Thinking globally, acting locally. The promise of cardiovascular gene therapy

Baroreceptor and chemoreceptor contributions to the hypertensive response to bilateral carotid occlusion in conscious mice

This study aimed to characterize the role played by baroreceptors and chemoreceptors in the hypertensive response to bilateral carotid occlusion (BCO) in conscious C57BL mice. On the day before the experiments the animals were implanted with pneumatic cuffs around their common carotid arteries and a femoral catheter for measurement of arterial pressure. Under the same surgical approach, groups of mice were submitted to aortic or carotid sinus denervation or sham surgery. BCO was performed for 30 or 60 s, promoting prompt and sustained increase in mean arterial pressure and fall in heart rate. Compared with intact mice, the hypertensive response to 30 s of BCO was enhanced in aortic-denervated mice (52 ± 4 vs. 41 ± 4 mmHg; P < 0.05) but attenuated in carotid sinus-denervated mice (15 ± 3 vs. 41 ± 4 mmHg; P < 0.05). Suppression of peripheral chemoreceptor activity by hyperoxia [arterial partial pressure of oxygen (Pa(O(2))) > 500 mmHg] attenuated the hypertensive response to BCO in intact mice (30 ± 6 vs. 51 ± 5 mmHg in normoxia; P < 0.05) and abolished the bradycardia. It did not affect the hypertensive response in carotid sinus-denervated mice (20 ± 4 vs. 18 ± 3 mmHg in normoxia; P < 0.05). The attenuation of the hypertensive response to BCO by carotid sinus denervation or hyperoxia indicates that the hypertensive response in conscious mice is mediated by both baro- and chemoreceptors. In addition, aortic denervation potentiates the hypertensive response elicited by BCO in conscious mice.

Cardiovascular gene delivery: The good road is awaiting

Atherosclerotic cardiovascular disease is a leading cause of death worldwide. Despite recent improvements in medical, operative, and endovascular treatments, the number of interventions performed annually continues to increase. Unfortunately, the durability of these interventions is limited acutely by thrombotic complications and later by myointimal hyperplasia followed by progression of atherosclerotic disease over time. Despite improving medical management of patients with atherosclerotic disease, these complications appear to be persisting. Cardiovascular gene therapy has the potential to make significant clinical inroads to limit these complications. This article will review the technical aspects of cardiovascular gene therapy; its application for promoting a functional endothelium, smooth muscle cell growth inhibition, therapeutic angiogenesis, tissue engineered vascular conduits, and discuss the current status of various applicable clinical trials.

Genetic targeting for cardiovascular therapeutics: are we near the summit or just beginning the climb?

This article is based on an Experimental Biology symposium held in April 2001 and presents the current status of gene therapy for cardiovascular diseases in experimental studies and clinical trials. Evidence for the use of gene therapy to limit neointimal hyperplasia and confer myocardial protection was presented, and it was found that augmenting local nitric oxide (NO) production using gene transfer (GT) of NO synthase or interruption of cell cycle progression through a genetic transfer of cell cycle regulatory genes limited vascular smooth muscle hyperplasia in animal models and infra-inguinal bypass patients. The results of application of vascular endothelial growth factor (VEGF) GT strategies for therapeutic angiogenesis in critical limb and myocardial ischemia in pilot clinical trials was reviewed. In addition, experimental evidence was presented that genetic manipulation of peptide systems (i.e., the renin-angiotensin II system and the kallikrein-kinin system) was effective in the treatment of systemic cardiovascular diseases such as hypertension, heart failure, and renal failure. Although, as of yet, there are no well controlled human trials proving the clinical benefits of gene therapy for cardiovascular diseases, the data presented here in animal models and in human subjects show that genetic targeting is a promising and encouraging modality, not only for the treatment and long-term control of cardiovascular diseases, but for their prevention as well.