Selective Targeting of Alveolar Capillaries in Neonatal Lung Injury - PROJECT SUMMARY. Endothelial cell (EC) dysfunction occurs in a variety of acute and chronic pulmonary diseases. To correct EC dysfunction, there is an unmet need for development of nanoparticle systems that can deliver drugs and nucleic acids into pulmonary ECs in vivo with high efficiency and precision. While several nanoparticle delivery systems targeting ECs have been recently developed, none of these systems are specific to lung ECs without targeting ECs in other organs of the body. Bronchopulmonary dysplasia (BPD) is a severe complication of prematurity in newborns and infants, especially those born prior to 28 weeks of gestation. BPD is associated with significant mortality and morbidity, and it causes an increased susceptibility to chronic pulmonary diseases later in life. The most severe BPD cases (BPD-PH) are accompanied by irreversible vascular remodeling and pulmonary hypertension (PH) after exposure of preterm infants to supplemental oxygen. There is an urgent need for innovative therapeutic approaches to prevent vascular remodeling and stimulate endothelial regeneration in BPD-PH infants. FOXM1 is a well-known pro-proliferative transcription factor which is required for EC proliferation during lung regeneration after injury that is caused by various insults. We propose to test the hypothesis that newly developed and lung capillary endothelial-specific nanoparticles complexed with the FOXM1 minicircle DNA plasmid will stimulate lung regeneration and decrease PH in mouse and rat BPD-PH models. In Aim 1, we created a novel class of hybrid polyplex nanoparticles (P22-F1 PBAE/PEI/PEG) and demonstrated that after systemic (intravenous) injection these nanoparticles are non-toxic and effectively deliver non-integrating DNA plasmids to capillary ECs in the lung-specific manner. We propose to determine molecular mechanisms through which the P22-F1 PBAE/PEI/PEG nanoparticles specifically target lung capillary ECs without targeting other cells and organs in the body. Specifically, we will examine the cell surface binding of the nanoparticles, their endocytosis, endosomal/lysosomal escaping, and the cargo release, all of which are important mechanisms for successful delivery of DNA plasmids to develop nanoparticle therapeutics. In Aim 2, we will determine whether the P22-F1 PBAE/PEI/PEG nanoparticle delivery of the FOXM1 minicircle DNA vector into pulmonary capillaries will stimulate EC regeneration, prevent PH, and improve lung function in mouse and rat BPD-PH models. Conditional knockout mice will be used to perform the inactivation of Foxm1-floxed alleles in general capillary cells (gCAPs) or aerocytes (aCAPs) to determine differential requirements for FOXM1 in gCAPs and aCAPs during lung regeneration in a mouse BPD-PH model. We will also use mouse and human BPD-PH lung tissues to perform omics studies and identify novel downstream targets of FOXM1 in regenerating gCAPs and aCAPs. Altogether, the proposed preclinical studies will directly test whether lung capillary endothelial-specific delivery of the FOXM1 minicircle vector has therapeutic potential in BPD-PH.
