Encapsulation of Bioactive Complexes in Liposomes

Abstract

This invention provides a method to prepare liposome-encapsulated bioactive agents, such as nucleic acids, comprising complexation of the bioactive agents to reverse micelles prior to forming liposomes, as well as methods of using the liposomes so formed and formulations to deliver nucleic acids to cells.

1 . A method of encapsulating a bioactive complex in a liposome which comprises the steps of:
 (a) dissolving at least one amphipathic lipid in one or more organic solvents   (b) combining a first aqueous suspension comprising a bioactive agent with the lipid containing organic solution of step (a) so as to form an emulsion comprising the bioactive agent and the lipid;   (c) adding a second aqueous suspension comprising a complexing agent to the emulsion of step (b),   (d) incubate the emulsion of step (c) to allow the complexing agent to contact the bioactive agent thereby forming a complex of the bioactive agent with the complexing agent within the lipid stabilized water droplets; wherein said complex is no greater in diameter than the diameter of the droplet and,   (e) removing the organic solvent from the suspension of step (d), so as to form liposomes comprising the complexed bioactive agent and the lipid.   
   
   
       2 . A method of encapsulating a bioactive complex in a liposome which comprises the steps of:
 (a) dissolving at least one amphipathic lipid in one or more organic-solvents   (b) combining a first aqueous suspension comprising a complexing agent with the lipid containing organic solution of step (a) so as to form an emulsion comprising the complexing agent and the lipid;   (c) adding a second aqueous suspension comprising a bioactive agent to the emulsion of step (b),   (d) incubate the emulsion of step (c) to allow the complexing agent to contact the bioactive agent thereby forming a complex of the bioactive agent with the complexing agent within the lipid stabilized water droplets; wherein said complex is no greater in diameter than the diameter of the droplet and,   (e) removing the organic solvent from the suspension of step (d), so as to form liposomes comprising the complexed bioactive agent and the lipid.   
   
   
       3 . The method of  claim 1 , wherein the bioactive agent is a nucleic acid 
   
   
       4 . The method of  claim 1 , wherein the nucleic acid is DNA.