Lipid membrane structure for delivery into sirna cell

Abstract

A lipid membrane structure includes, as lipid components, a lipid compound represented by Formula (I):[in the formula, a represents an integer of 3 to 5; b represents an integer of 0 or 1; R1 and R2 each independently represents a linear hydrocarbon group that may have —CO—O—; and X represents a 5- to 7-membered non-aromatic heterocyclic group or a group represented by Formula (B) (in the formula, d represents an integer of 0 to 3, and R3 and R4 each independently represents a C1-4 alkyl group or a C2-4 alkenyl group, where, R3 and R4 may be bonded to each other to form a 5- to 7-membered non-aromatic heterocycle (where, one or two C1-4 alkyl groups or C2-4 alkenyl groups may be substituted on the ring)].

1 . A method of delivery of nucleic acid, comprising
 administering to a subject a lipid membrane structure comprising a nucleic acid, the nucleic acid being sealed in the lipid membrane structure, wherein   the lipid membrane structure comprises one or more pH-sensitive cationic lipids, one or more cholesterol-based lipids and one or more PEG-modified lipids,   the lipid membrane structure has a pKa of 4.5 to 8.2,   an average particle diameter of the lipid membrane structure is 60 to 140 nm, or 20 to 50 nm, and   the administering of the lipid membrane structure results in an expression of the protein encoded by the nucleic acid in liver.   
     
     
         2 . The method of delivery of nucleic acid according to  claim 1 , wherein a total content of the pH-sensitive cationic lipids is 60 to 70 mol%. 
     
     
         3 . The method of delivery of nucleic acid according to  claim 2 , wherein the pH-sensitive cationic lipid has a tertiary amino group at an end thereof. 
     
     
         4 . The method of delivery of nucleic acid according to  claim 3 , wherein the pH-sensitive cationic lipid has a 5- to 7-membered non-aromatic heterocyclic group at an end thereof. 
     
     
         5 . The method of delivery of nucleic acid according to  claim 4 , wherein the pH-sensitive cationic lipid has a structure in which an alkylene group having 0 to 3 carbon atoms is bonded to an ester group, and a 5- to 7-membered non-aromatic heterocyclic group is bonded thereto. 
     
     
         6 . The method of delivery of nucleic acid according to  claim 5 , wherein the pH-sensitive cationic lipid has a hydrophilic site and two hydrophobic scaffolds, and the hydrophilic site has a structure in which an alkylene group having 0 to 3 carbon atoms is bonded to an ester group, and a 5- to 7-membered non-aromatic heterocyclic group is bonded thereto. 
     
     
         7 . The method of delivery of nucleic acid according to  claim 6 , wherein the two hydrophobic scaffolds each independently have
 a structure in which an alkylene group having 4 to 12 carbon atoms and a saturated or unsaturated aliphatic group having 4 to 25 carbon atoms and having 0 to 2 unsaturated bonds are bonded, or   a structure in which an alkylene group having 4 to 12 carbon atoms and a saturated or unsaturated fatty acid ester group having 5 to 26 carbon atoms and having 0 to 2 unsaturated bonds are bonded.   
     
     
         8 . The method of delivery of nucleic acid according to  claim 7 , wherein the pH-sensitive cationic lipid is a lipid compound represented by Formula (I) or a salt thereof, 
       
         
           
           
               
               
           
         
       
        wherein in the formula, a represents an integer of 3 to 5; b represents an integer of 0 or 1; and R 1  and R 2  each independently represents a group represented by Formula (A): 
       
         
           
           
               
               
           
         
       
        wherein in the formula, q represents an integer of 1 to 9; r represents 0 or 1; s represents an integer of 1 to 3; t represents 0 or 1; u represents an integer of 1 to 8; c represents 0 or 1; and v represents an integer of 4 to 12, where, a case in which q is an integer of 3 to 5, r and t are 1, s is 1, and u + v is an integer of 6 to 10 is excluded in a case where both b and c are 0; and X represents a group represented by Formula (B): 
       
         
           
           
               
               
           
         
       
        wherein in the formula, d represents an integer of 0 to 3, and R 3  and R 4  each independently represents a C 1-4  alkyl group or a C 2-4  alkenyl group, where the C 1-4  alkyl group or C 2-4  alkenyl group may be substituted by one or two phenyl groups, and R 3  and R 4  are bonded to each other to form a 5- to 7-membered non-aromatic heterocycle, where one or two C 1-4  alkyl groups or C 2-4  alkenyl groups may be substituted on the heterocycle ring. 
     
     
         9 . The method of delivery of nucleic acid according to  claim 1 , wherein the lipid membrane structure has a pKa of 5.85 to 6.95. 
     
     
         10 . A lipid membrane structure comprising a nucleic acid and a lipid component, wherein 
 the lipid component comprises one or more pH-sensitive cationic lipids, one or more cholesterol-based lipids and one or more PEG-modified lipids, and   the nucleic acid is sealed in the lipid component,   the lipid membrane structure has a pKa of 4.5 to 8.2,   an average particle diameter of the lipid membrane structure is 60 to 140 nm, and   the administering of the lipid membrane structure results in an expression of the protein encoded by the nucleic acid in liver.   
     
     
         11 . The lipid membrane structure according to  claim 10 , wherein a total content of the pH-sensitive cationic lipids is 60 to 70 mol%. 
     
     
         12 . The lipid membrane structure according to  claim 11 , wherein the pH-sensitive cationic lipid has a tertiary amino group at an end thereof. 
     
     
         13 . The lipid membrane structure according to  claim 12 , wherein the pH-sensitive cationic lipid has a 5- to 7-membered non-aromatic heterocyclic group at an end thereof. 
     
     
         14 . The lipid membrane structure according to  claim 13 , wherein the pH-sensitive cationic lipid has a structure in which an alkylene group having 0 to 3 carbon atoms is bonded to an ester group, and a 5- to 7-membered non-aromatic heterocyclic group is bonded thereto. 
     
     
         15 . The lipid membrane structure according to  claim 14 , wherein the pH-sensitive cationic lipid has a hydrophilic site and two hydrophobic scaffolds, and the hydrophilic site has a structure in which an alkylene group having 0 to 3 carbon atoms is bonded to an ester group, and a 5- to 7-membered non-aromatic heterocyclic group is bonded thereto. 
     
     
         16 . The lipid membrane structure according to  claim 15 , wherein the two hydrophobic scaffolds each independently have
 a structure in which an alkylene group having 4 to 12 carbon atoms and a saturated or unsaturated aliphatic group having 4 to 25 carbon atoms and having 0 to 2 unsaturated bonds are bonded, or   a structure in which an alkylene group having 4 to 12 carbon atoms and a saturated or unsaturated fatty acid ester group having 5 to 26 carbon atoms and having 0 to 2 unsaturated bonds are bonded.   
     
     
         17 . The lipid membrane structure according to  claim 16 , wherein the pH-sensitive cationic lipid is a lipid compound represented by Formula (I) or a salt thereof, 
       
         
           
           
               
               
           
         
       
        wherein in the formula, a represents an integer of 3 to 5; b represents an integer of 0 or 1; and R 1  and R 2  each independently represents a group represented by Formula (A): 
       
         
           
           
               
               
           
         
       
        wherein in the formula, q represents an integer of 1 to 9; r represents 0 or 1; s represents an integer of 1 to 3; t represents 0 or 1; u represents an integer of 1 to 8; c represents 0 or 1; and v represents an integer of 4 to 12, where, a case in which q is an integer of 3 to 5, r and t are 1, s is 1, and u + v is an integer of 6 to 10 is excluded in a case where both b and c are 0; and X represents a group represented by Formula (B): 
       
         
           
           
               
               
           
         
       
        wherein in the formula, d represents an integer of 0 to 3, and R 3  and R 4  each independently represents a C 1-4  alkyl group or a C 2-4  alkenyl group, where the C 1-4  alkyl group or C 2-4  alkenyl group may be substituted by one or two phenyl groups, and R 3  and R 4  are bonded to each other to form a 5- to 7-membered non-aromatic heterocycle, where one or two C 1-4  alkyl groups or C 2-4  alkenyl groups may be substituted on the heterocycle ring. 
     
     
         18 . The lipid membrane structure according to  claim 10 , wherein the lipid membrane structure has a pKa of 5.85 to 6.95. 
     
     
         19 . A lipid membrane structure comprising a nucleic acid and a lipid component, wherein 
 the lipid component comprises one or more pH-sensitive cationic lipids, one or more cholesterol-based lipids and one or more PEG-modified lipids, and   the nucleic acid is sealed in the lipid component,   the lipid membrane structure has a pKa of 4.5 to 8.2,   an average particle diameter of the lipid membrane structure is 20 to 50 nm, and   the administering of the lipid membrane structure results in an expression of the protein encoded by the nucleic acid in liver.