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NON-INVASIVE AND TARGETED VIRAL VECTOR-MEDIATED NEUROTROPHIC FACTOR DELIVERY TO THE BRAIN WITH THERANOSTIC ULTRASOUND INDUCES NEURORESTORATIVE EFFECTS IN A PARKINSON’S DISEASE MOUSE MODEL
Abstract
Aims
To induce restoration of degenerated dopaminergic neurons with non-invasive viral vector-mediated neurotrophic factor delivery achieved by targeted blood-brain barrier opening (BBBO) with theranostic ultrasound (ThUS) in vivo.
Methods
BBBO with focused ultrasound in conjunction with systemically administered microbubbles is a safe and reversible technique for targeted drug delivery to the brain, providing a non-invasive alternative to direct intracranial injection. A novel configuration for transcranial BBBO developed by our group, called ThUS, was used to perform simultaneous bilateral delivery of AAV encoding human neurturin (NTRN) to the murine substantia nigra (Fig. 1A-B).
To induce neurodegeneration, 16-week-old male C57BL/6J mice (Charles River, Kingston, NY) underwent a sub-acute dosing scheme of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) consisting of daily intraperitoneal injections (30 mg/kg) for 5 days. After a 21-day period of neurodegeneration, mice were anesthetized with isoflurane anesthesia and underwent 2 minutes of ThUS-mediated BBBO immediately after intravenous co-injection of AAV9-hSynapsin-hNTRN (Vector Biolabs) and house-made polydisperse microbubbles (8e8 microbubbles/mL). 90 days post-BBBO, mice were sacrificed for histology with tyrosine hydroxylase (TH) staining (Fig. 1C).
Results
Quantification of GFP fluorescence area revealed a significant ~96% increase in dendritic network density in the substantia nigra pars reticulata (SNr) in MPTP mice which received ThUS+AAV (Fig. 2A-C). No significant differences in SNr dendrite density were observed between groups receiving either ThUS or AAV alone compared to MPTP mice which did not receive treatment intervention (Fig. 2C). A 2-fold increase in cell body density within the pars compacta (SNc) was observed in MPTP mice treated with ThUS+AAV relative to MPTP mice alone (Fig. 2D).
Conclusions
ThUS-mediated AAV-hNTRN delivery induced histological evidence of neurorestoration in Parkinsonian mice, demonstrating the potential for a more effective and non-invasive option for gene delivery in PD treatment.