Response to a letter to the editor by Satvika Uppu

The NO-donor MPC-1011 stimulates angiogenesis and arteriogenesis and improves hindlimb ischemia via a cGMP-dependent pathway involving VEGF and SDF-1α

BACKGROUND AND AIMS

Peripheral arterial disease (PAD) is an important cause of morbidity and mortality with little effective medical treatment currently available. Nitric oxide (NO) is crucially involved in organ perfusion, tissue protection and angiogenesis.

METHODS

We hypothesized that a novel NO-donor, MPC-1011, might elicit vasodilation, angiogenesis and arteriogenesis and in turn improve limb perfusion, in a hindlimb ischemia model. Hindlimb ischemia was induced by femoral artery ligation in Sprague-Dawley rats, which were randomized to receive either placebo, MPC-1011, cilostazol or both, up to 28 days. Limb blood flow was assessed by laser Doppler imaging.

RESULTS

After femoral artery occlusion, limb perfusion in rats receiving MPC-1011 alone or in combination with cilostazol was increased throughout the treatment regimen. Capillary density and the number of arterioles was increased only with MPC-1011. MPC-1011 improved vascular remodeling by increasing luminal diameter in the ischemic limb. Moreover, MPC-1011 stimulated the release of proangiogenic cytokines, including VEGF, SDF1α and increased tissue cGMP levels, reduced platelet activation and aggregation, potentiated proliferation and migration of endothelial cells which was blunted in the presence of soluble guanylyl cyclase inhibitor LY83583. In MPC-1011-treated rats, Lin^-/CD31⁺/CXCR4⁺ cells were increased by 92.0% and Lin^-/VEGFR2⁺/CXCR4⁺ cells by 76.8% as compared to placebo.

CONCLUSIONS

Here we show that the NO donor, MPC-1011, is a specific promoter of angiogenesis and arteriogenesis in a hindlimb ischemia model in an NO-cGMP-VEGF- dependent manner. This sets the basis to evaluate and confirm the efficacy of such therapy in a clinical setting in patients with PAD and impaired limb perfusion.

Basic in vitro Characterization of the Vasodilatory Potential of 2-Aminoethyl Nitrate Fixed-Dose Combinations with Cilostazol, Metoprolol and Valsartan

BACKGROUND/AIMS

2-aminoethyl nitrate (CLC-1011) is a member of the class of organic nitrates that cause vasodilation by the generation of nitric oxide (•NO). These drugs are mainly used for the treatment of angina pectoris and ischemic heart disease. The aim of this study was to characterize the vasodilatory potency of this organic nitrate alone and in combination with clinically established cardiovascular drugs.

METHODS

Vasodilation by CLC-1011 was tested by isometric tension studies, either alone or combined with cilostazol, valsartan, and metoprolol. Induction of oxidative stress in isolated heart mitochondria was measured by enhanced chemiluminescence. Bioactivation of CLC-1011 in aortic tissue was measured by electron paramagnetic resonance spectroscopy using an iron-based spin trap for •NO.

RESULTS

We observed potent vasodilation by CLC-1011 and additive effects for all three drug combinations. In contrast to nitroglycerin (GTN), CLC-1011 did not stimulate mitochondrial oxidative stress. CLC-1011 was bioactivated to •NO in aortic tissue.

CONCLUSION

In summary, the experiments described in this report demonstrate that CLC-1011 does not induce oxidative stress, is a more potent vasodilator than isosorbide-5-mononitrate and dinitrate ISDN, and displays synergistic vasodilation with other cardiovascular drugs. CLC-1011 fixed dose combinations could be used in the management of cardiovascular diseases.