There are many short-acting drugs available to treat hypertension. However, most patients fail to adhere to a daily, multi-drug antihypertensive regimen with frequent side effects. Thus, normal blood pressure is restored in only a minority of hypertensive patients, and only long-term, targeted antihypertensive therapies with fewer side effects will fundamentally impact the epidemic levels of hypertension in the Western world. The studies in this proposal seek to develop a novel, long-term therapy for hypertension by using an adeno-associated viral (AAV) vector containing an enhanced smooth muscle specific promoter (EnSM221) to deliver exogenous microRNA directed against vascular L-type (CaV1.2) calcium channels. Notably, CaV1.2 channels already are the target of clinical calcium channel blocking drugs used to lower blood pressure. However, our strategy will use AAV-mediated delivery of CaV1.2 channel microRNA to enable long- term and vascular-specific knockdown of calcium channel expression.
Our aims i nclude: 1) to demonstrate the ability of CaV1.2 channel microRNA to reduce blood pressure for at least 8 weeks without serious side effects in hypertensive mice, 2) confirm in vivo and in vitro that the vasoconstrictor function of CaV1.2 channels is suppressed in small mesenteric arteries, and 3) demonstrate that decreases in vascular CaV1.2 channel expression, whole-cell Ca2+ current, and restoration of K+ channel expression and resting membrane potential in mesenteric arterial cells correlate with the antihypertensive effect of CaV1.2 channel microRNA delivered by AAV to the vasculature. The results of this study will help to establish a foundation for using targeted AAV and microRNA technology to treat systemic hypertension and other chronic vascular abnormalities that are poorly controlled by short-term therapies.
High blood pressure known as hypertension afflicts over 60 million Americans and can lead to even more debilitating conditions. While there are numerous short-acting medications (including calcium channel blockers) to treat hypertension, most patients do not take their medications faithfully and consequently less than one third of patients have their blood pressure adequately controlled. We have developed a small RNA-based therapeutic (microRNA) which decreases expression of a calcium channel found in blood vessels that is also the site of action of all antihypertensive calcium channel blockers. When incorporated into a safe adeno associated virus, our therapeutic can continuously produce more microRNA over a period of months. In addition our therapeutic is coupled to a DNA sequence that will selectively generate the desired microRNA only in vascular smooth muscle cells that make up the wall of blood vessels. This is likely to reduce side effects encountered with many orally administered antihypertensive medications, which spread throughout the body. A longer lasting therapy with fewer side effects may be extremely beneficial for the >40 million Americans whose hypertension is not properly managed.