The present disclosure provides compositions comprising an antisense oligonucleotide and one or more excipients that modulates viscosity, turbidity or both viscosity and turbidity. In certain embodiments, compositions comprising an antisense oligonucleotide and one or more excipients having low viscosity are provided. In certain embodiments, compositions comprising an antisense oligonucleotide and one or more excipients having low turbidity are provided. In certain embodiments, pharmaceutical compositions comprising an antisense oligonucleotide and one or more excipients having low viscosity and turbidity are provided.

Provided herein are double-stranded nucleic acid inhibitor molecules having a sense strand with a stem loop structure and an antisense strand, where the stem portion of the stem loop structure contains one or more T.sub.m-increasing nucleotides. Also provided are methods and compositions for reducing target gene expression and methods and compositions for treating a disease of interest.

A method of reducing the level of a transcription product in a cell comprising contacting with the cell a composition comprising a double-stranded nucleic acid complex comprising a first nucleic acid strand annealed to a second nucleic acid strand, wherein: (i) the first nucleic acid strand hybridizes to the transcription product and comprises (a) a region consisting of at least 4 consecutive nucleotides that are recognized by RNase H when the strand is hybridized to the transcription product, (b) one or more nucleotide analogs located on 5 terminal side of the region, (c) one or more nucleotide analogs located on 3 terminal side of the region and (d) a total number of nucleotides and nucleotide analogs ranging from 8 to 35 nucleotides and (ii) the second nucleic acid strand comprises (a) nucleotides and optionally nucleotide analogs and (b) at least 4 consecutive RNA nucleotides.

A method of reducing the level of a transcription product in a cell comprising contacting with the cell a composition comprising a double-stranded nucleic acid complex comprising a first nucleic acid strand annealed to a second nucleic acid strand, wherein: (i) the first nucleic acid strand hybridizes to the transcription product and comprises (a) a region consisting of at least 4 consecutive nucleotides that are recognized by RNase H when the strand is hybridized to the transcription product, (b) one or more nucleotide analogs located on 5 terminal side of the region, (c) one or more nucleotide analogs located on 3 terminal side of the region and (d) a total number of nucleotides and nucleotide analogs ranging from 8 to 35 nucleotides and (ii) the second nucleic acid strand comprises (a) nucleotides and optionally nucleotide analogs and (b) at least 4 consecutive RNA nucleotides.

Disclosed herein are high Tm RNA nanostructures that can be composed of one or more modules or motifs to build RNA nanostructures with or without layers. The RNA nanostructures can have a core domain and three or more double-stranded arms and formulations thereof to conjugate high copy numbers of therapeutics, pH responsive or enzyme cleavable drug cargo. Also described herein is a design strategy for generation of synthetic RNA oligonucleotides that can self assemble into highly thermostable RNA structures. Also described herein are uses of the RNA nanostructures described herein.

One aspect of the present invention relates to double-stranded RNA (dsRNA) agent capable of inhibiting the expression of a target gene. The sense strand of the dsRNA agent comprises at least one thermally destabilizing nucleotide, and at least one said thermally destabilizing nucleotide occurring at a site opposite to the seed region (positions 2-8) of the antisense strand; and the antisense strand of the dsRNA agent comprises at least two modified nucleotides that provide the nucleotide a steric bulk that is less than or equal to the steric bulk of a 2-OMe modification, wherein said modified nucleotides are separated by 11 nucleotides in length. Other aspects of the invention relates to pharmaceutical compositions comprising these dsRNA agents suitable for therapeutic use, and methods of inhibiting the expression of a target gene by administering these dsRNA agents, e.g., for the treatment of various disease conditions.

One aspect of the present invention relates to double-stranded RNA (dsRNA) agent capable of inhibiting the expression of a target gene. The sense strand of the dsRNA agent comprises at least one thermally destabilizing nucleotide, and at least one said thermally destabilizing nucleotide occurring at a site opposite to the seed region (positions 2-8) of the antisense strand; and the antisense strand of the dsRNA agent comprises at least two modified nucleotides that provide the nucleotide a steric bulk that is less than or equal to the steric bulk of a 2-OMe modification, wherein said modified nucleotides are separated by 11 nucleotides in length. Other aspects of the invention relates to pharmaceutical compositions comprising these dsRNA agents suitable for therapeutic use, and methods of inhibiting the expression of a target gene by administering these dsRNA agents, e.g., for the treatment of various disease conditions.

In some embodiments, disclosed herein are oligomeric compounds which include one or more tricyclo-deoxyribonucleic acid (tc-DNA) nucleosides and one or more 2-modified ribonucleic acid (2-modified-RNA) nucleosides, and which optionally also include one or more non-nucleotides, each of which is joined by a plurality of internucleoside linkages, including pharmaceutical compositions and methods of using the pharmaceutical compositions for the treatment of diseases including Duchenne muscular dystrophy treatment of familial dysautonomia, spinal muscular atrophy, ataxia telangiectasia, congenital disorder of glycosylation, fronto-temporal dementia, Parkinsonism linked to chromosome 17, Niemann-Pick disease type C, neurofibromatosis type 1, neurofibromatosis type 2, megalencephalic leukoencephalopathy with subcortical cysts type 1, Pelizaeus-Merzbacher disease, Pompe disease, myotonic dystrophy type 2 (DM2 or proximal myotonic myopathy), and myotonic dystrophy type 1 (DM1 or Steinert disease).

The invention proves an oligonucleotide comprising one or more carboxylated 2-amino-LNA nucleotide units. The invention also provides a method of transfecting cells with the oligonucleotide, a method of treating a human or animal by therapy using the oligonucleotide, and a pharmaceutical composition comprising the oligonucleotide.

A method of reducing the level of a transcription product in a cell comprising contacting with the cell a composition comprising a double-stranded nucleic acid complex comprising a first nucleic acid strand annealed to a second nucleic acid strand, wherein: (i) the first nucleic acid strand hybridizes to the transcription product and comprises (a) a region consisting of at least 4 consecutive nucleotides that are recognized by RNase H when the strand is hybridized to the transcription product, (b) one or more nucleotide analogs located on 5 terminal side of the region, (c) one or more nucleotide analogs located on 3 terminal side of the region and (d) a total number of nucleotides and nucleotide analogs ranging from 8 to 35 nucleotides and (ii) the second nucleic acid strand comprises (a) nucleotides and optionally nucleotide analogs and (b) at least 4 consecutive RNA nucleotides.