391. Targeted Delivery of Adenovirus Expressing eNOS to the Endothelium In Vivo Lowers Blood Pressure in Hypertensive Rats

Abstract

Top of pageAbstract Background: Vascular dysfunction associated with oxidative stress is a key feature of human essential hypertension. The stroke prone spontaneously hypertensive rat (SHRSP) is a model of this condition. We have shown that local in vivo application of adenovirus encoding for either endothelial nitric oxide synthase (eNOS) or extracellular superoxide dismutase (SOD3) improves impaired nitric oxide (NO) bioavailability and endothelial function in the carotid artery of the SHRSP (1,2). The present study sought to determine the effects of systemic administration of these vectors on blood pressure in the SHRSP. Since adenovirus is sequestered and degraded by the liver we also evaluated specific targeting of vectors to the vascular endothelium, using a bispecific antibody 3. Methods: Systolic blood pressure (SBP) was recorded by radiotelemetry in 10 to 11 week-old male SHRSP for a total of 8 weeks. Four hours after infusion of 3×1011 particles of null adenovirus (to saturate hepatic Kupffer cells), rats received a single infusion of 1×1010 particles of recombinant adenoviral vectors ('RAd'), or vehicle, encoding for eNOS, SOD3 or EGFP via the femoral vein (n = 5 per group). Two further groups (n = 5) received RAdeNOS or RAdEGFP pre-incubated with a bispecific antibody (Fab9B9) which binds to both the adenoviral coat and angiotensin converting enzyme. Telemetry data was analysed using a Linear Mixed Effects Model. Results: Biodistribution studies using Lightcycler real-time PCR revealed that the vast majority of non-targeted adenoviral particles accumulated in liver, with lower levels in spleen, lung, aorta and carotid artery. Transgene expression, determined by immunohistochemistry, paralleled this pattern. Non-targeted over-expression of extracellular SOD or eNOS had no effect on SBP. However, endothelial targeting increased vector accumulation in the lung, and pulmonary eNOS immunoreactivity was increased in rats which had received Fab9B9-RAdeNOS but not Fab9B9-RAdEGFP. Functional studies found that these changes were accompanied by a significant increase in basal NO bioavailability in small pulmonary arteries. Moreover, in contrast to non-targeted vectors, Fab9B9-RAdeNOS caused a significant and sustained reduction in SBP relative to the Fab9B9-RAdEGFP control (see Figure 1). Conclusion: This study shows for the first time that specific vascular targeting of adenoviral-mediated gene delivery can modify systemic cardiovascular phenotype.