Ten steps to gene therapy for cardiovascular diseases

Gene therapeutic approaches to oxidative stress-induced cardiac disease: principles, progress, and prospects

Heart and vascular diseases continue to rank among the most frequent and devastating disorders to affect adults in many parts of the world. Increasing evidence from a variety of experimental models indicates that reactive oxygen species can play a key role in the development of myocardial damage from ischemia/reperfusion, the development of cardiac hypertrophy, and the transition of hypertrophy to cardiac failure. The recent dramatic increase in availability of genomic data has included information on the genetic modulation of reactive oxygen species and the antioxidant systems that normally prevent damage from these radicals. Nearly simultaneously, progressively more sophisticated and powerful methods for altering the genetic complement of selected tissues and cells have permitted application of gene therapeutic methods to understand better the pathophysiology of reactive oxygen species-mediated myocardial damage and to attenuate or treat that damage. Although exciting and promising, gene therapy approaches to these common disorders are still in the experimental and developmental stages. Improved understanding of pathophysiology, better gene delivery systems, and specific gene therapeutic strategies will be needed before gene therapy of oxyradical-mediated myocardial damage becomes a clinical reality.

Gene therapy of hypertensive vascular injury

Hypertension and vascular injury usually require prolonged treatment, and compliance is a key to efficacy for pharmacologically-based antihypertensive therapy. Gene therapy has the potential to be long lasting, with few side effects. Recent studies have provided promising results, in which hypertension can be treated by either augmentation of vasodilation or inhibition of vasoconstriction through gene transfer in experimental models. Gene transfer is also becoming useful for the study of mechanisms of physiologic and pathophysiologic conditions, including hypertension. In this mini-review, we summarize some recent studies in this area of research, and suggest some areas where progress is needed to advance the research toward gene therapy.

1,4-Dihydropyridine calcium channel blockers inhibit plasma and LDL oxidation and formation of oxidation-specific epitopes in the arterial wall and prolong survival in stroke-prone spontaneously hypertensive rats

BACKGROUND AND PURPOSE

Calcium-channel blockers (CCBs) reduce systolic blood pressure and stroke-related mortality in stroke-prone spontaneously hypertensive rats (SPSHR). Brain ischemia is associated with loss of intracellular antioxidants. Increased formation of oxygen radicals and oxidation of LDL may enhance arterial vasoconstriction by various mechanisms. CCBs that also exert antioxidative properties in vitro may therefore be particularly useful. To investigate such antioxidant effects in vivo, we determined several parameters of LDL oxidation in SPSHR treated with two 1,4-dihydropyridine-type (1,4-DHP) CCBs of different lipophilic properties and compared them with antioxidant-treated and untreated controls. We also tested whether these drugs decrease the formation of oxidation-specific epitopes in arteries.

METHODS

Five groups of 9 to 14 SPSHR each (aged 8 weeks) were treated with 80 mg/kg body wt per day nifedipine, 1 mg or 0.3 mg/kg body wt per day lacidipine, vitamin E (100 IU/d), or carrier for 5 weeks. A group of Wistar-Kyoto rats was used as normotensive control. Plasma samples were taken, and LDL was isolated by ultracentrifugation. Then LDL was exposed to oxygen radicals generated by xanthine/xanthine oxidase reaction (2 mmol/L xanthine+100 mU/mL xanthine oxidase), and several parameters of oxidation were determined. The presence of native apolipoprotein B and oxidation-specific epitopes in the carotid and middle cerebral arteries was determined immunocytochemically.

RESULTS

1,4-DHP CCBs completely prevented mortality. Normotensive Wistar-Kyoto rats showed less oxidation than control SPSHR. Plasma lipoperoxide levels were 0.87+/-0.27 micromol/L in control SPSHR, 0.69+/-0.19 and 0.63+/-0.20 micromol/L in the groups treated with 0.3 and 1 mg lacidipine, respectively, and 0.68+/-0.23 micromol/L in nifedipine-treated animals (P<0.05 versus control SPSHR for all values). Both CCBs significantly decreased formation of conjugated dienes and prolonged the lag time in LDL exposed to oxygen radicals. Similarly, lipoperoxides and malondialdehyde were significantly reduced (P<0.05). Reduced relative electrophoretic mobility and increased trinitrobenzenesulfonic acid reactivity of LDL from treated rats (P<0.01) also indicated that fewer lysine residues of apolipoprotein B were oxidatively modified in the presence of 1,4-DHP CCBs. Finally, these drugs reduced the intimal presence of apolipoprotein B and oxidized LDL (oxidation-specific epitopes) in carotid and middle cerebral arteries.

CONCLUSIONS

In the SPSHR model, 1,4-DHP CCBs reduce plasma and LDL oxidation and formation of oxidation-specific epitopes and prolong survival independently of blood pressure modifications. Our results support the concept that the in vivo protective effect of these drugs on cerebral ischemia and stroke may in part result from inhibition of oxidative processes.