RESUMO
Neurotensin-polyplex nanoparticles provide efficient gene transfection of nigral dopaminergic neurons when intracerebrally injected in preclinical trials of Parkinson's disease because they do not cross the blood-brain barrier (BBB). Therefore, this study aimed to open BBB with focused ultrasound (FUS) on the substantia nigra to attain systemic and intranasal transfections and evaluate its detrimental effect in rats. Systemically injected Evans Blue showed that a two-pulse FUS opened the nigral BBB. Accordingly, 35 µL of neurotensin-polyplex nanoparticles encompassing the green fluorescent protein plasmid (79.6 nm mean size and + 1.3 mV Zeta-potential) caused its expression in tyrosine hydroxylase(+) cells (dopaminergic neurons) of both substantiae nigrae upon delivery via internal carotid artery, retro-orbital venous sinus, or nasal mucosa 30 min after FUS. The intracarotid delivery yielded the highest transgene expression, followed by intranasal and venous administration. However, FUS caused neuroinflammation displayed by infiltrated lymphocytes (positive to cluster of differentiation 45), activated microglia (positive to ionized calcium-binding adaptor molecule 1), neurotoxic A1 astrocytes (positive to glial fibrillary acidic protein and complement component 3), and neurotrophic A2 astrocytes (positive to glial fibrillary acidic protein and S100 calcium-binding protein A10), that ended 15 days after FUS. Dopaminergic neurons and axonal projections decreased but recuperated basal values on day 15 after transfection, correlating with a decrease and recovery of locomotor behavior. In conclusion, FUS caused transient neuroinflammation and reversible neuronal affection but allowed systemic and intranasal transfection of dopaminergic neurons in both substantiae nigrae. Therefore, FUS could advance neurotensin-polyplex nanotechnology to clinical trials for Parkinson's disease.
RESUMO
JOURNAL/nrgr/04.03/01300535-202409000-00039/figure1/v/2024-01-16T170235Z/r/image-tiff Parkinsonism by unilateral, intranigral ß-sitosterol ß-D-glucoside administration in rats is distinguished in that the α-synuclein insult begins unilaterally but spreads bilaterally and increases in severity over time, thus replicating several clinical features of Parkinson's disease, a typical α-synucleinopathy. As Nurr1 represses α-synuclein, we evaluated whether unilateral transfected of rNurr1-V5 transgene via neurotensin-polyplex to the substantia nigra on day 30 after unilateral ß-sitosterol ß-D-glucoside lesion could affect bilateral neuropathology and sensorimotor deficits on day 30 post-transfection. This study found that rNurr1-V5 expression but not that of the green fluorescent protein (the negative control) reduced ß-sitosterol ß-D-glucoside-induced neuropathology. Accordingly, a bilateral increase in tyrosine hydroxylase-positive cells and arborization occurred in the substantia nigra and increased tyrosine hydroxylase-positive ramifications in the striatum. In addition, tyrosine hydroxylase-positive cells displayed less senescence marker ß-galactosidase and more neuron-cytoskeleton marker ßIII-tubulin and brain-derived neurotrophic factor. A significant decrease in activated microglia (positive to ionized calcium-binding adaptor molecule 1) and neurotoxic astrocytes (positive to glial fibrillary acidic protein and complement component 3) and increased neurotrophic astrocytes (positive to glial fibrillary acidic protein and S100 calcium-binding protein A10) also occurred in the substantia nigra. These effects followed the bilateral reduction in α-synuclein aggregates in the nigrostriatal system, improving sensorimotor behavior. Our results show that unilateral rNurr1-V5 transgene expression in nigral dopaminergic neurons mitigates bilateral neurodegeneration (senescence and loss of neuron-cytoskeleton and tyrosine hydroxylase-positive cells), neuroinflammation (activated microglia, neurotoxic astrocytes), α-synuclein aggregation, and sensorimotor deficits. Increased neurotrophic astrocytes and brain-derived neurotrophic factor can mediate the rNurr1-V5 effect, supporting its potential clinical use in the treatment of Parkinson's disease.