Compositions and methods for modified dendrimer nanoparticle delivery

A method for delivering a therapeutic, prophylactic and/or diagnostic agent to a subject, comprising administering to the subject a modified dendrimer nanoparticle comprising

• (i) one or more dendrimers selected from the group consisting of one to seven generation poly(ethylene imine) dendrimers and two to seven generation poly(propylene imine) dendrimers;
• (ii) one or more amphiphilic polymers, wherein the amphiphilic polymer is 1,2-dimystistoyl-sn-glycerol-3-phosphoethanolamine-N-[methoxy (polyethylene glycol)-2000]
• wherein the amphiphilic polymer is not a dendrimer;
• and
• (iii) one or more nucleic acids that express or encode one or more therapeutic, prophylactic and/or diagnostic agents;
• wherein the nucleic acids are encapsulated in the dendrimer nanoparticle wherein the nanoparticle does not include cholesterol.