Intravenous angiotensinogen antisense in AAV-based vector decreases hypertension

Angiotensinogen (AGT) has been linked to hypertension. Because there are no direct inhibitors of AGT, we have developed antisense (AS) inhibition of A GT mRNA delivered in an adeno-associated virus (AAV)-based plasmid vector. This plasmid, driven by the cytomegalovirus promoter, contains a green fluo rescent protein reporter gene and AS cDNA for rat AGT. Transfection of the plasmid into rat hepatoma cells brought a strong expression of the transgen es and a significant reduction in the level of AGT. In the in vivo study, n aked plasmid DNA was intravenously injected into adult spontaneously hypert ensive rats at different doses (0.6, 1.5, and 3 mg/kg). Expression of AGT A S mRNA was present in liver and heart, and it lasted longer in the liver. A ll three doses produced a significant decrease in blood pressure (BP). BP d ecreased for 2, 4, and 6 days, respectively. The lowest dose decreased BP b y 12 +/- 3.0 mmHg, whereas the higher doses decreased BP by up to 22.5 +/- 5.2 mmHg compared with the control rats injected with saline (P < 0.01). Th e injection of the plasmid with liposomes produced a more profound and long er reduction (8 days) in BP. Consistent changes in plasma AGT level were ob served. Sense plasmid had no effect. No liver toxicity was observed after i njection of AS plasmid with or without liposomes. Our results suggest that the systemic delivery of AS against AGT mRNA by AAV-based plasmid vector, e specially with liposomes, may have potential for gene therapy of hypertensi on and that further studies with the plasmid packaged into a recombinant AA V vector for a longer-lasting AS effect are warranted.