Transvascular Delivery of Hydrophobically Modified siRNAs: Gene Silencing in the Rat Brain upon Disruption of the Blood-Brain Barrier

• Published in: Molecular therapy Vol. 26; no. 11; pp. 2580 - 2591
• Main Authors: Godinho, Bruno M.D.C., Henninger, Nils, Bouley, James, Alterman, Julia F., Haraszti, Reka A., Gilbert, James W., Sapp, Ellen, Coles, Andrew H., Biscans, Annabelle, Nikan, Mehran, Echeverria, Dimas, DiFiglia, Marian, Aronin, Neil, Khvorova, Anastasia
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 07-11-2018; Elsevier Limited; American Society of Gene & Cell Therapy
• Subjects: Astrocytes; Blood-brain barrier; Carotid arteries; Cortex (motor); Cortex (somatosensory); Fatty acids; Gene silencing; Gliosis; hyperosmolar mannitol; Immunoglobulins; Internalization; intracarotid injection; Mannitol; Membrane permeability; Membranes; mRNA; Neostriatum; Neurological diseases; Neurotoxicity; Oligonucleotides; Original; osmotic disruption; Parenchyma; Permeability; Phosphocholine; RNA interference; siRNA; Studies; Thalamus; therapeutic oligonucleotide; Veins & arteries; osmotic disruption; hyperosmolar mannitol; RNA interference; intracarotid injection; therapeutic oligonucleotide
• ISSN: 1525-0016; 1525-0024
• DOI: 10.1016/j.ymthe.2018.08.005

Effective transvascular delivery of therapeutic oligonucleotides to the brain presents a major hurdle to the development of gene silencing technologies for treatment of genetically defined neurological disorders. Distribution to the brain after systemic administrations is hampered by the low permeability of the blood-brain barrier (BBB) and the rapid clearance kinetics of these drugs from the blood. Here we show that transient osmotic disruption of the BBB enables transvascular delivery of hydrophobically modified small interfering RNA (hsiRNA) to the rat brain. Intracarotid administration of 25% mannitol and hsiRNA conjugated to phosphocholine-docosahexanoic acid (PC-DHA) resulted in broad ipsilateral distribution of PC-DHA-hsiRNAs in the brain. PC-DHA conjugation enables hsiRNA retention in the parenchyma proximal to the brain vasculature and enabled active internalization by neurons and astrocytes. Moreover, transvascular delivery of PC-DHA-hsiRNAs effected Htt mRNA silencing in the striatum (55%), hippocampus (51%), somatosensory cortex (52%), motor cortex (37%), and thalamus (33%) 1 week after administration. Aside from mild gliosis induced by osmotic disruption of the BBB, transvascular delivery of PC-DHA-hsiRNAs was not associated with neurotoxicity. Together, these findings provide proof-of-concept that temporary disruption of the BBB is an effective strategy for the delivery of therapeutic oligonucleotides to the brain.
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Godinho et al. demonstrate the utility of transient blood-brain barrier (BBB) disruption using hyperosmolar mannitol as a delivery strategy for fully modified lipid-conjugated hydrophobic siRNAs (hsiRNAs). Phosphocholine-docosahexanoic acid (PC-DHA)-conjugated hsiRNAs broadly distribute in the brain after BBB disruption, enabling potent gene silencing without major neurotoxicity.