ABSTRACT
Non-human primates (NHPs) are a preferred animal model for optimizing adeno-associated virus (AAV)-mediated CNS gene delivery protocols before clinical trials. In spite of its inherent appeal, it is challenging to compare different serotypes, delivery routes, and disease indications in a well-powered, comprehensive, multigroup NHP experiment. Here, a multiplex barcode recombinant AAV (rAAV) vector-tracing strategy has been applied to a systemic analysis of 29 distinct, wild-type (WT), AAV natural isolates and engineered capsids in the CNS of eight macaques. The report describes distribution of each capsid in 15 areas of the macaques' CNS after intraparenchymal (putamen) injection, or cerebrospinal fluid (CSF)-mediated administration routes (intracisternal, intrathecal, or intracerebroventricular). To trace the vector biodistribution (viral DNA) and targeted tissues transduction (viral mRNA) of each capsid in each of the analyzed CNS areas, quantitative next-generation sequencing analysis, assisted by the digital-droplet PCR technology, was used. The report describes the most efficient AAV capsid variants targeting specific CNS areas after each route of administration using the direct side-by-side comparison of WT AAV isolates and a new generation of rationally designed capsids. The newly developed bioinformatics and visualization algorithms, applicable to the comparative analysis of several mammalian brain models, have been developed and made available in the public domain.
Subject(s)
Capsid Proteins/genetics , Central Nervous System/chemistry , Dependovirus/physiology , Genetic Vectors/administration & dosage , Algorithms , Animals , Central Nervous System/virology , DNA, Viral/genetics , Databases, Genetic , Dependovirus/genetics , Drug Administration Routes , High-Throughput Nucleotide Sequencing , Primates , RNA, Messenger/genetics , RNA, Viral/genetics , Tissue Distribution , Transduction, GeneticABSTRACT
OBJECTIVE: Patients with dementia with Lewy bodies (DLB) often experience visual hallucinations, which are related to decreased quality of life for patients and increased caregiver distress. The pathologic changes that contribute to visual hallucinations are not known, but several hypotheses implicate deficient attentional processing. The superior colliculus has a role in visual attention and planning eye movements and has been directly implicated in several models of visual hallucinations. Therefore, the present study sought to identify neurodegenerative changes that may contribute to hallucinations in DLB. METHODS: Postmortem superior colliculus tissue from 13 comparison, 10 DLB, and 10 Alzheimer disease (AD) cases was evaluated using quantitative neuropathologic methods. RESULTS: α-Synuclein and tau deposition were more severe in deeper layers of the superior colliculus. DLB cases had neuronal density reductions in the stratum griseum intermedium, an important structure in directing attention toward visual targets. In contrast, neuronal density was reduced in all laminae of the superior colliculus in AD. CONCLUSION: These findings suggest that regions involved in directing attention toward visual targets are subject to neurodegenerative changes in DLB. Considering several hypotheses of visual hallucinations implicating dysfunctional attention toward external stimuli, these findings may provide evidence of pathologic changes that contribute to the manifestation of visual hallucinations in DLB.