Compositions and methods for efficacious and safe delivery of sirna using specific chitosan-based nanocomplexes

Abstract

There is disclosed a composition and a method for the efficient delivery of a therapeutic RNAi-inducing nucleic acid to cells both in vitro and in vivo through specific formulations of a non viral delivery system using chitosans. Particularly, the composition contains a nucleic acid and a specific chitosan that has the following physico-chemical properties: a number-average molecular weight between 5 kDa and 200 kDa, a degree of deacetylation between 80% and 95% and a chitosan amine to nucleic acid phosphate ratio below 20.

What is claimed is: 
     
         1 . An in vivo nucleic acid delivery nanoparticle, the nanoparticle comprising an RNAi-inducing nucleic acid molecule and a chitosan, wherein the RNAi-inducing nucleic acid molecule includes a short interfering RNA (siRNA) or a short hairpin RNA (shRNA), wherein the chitosan has a molecular weight (M n ) selected in the range of 5 kDa to 200 kDa and a degree of deacetylation (DDA) selected in the range of 80% to 95%, wherein the chitosan amine to nucleic acid phosphate ratio (N:P) is below 20, and wherein the combination of Mn, DDA and N:P ratio is such that when introduced into a host, the nanoparticle causes the RNAi-inducing nucleic acid molecule to be delivered into cells. 
     
     
         2 . The nanoparticle according to  claim 1 , wherein the M n  is selected in the range of 5 to 15 kDa. 
     
     
         3 . The nanoparticle according to  claim 1 , wherein the DDA is selected in the range of 90 to 95%. 
     
     
         4 . The nanoparticle according to  claim 1 , wherein the N:P ratio is selected in the range of 2 to 10. 
     
     
         5 . The nanoparticle according to  claim 1 , wherein the chitosan comprises block distribution of acetyl groups or a chemical modification. 
     
     
         6 . The nanoparticle according to  claim 1 , wherein said chitosan has a polydispersity between 1.0 and 7.0. 
     
     
         7 . The nanoparticle according to  claim 1 , wherein the RNAi-inducing nucleic acid molecule is chemically modified either on the sugar backbone, phosphate backbone and/or the nucleotide base ring. 
     
     
         8 . The nanoparticle according to  claim 1 , wherein the M n  is selected in the range of 5 to 15 kDa, the DDA is selected in the range of 90 to 95% and the N:P ratio is selected in the range of 2 to 10. 
     
     
         9 . The nanoparticle according to  claim 1 , wherein the nanoparticle has a size below 200 nm. 
     
     
         10 . The nanoparticle according to  claim 1 , wherein the RNAi-inducing nucleic acid molecule is a siRNA. 
     
     
         11 . The nanoparticle according to  claim 10 , wherein the M n  is selected in the range of 5 to 15 kDa, the DDA is selected in the range of 90 to 95% and the N:P ratio is selected in the range of 2 to 10. 
     
     
         12 . The nanoparticle according to  claim 1 , wherein the M n  is 10 kDa, the DDA is 92% and the N:P ratio is 5. 
     
     
         13 . The nanoparticle according to  claim 1 , having a spherical shape. 
     
     
         14 . A composition comprising the nanoparticle according to  claim 1  and a pharmaceutical acceptable excipient or carrier. 
     
     
         15 . The composition according to  claim 14 , which is formulated as a dried powder. 
     
     
         16 . The composition according to  claim 14 , which is formulated at an injection dose of about 1 mg/kg of the RNAi-inducing nucleic acid molecule. 
     
     
         17 . The composition according to  claim 14 , which is formulated for parenteral administration. 
     
     
         18 . The composition according to  claim 14 , wherein the RNAi-inducing nucleic acid molecule is a siRNA. 
     
     
         19 . The composition according to  claim 18 , wherein the M n  is selected in the range of 5 to 15 kDa, the DDA is selected in the range of 90 to 95% and the N:P ratio is selected in the range of 2 to 10. 
     
     
         20 . The composition according to  claim 14 , wherein the nanoparticle has a size below 200 nm.