Encapsulation of plasmid DNA (lipogenes™) and therapeutic agents with nuclear localization signal/fusogenic peptide conjugates into targeted liposome complexes
A method is disclosed for encapsulating plasmids, oligonucleotides or negatively-charged drugs into liposomes having a different lipid composition between their inner and outer membrane bilayers and able to reach primary tumors and their metastases after intravenous injection to animals and humans. The formulation method includes complex formation between DNA with cationic lipid molecules and fusogenic/NLS peptide conjugates composed of a hydrophobic chain of about 10-20 amino acids and also containing four or more histidine residues or NLS at their one end. The encapsulated molecules display therapeutic efficacy in eradicating a variety of solid human tumors including but not limited to breast carcinoma and prostate carcinoma. Combination of the plasmids, oligonucleotides or negatively-charged drugs with other anti-neoplastic drugs (the positively-charged cis-platin, doxorubicin) encapsulated into liposomes are of therapeutic value. Also of therapeutic value in cancer eradication are combinations of encapsulated the plasmids, oligonucleotides or negatively-charged drugs with HSV-tk plus encapsulated ganciclovir.
1. A method for producing micelles with negatively charged entrapped therapeutic agents, comprising:
a) combining an effective amount of a negatively charged therapeutic agent with a buffer solution containing about 20% to about 80% ethanol and an effective amount of a cationic lipid in a ratio where about 30% to about 90% the negatively charged atoms on the therapeutic agents are neutralized by positive charges on the cationic lipids to form an electrostatic micelle complex; and
b) combining the electrostatic micelle complex of step a) with an effective amount of a fusogenic-karyophilic peptide conjugate in a ratio wherein the negatively charged therapeutic agents are almost completely neutralized by a majority of the cationic lipids and fusogenic-karyophilic peptide conjugates, thereby producing micelles with entrapped therapeutic agents.
2. The method of claim 1 , further comprising combining an effective amount of an anionic lipid in step b) when the total of the positive charges contributed by the cationic lipids exceed the total of negative charges contributed by the therapeutic agents.
3. The method of claim 1 , further comprising combining an effective amount of a DNA condensing agent selected from the group consisting of spermine, spermidine, polylysine, polyarginine, polyhistidine, polyornithine and magnesium or a divalent metal ion.
4. A method for producing liposome encapsulated micelles with negatively charged polynucleotides, comprising:
a) combining an effective amount of a negatively charged polynucleotide with a buffer solution containing about 20% to about 80% ethanol and an effective amount of a cationic lipid in a ratio where about 30% to about 90% the negatively charged atoms on the negatively charged polynucleotides are neutralized by positive charges on the cationic lipids to form an electrostatic micelle complex; and
b) combining the electrostatic micelle complex of step a) with an effective amount of a fusogenic-karyophilic peptide conjugate and an effective amount of an encapsulating lipid solution in a ratio wherein the negatively charged polynucleotides are almost completely neutralized by a majority of the cationic lipids and fusogenic-karyophilic peptide conjugates and liposomes, thereby producing said liposome encapsulated micelles.
5. The method of claim 4 , wherein the encapsulating lipid solution comprises a liposome.
6. The method of claim 5 , wherein the liposome comprises vesicle-forming lipids and between about 1 to about 7 mole percent of distearoylphosphatidyl ethanolamine (DSPE) derivatized with an effective amount of polyethyleneglycol.
7. The method of claim 4 , wherein at least one lipid in step a or step b is chosen from the group consisting of: cholesterol, phosphatidycholine (PC), phosphatidyethanolamine (PE), phosphatidylinositol (PI), sphingomyelin (SM), dioleoylphosphatidylethanolamine (DOPE), hydrogenated soy phosphatidylcholine (HSPC), lecithin, phosphatidylethanolamine, lysolecithin, lysophosphatidylethanolamine phosphatidylserine, phosphatidylinositol, sphingomyelin, cephalin, cardiolipin, phosphatidic acid, cerebrosides, distearoylphosphatidylethanolamine (DSPE), dioleoylphophatidycholine (DOPC), dipalmitoylphosphatidylcholine (DPPC), palmitoyloleoylphosphatidylcholine (POPC), palmitoyloleoylphophatidylethanolamine (POPE), dioleoylphophatidylethanolamine-4-(N-maleimido-methyl) cyclohexane-1-carboxylate (DOPE-mal), stearylamine, dodecylamine, hexadecylamine, isopropyl myristate, triethanolamine-lauryl sulfate, alkyl-aryl sulfate, acetyl palmitate, glycerol ricinoleate, hexadecyl stereate, amphoteric acrylic polymers, polyethyloxylated fatty acid amides, dipalmitoylphosphatidylglycerol (DPPG), dioleoylphosphatidylglycerol and (DOPG), and PEG-DSPE.
8. A micelle with an entrapped therapeutic agent produced by the method comprising
a) combining an effective amount of a negatively charged therapeutic agent with a buffer solution containing about 20% to about 80% ethanol and an effective amount of a cationic lipid in a ratio where about 30% to about 90% the negatively charged atoms on the therapeutic agents are neutralized by positive charges on the cationic lipids to form an electrostatic micelle complex; and
b) combining the electrostatic micelle complex of step a) with an effective amount of a fusogenic-karyophilic peptide conjugate in a ratio wherein the negatively charged therapeutic agents are almost completely neutralized by a majority of the cationic lipids and fusogenic-karyophilic peptide conjugates, thereby producing micelles with entrapped therapeutic agents.
9. The micelle of claim 8 , wherein the method further comprises combining an effective amount of an anionic lipid in step b) when the total of the positive charges contributed by the cationic lipids exceed the total of negative charges contributed by the therapeutic agents.
10. The micelle of claim 9 , wherein the method further comprises combining an effective amount of a DNA condensing agent selected from the group consisting of spermine, spermidine, polylysine, polyarginine, polyhistidine, polyornithine and magnesium or a divalent metal ion.
11. A liposome encapsulated therapeutic agent produced by a method comprising:
a) combining an effective amount of a negatively charged therapeutic agent with a buffer solution containing about 20% to about 80% ethanol and an effective amount of a cationic lipid in a ratio where about 30% to about 90% the negatively charged atoms on the therapeutic agents are neutralized by positive charges on the cationic lipids to form an electrostatic micelle complex; and
b) combining the electrostatic micelle complex of step a) with an effective amount of a fusogenic-karyophilic peptide conjugate and an effective amount of an encapsulating lipid solution in a ratio wherein the negatively charged therapeutic agents are almost completely neutralized by a majority of the cationic lipids and fusogenic-karyophilic peptide conjugates and liposomes, thereby producing said liposome encapsulated micelles.