-lineage conversion of the somatic cell by reprogramming, in which mature cells were fully converted into a variety of other cell types bypassing an intermediate pluripotent state, is a promising regenerative medicine approach. Due to the risk of tumorigenesis by viral methods, a non-viral carrier for the delivery of reprogramming factors is very desirable. This study utilized the mesoporous silica nanoparticles (MSNs) as a non-viral delivery system for transduction of the three key factors to achieve conversion of mouse fibroblasts (MFs) into functional dopaminergic neuron-like cells (denoted as fDA-neurons). At the same time, a neurogenesis inducer, ISX-9, was co-delivered with the MSNs to promote the direct conversion of neuron-like cells. Good transfection efficiency of plasmid@MSN allowed repeated dosing to maintain high exogenous gene expression analyzed by qPCR and the changes in neural function markers were monitored. To further validate the dopaminergic function and the electrophysiological properties of fDA-neurons, the results of ELISA assay showed the high levels of secreted-dopamine in the conditional medium and rich Na⁺/K⁺-channels were observed in the fDA-neurons on Day 22. The results demonstrated that MSN nanocarrier is effective in delivering the reprogramming factors for the conversion of functional dopaminergic neurons from adult somatic cells.