Cerebral dopamine neurotrophic factor transfection in dopamine neurons using neurotensin-polyplex nanoparticles reverses 6-hydroxydopamine-induced nigrostriatal neurodegeneration

Overexpression of neurotrophic factors in nigral dopamine neurons is a promising approach to reverse neurodegeneration of the nigrostriatal dopamine system,a hallmark in Parkinson's disease.The human cerebral dopamine neurotrophic factor(h CDNF)has recently emerged as a strong candidate for Parkinson's disease therapy.This study shows that h CDNF expression in dopamine neurons using the neurotensinpolyplex nanoparticle system reverses 6-hydroxydopamine-induced morphological,biochemical,and behavioral alterations.Three independent electron microscopy techniques showed that the neurotensin-polyplex nanoparticles containing the h CDNF gene,ranging in size from 20 to 150 nm,enabled the expression of a secretable h CDNF in vitro.Their injection in the substantia nigra compacta on day 21 after the 6-hydroxydopamine lesion resulted in detectable h CDNF in dopamine neurons,whose levels remained constant throughout the study in the substantia nigra compacta and striatum.Compared with the lesioned group,tyrosine hydroxylase-positive(TH⁺)nigral cell population and TH+fiber density rose in the substantia nigra compacta and striatum after h CDNF transfection.An increase inβIII-tubulin and growth-associated protein 43 phospho-S41(GAP43 p)followed TH⁺cell recovery,as well as dopamine and its catabolite levels.Partial reversal(80%)of drugactivated circling behavior and full recovery of spontaneous motor and non-motor behavior were achieved.Brain-derived neurotrophic factor recovery in dopamine neurons that also occurred suggests its participation in the neurotrophic effects.These findings support the potential of nanoparticle-mediated h CDNF gene delivery to develop a disease-modifying treatment against Parkinson's disease.The Institutional Animal Care and Use Committee of Centro de Investigación y de Estudios Avanzados approved our experimental procedures for animal use(authorization No.162-15)on June 9,2019.