Exosome-mediated Delivery of Hydrophobically Modified siRNA for Huntingtin mRNA Silencing

Delivery represents a significant barrier to the clinical advancement of oligonucleotide therapeutics for the treatment of neurological disorders, such as Huntington\u27s disease. Small, endogenous vesicles known as exosomes have the potential to act as oligonucleotide delivery vehicles, but robust and scalable methods for loading RNA therapeutic cargo into exosomes are lacking. Here, we show that hydrophobically modified small interfering RNAs (hsiRNAs) efficiently load into exosomes upon co-incubation, without altering vesicle size distribution or integrity. Exosomes loaded with hsiRNAs targeting Huntingtin mRNA were efficiently internalized by mouse primary cortical neurons and promoted dose-dependent silencing of Huntingtin mRNA and protein. Unilateral infusion of hsiRNA-loaded exosomes, but not hsiRNAs alone, into mouse striatum resulted in bilateral oligonucleotide distribution and statistically significant bilateral silencing of up to 35% of Huntingtin mRNA. The broad distribution and efficacy of hsiRNA-loaded exosomes delivered to brain is expected to advance the development of therapies for the treatment of Huntington\u27s disease and other neurodegenerative disorders

Hydrophobically Modified siRNAs Silence Huntingtin mRNA in Primary Neurons and Mouse Brain

Applications of RNA interference for neuroscience research have been limited by a lack of simple and efficient methods to deliver oligonucleotides to primary neurons in culture and to the brain. Here, we show that primary neurons rapidly internalize hydrophobically modified siRNAs (hsiRNAs) added directly to the culture medium without lipid formulation. We identify functional hsiRNAs targeting the mRNA of huntingtin, the mutation of which is responsible for Huntington\u27s disease, and show that direct uptake in neurons induces potent and specific silencing in vitro. Moreover, a single injection of unformulated hsiRNA into mouse brain silences Htt mRNA with minimal neuronal toxicity. Thus, hsiRNAs embody a class of therapeutic oligonucleotides that enable simple and straightforward functional studies of genes involved in neuronal biology and neurodegenerative disorders in a native biological context

Carbonate sedimentology of the early Precambrian Hamersley Group of Western Australia

The early Precambrian Hamersley Group of Western Australia contains both major and minor occurrences of well-preserved carbonate sedimentary rock. The Carawine Dolomite and the middle or Paraburdoo Member of the Wittenoom Formation are the two most extensive occurrences. The Carawine Dolomite is restricted to the eastern part of the Hamersley Basin and contains abundant stromatolites, oncolites, and wave ripples, as well as local occurrences of evaporite crystal pseudomorphs and oolitic to pisolitic textures. These carbonate strata were deposited in a shallow-water paleoenvironment herein referred to as the Carawine Platform. In contrast, the Wittenoom Formation is restricted to the centraland western parts of the Hamersley Basin, and such shallow-water features are entirely absent from its carbonate strata. These strata consist largely of thinly laminated lutite, but also include some thin carbonate turbidites. The carbonate sedimentary rocks of the Wittenoom Formation, as well as some in the Carawine Dolomite which display similar characteristics, are therefore interpreted as sediments that were deposited off-platform in deeper-water paleoenvironments. Paleocurrent, thickness, and grain size trends of the carbonate turbidites indicate they were deposited by paleoflows moving south and west. Even though the Carawine Dolomite lies to the northeast of the Wittenoom Formation, stratigraphic correlations using a newly recognized marker bed of probable impact origin suggest that the carbonate strata of the Carawine Dolomite are younger than the Paraburdoo Member of the Wittenoom Formation. If true, the Carawine Platform could not have been a source of sediment for most of the carbonate sedimentary rocks in the Wittenoom Formation, but it may havebeen the sediment source for similar carbonate turbidites in younger formations such as the Mt. McRae Shale and the Dales Gorge Member of the Brockman Iron Formation. This, in turn, suggests that carbonate sediments were accumulating in the shallower parts of the Hamersley Basin while some of the BIFs were being deposited simultaneously in the deeper parts