(1261) Safe Delivery of a Nanoparticle-Based Therapy to the Pulmonary Endothelium in a Rodent Model

We have previously shown that Polyethylenimine-(5) myristic acid/ poly(ethylene glycol)-oleic acid/cholesterol (PEI-PEG) nanoparticles target pulmonary endothelium in adult mice and in culture. We sought to determine if PEI-PEG nanoparticles could be used to deliver a targeted therapy in utero without disruption of normal lung development. Such a therapy could provide a breakthrough for in utero therapies for congenital pulmonary disorders as well as single gene disorders of the lungs.

Study Design:
Dylight 647-labeled plasmids were covalently linked to PEI-PEG nanoparticles. These nanoparticles were subsequently injected (25 uL per fetus, total of 6 fetuses) intraperitoneally into the fetuses of wild type pregnant rodents at gestational age E17.5, with un-injected fetuses as controls. At E20.5, fetuses were imaged via In Vivo Imaging System (IVIS) for signs of the fluorescent nanoparticles, and lung tissues were harvested for examination via flow cytometry and immunofluorescent staining. Pathologic evaluation and grading were performed.

Results:

IVIS revealed that intrafetal intraperitoneal injections resulted in nanoparticle localization to the fetal lungs with a >10 million-fold increase in epifluorescence over background in treated fetuses (p< 0.001). Immunofluorescent staining confirmed significant uptake of the nanoparticles in the fetal lung tissue (Figure 1B) without any disruption of normal fetal lung development seen on histological evaluation (Figure 1C). Flow cytometry confirmed the results, with 52% of pulmonary endothelial cells of injected fetuses having 647 fluorescence (5 injected fetuses, range 43.5%-62.1% vs 6 controls, range 0.0-0.2%, p < 0.001) vs 0% of controls.

Conclusion:

PEI-PEG successfully delivers fluorescent plasmids into the fetal lungs without disruption of normal fetal lung development and is a promising platform for treating pulmonary disorders in-utero.