Lipid-siRNA Conjugate Accesses a Perivascular Transport Mechanism and Achieves Widespread and Durable Knockdown in the Central Nervous System

Short-interfering RNA (siRNA) has gained significant interest for treatment of neurological diseases by providing the capacity to achieve sustained inhibition of nearly any gene target. Yet, achieving efficacious drug delivery throughout deep brain structures of the CNS remains a considerable hurdle. We herein describe a lipid-siRNA conjugate that, following delivery into the cerebrospinal fluid (CSF), is transported effectively through perivascular spaces, enabling broad dispersion within CSF compartments and through the CNS parenchyma. We provide a detailed examination of the temporal kinetics of gene silencing, highlighting potent knockdown for up to five months from a single injection without detectable toxicity. Single-cell RNA sequencing further demonstrates gene silencing activity across diverse cell populations in the parenchyma and at brain borders, which may provide new avenues for neurological disease-modifying therapies. ### Competing Interest Statement The authors have declared no competing interest. Raw sequencing data and processed Seurat objects are available at Array Express under accession number E-MTAB-13964. Code for reproducing the single-cell RNA sequencing analysis is available upon request.