Delivery of Human ACE2 Across the Blood Brain Barrier Attenuated Development of Neurogenic Hypertension Using An Engineered Liposome-Based Delivery System

Abstract

<b>Abstract ID 18644</b> <b>Poster Board 502</b> The blood brain barrier (BBB) blocks therapeutic drugs access to the brain cardiovascular regulatory regions in the treatment of hypertension, which could lead to drug-resistant hypertension. To overcome this challenge, PEGylated liposomes were surface-modified with transferrin (Tf) for specific binding Tf receptor on the BBB and conjugated to a cell-penetrating peptide (CPP) to enhance their cellular uptake into the brain. Here, we evaluated the efficacy of Tf-CPP-liposome to deliver angiotensin-converting enzyme 2 (ACE2) gene or EGFP (control) gene across the BBB in Sprague Dawley (SD) rats. Systemic administration of the Tf-CPP-Liposomes carrying a lentiviral vector plasmid encoding EGFP (control) or ACE2 (150 μg/kg, I.V.) significantly increased EGFP or ACE2 expression respectively in the paraventricular nucleus (PVN) brain area and in the liver, detected using Western Blots and Real-time PCR. However, without Tf, CPP-Liposome-mediated expression of EGFP was significantly lower than Tf-CPP-Liposome in the brain. EGFP expressions in the liver are comparable between two liposomes, suggesting modification with Tf increased the specific delivery to the brain. The immunohistochemistry study demonstrated that the EGFP expression in the brain was localized on the neurons within the PVN by staining using antibodies against neuronal marker, NeuN and glial cell marker, GFAP, in the rats which received intravenous administration of Tf-CPP-Liposome EGFP. Next, we examine the effect of Tf-CPP-Liposome-mediated overexpression of ACE2 in the brain on development of hypertension. Angiotensin II (Ang II, 100ng/min) were consistently infused into left lateral ventricule (ICV) using osmotic pumps in SD rats. ICV infusion of Ang II significantly elevated mean arterial pressure (MAP, from 93.2±4.0 mmHg to 168.4±4.4 mmHg, n=5, P&lt;0.05), reaching to the peak in 7 days (169.2±11.2 mmHg) and keeping consistent at high level for at least 3 weeks. In addition, Ang II-induced elevation in blood pressure was associated with cardiac hypertrophy and fibrosis. More interestingly, treatment with Tf-CPP-Liposome-ACE2 (150 μg/kg, I.V.) significantly attenuated Ang II-induced increases in MAP by 30%. However, Tf-CPP-Liposome-EGFP did not alter Ang II-induced pressor effect on MAP. Tf-CPP-Liposome-ACE2 also did not change the blood pressure in sham rats, which received ICV perfusion of PBS. Moreover, intravenous administration of Tf-CPP-Liposome-ACE2 significantly attenuated Ang II-induced cardiac hypertrophy and fibrosis. In summary, Tf-CPP-Liposome successfully delivered ACE2 gene across the BBB; and elevated ACE2 expression in brain cardiovascular regulatory areas. This Tf-CPP-Liposome-mediated overexpression of ACE2 dramatically attenuated neurogenetic hypertension by systemic administration. Support/Funding Information: NIH HL143519 and NIH HL124338.