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J Control Release ; 157(2): 224-34, 2012 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-21945680

RESUMO

Microbubble ultrasound contrast agents are being developed as image-guided gene carriers for targeted delivery in vivo. In this study, novel polyplex-microbubbles were synthesized, characterized and evaluated for systemic circulation and tumor transfection. Branched polyethylenimine (PEI; 25 kDa) was modified with polyethylene glycol (PEG; 5 kDa), thiolated and covalently attached to maleimide groups on lipid-coated microbubbles. The PEI-microbubbles demonstrated increasingly positive surface charge and DNA loading capacity with increasing maleimide content. The in vivo ultrasound contrast persistence of PEI-microbubbles was measured in the healthy mouse kidney, and a two-compartment pharmacokinetic model accounting for free and adherent microbubbles was developed to describe the anomalous time-intensity curves. The model suggested that PEI loading dramatically reduced free circulation and increased nonspecific adhesion to the vasculature. However, DNA loading to form polyplex-microbubbles increased circulation in the bloodstream and decreased nonspecific adhesion. PEI-microbubbles coupled to a luciferase bioluminescence reporter plasmid DNA were shown to transfect tumors implanted in the mouse kidney. Site-specific delivery was achieved using ultrasound applied over the tumor area following bolus injection of the DNA/PEI-microbubbles. In vivo imaging showed over 10-fold higher bioluminescence from the tumor region compared to untreated tissue. Ex vivo analysis of excised tumors showed greater than 40-fold higher expression in tumor tissue than non-sonicated control (heart) tissue. These results suggest that the polyplex-microbubble platform offers improved control of DNA loading and packaging suitable for ultrasound-guided tissue transfection.


Assuntos
Meios de Contraste/farmacocinética , Técnicas de Transferência de Genes , Maleimidas/farmacocinética , Microbolhas , Neoplasias/diagnóstico por imagem , Polietilenoimina/farmacocinética , Animais , Linhagem Celular Tumoral , Meios de Contraste/química , DNA/administração & dosagem , DNA/farmacocinética , Feminino , Humanos , Rim/diagnóstico por imagem , Rim/metabolismo , Maleimidas/química , Camundongos , Camundongos Nus , Neoplasias/metabolismo , Plasmídeos , Polietilenoglicóis/química , Polietilenoimina/química , Ultrassonografia
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