392. Evaluating Promoter Regulated Dopaminergic Neuron Targeting with AAV9 Delivered To the Neonatal Mouse

Abstract

Parkinson's disease (PD) is a progressive neurodegenerative disease due to profound degeneration of mid-brain dopaminergic (DA) nigrostriatal neurons. Childhood onset monogenic forms of PD and DA neurotransmitter disorders are increasingly recognised where current medical treatments are ineffective and gene therapy may have significant therapeutic impact. These disorders highlight that gene delivery and expression needs vary and the challenge is to target the DA neurons that require the therapeutic transgene. Adeno-associated virus (AAV) achieves global central nervous system delivery (CNS) following both intracerebroventricular (IC) and intravenous (IV) delivery in neonatal mice. We evaluated the effect of promoter choice on DA neuronal expression following these modes of administration. Using AAV2/9 serotype vectors with different promoters [Tyrosine hydroxylase (rTH), beta glucuronidase B (GUSB), Synapsin (hSyn) with CMV control] expressing green fluorescent protein (GFP) we assessed the brain regions targeted following IC and IV injection to P0 neonatal mice. Transduction profiles were evaluated through direct stereoscopic fluorescence and free floating immunohistochemistry with thresholding intensities at P35. Co-localisation with TH positive neurons was performed with fluorescence immunohistochemistry and confocal microscopy. The most extensive intracranial transduction was achieved with hSyn, followed by GUSB and minimal with rTH promoter. IC delivery demonstrated superior widespread intracranial transduction than IV delivery. TH positive neurons in the substantia nigra were transduced with: rTH promoter (IC =4%, IV=20%), GUSB (IC =6.9%, IV= 0%) hSyn (IC=0%, IV= 24%). Here we observe evidence that targeting mid-brain DA neurons is influenced by both delivery method and promoter following administration to the neonatal mouse brain.