Non-viral gene delivery system

Abstract

The present invention concerns a composition comprising complexes of cationic chitosan oligomers derived from the cationic polysaccharide chitosan, wherein said cationic oligomers contain a weight fraction of less than 20% of oligomers with a Degree of Polymerization (DP)<10 in addition to a weight fraction of less than 20% with DP>50, and a nucleic acid. These compositions comprising well-defined cationic chitosan oligomers having a certain distribution of chain lengths, and nucleic acid are advantageous to achieve delivery of the nucleic acid into cells of a selected tissue, and to obtain in vivo expression of the desired molecules encoded for by the nucleic acid.

1 . A composition comprising complexes of: 
 (a) cationic chitosan oligomers derived from the cationic polysaccharide chitosan wherein said cationic oligomers contain a weight fraction of less than 20% of oligomers with a Degree of Polymerization (DP)<10 in addition to a weight fraction of less than 20% with DP>50; and    (b) a nucleic acid.    
     
     
         2 . The composition of  claim 1 , wherein said cationic chitosan oligomers are obtained from chitosan using chemical or enzymatic methods.  
     
     
         3 . The composition of  claim 1 , wherein said cationic oligomers contain preferably a weight fraction of less than 20% of oligomers with DP<12 in addition to a weight fraction of less than 20% with a DP>40 and most preferably a weight fraction of less than 20% of oligomers with DP<15 in addition to a weight fraction of less than 20% with a DP>30.  
     
     
         4 . The composition of  claim 1 , where the fraction of N-acetylated units (F A ) of said chitosan oligomers is less than 0.60, preferably less than 0.35, more preferably less than 0.1 and most preferably less than 0.01.  
     
     
         5 . The composition of  claim 1 , wherein said composition essentially has a net positive charge ratio.  
     
     
         6 . The composition of  claim 1  wherein said chitosan oligomers are derivatized with targeting ligands and stabilizing agents.  
     
     
         7 . The composition of  claim 1 , wherein said complexes comprise a coding sequence that will express its function when said nucleic acid is introduced into a host cell.  
     
     
         8 . The composition of  claim 7 , wherein said nucleic acid is selected from the group consisting of DNA and RNA molecules.  
     
     
         9 . The composition of  claim 8 , wherein said composition has a pH in the range of 3.5 to 8.  
     
     
         10 . The composition of  claim 9 , wherein said composition after aerosolisation essentially has a comparable droplet size as to a composition consisting of only nucleic acid at equal concentrations of nucleic acid.  
     
     
         11 . A method of preparing the composition of  claim 1 , comprising the steps of: 
 (a) exposing said cationic chitosan oligomer to an aqueous solvent;    (b) mixing the aqueous solution of step (a) with said nucleic acid in an aqueous solvent; and    (c) reducing the volume of the product solution obtained in step (b) to achieve a desired concentration of the said composition.    
     
     
         12 . A method of administering nucleic acid to a mammal, using the composition of  claim 1 , and introducing the composition into the mammal.  
     
     
         13 . The method of  claim 12 , wherein the composition is introduced into the mammal by administration to mucosal tissues by pulmonary, nasal, oral, buccal, sublingual, rectal or vaginal routes.  
     
     
         14 . The method of  claim 12 , wherein the composition is introduced into the mammal by administration to submucosal tissues by parenteral routes that is intravenous, intramuscular, intradermal, subcutaneous or intracardiac administration, or to internal organs, blood vessels or other body surfaces or cavities exposed during surgery.  
     
     
         15 . A method of  claim 12  comprising the composition of  claim 1 , whereby said nucleic acid is capable of expressing its function inside said cell.  
     
     
         16 . The use of the composition of  claim 1 , in the manufacture of a medicament for prophylactic or therapeutic treatment of a mammal, or in the manufacture of a diagnostic agent for use in in vivo or in vitro diagnostic methods.  
     
     
         17 . The use of the composition of  claim 16  in the manufacture of a medicament for use in gene therapy, antisense theraphy, or genetic vaccination for prophylactic or therapeutic treatment of malignancies, autoimmune diseases, inherited disorders, pathogenic infections and other pathological diseases.