Direct CNS delivery of siRNA mediates robust silencing in oligodendrocytes.
The most significant challenge remaining in the development of small interfering RNAs (siRNAs) as a new class of therapeutic drugs is successful delivery in vivo. The majority of reported studies describing delivery of siRNA or short hairpin RNA (shRNA) to the central nervous system (CNS) have focused on RNA interference (RNAi) in neurons. Here we show direct CNS delivery of siRNA to a different cell type-oligodendrocytes-using convection-enhanced delivery, and demonstrate robust silencing of an endogenous oligodendrocyte-specific gene, 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) with siRNA formulated in saline. The silencing is not sequence-dependent as several different siRNAs are effective in inhibiting target gene expression. Furthermore, we show that CNPase mRNA reduction is dose-dependent, durable for up to 1 week, and mediated by an RNAi mechanism. Increasing the flow rate of siRNA infusion increased the distribution of mRNA suppression to encompass white matter regions distant from the infusion site. Finally, we demonstrate suppression of CNPase mRNA in the nonhuman primate CNS. Taken together, these results show for the first time robust RNAi within oligodendrocytes in vivo and demonstrate the important potential of siRNAs in the treatment of CNS disorders involving oligodendrocyte pathology.
Querbes
William
W
Alnylam Pharmaceuticals, Inc., Cambridge, Massachusetts 02142, USA. wquerbes@alnylam.com
Ge
Pei
P
Zhang
Wenjun
W
Fan
Yupeng
Y
Costigan
Jason
J
Charisse
Klaus
K
Maier
Martin
M
Nechev
Lubomir
L
Manoharan
Muthiah
M
Kotelianski
Victor
V
Sah
Dinah W Y
DW
D000818:Animals; D001483:Base Sequence; D002490:Central Nervous System / Q000187:drug effects* / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D009836:Oligodendroglia / Q000187:drug effects* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D034741:RNA, Small Interfering