Abstract 15850: Stimulation of Soluble Guanylate Cyclase Activity With Riociguat Promotes Angiogenesis and Improves Neovascularization After Hindlimb Ischemia

Background: The NO-cGMP pathway has been shown to be essential for angiogenesis, vasculogenesis and post-natal neovascularization. The key enzyme responsible for the synthesis of cGMP following binding of NO is soluble guanylate cyclase (sGC). Riociguat is the first member of a novel class of compounds known as sGC stimulators. We tested the hypothesis that stimulation of sGC with riociguat might improve neovascularization in response to ischemia. Methods/Results: In a matrigel assay in vitro , riociguat dose-dependently stimulated tubule formation in human umbilical vein endothelial cells (HUVECs). Cell migration (scratch assay) was also increased in HUVECs treated with riociguat. We used a mouse model of hindlimb ischemia to investigate the effect of riociguat on neovascularization in vivo . C57Bl/6 mice were treated by gavage with 3 mg/kg/day of riociguat (or vehicle) for a total of 28 days. After two weeks of treatment, hindlimb ischemia was surgically induced by femoral artery removal. Treatment with riociguat led to improved blood flow recovery after ischemia (Laser Doppler imaging), and increased capillary density in ischemic muscles (CD31 immunostaining). Clinically, this was associated with a significant decrease of ambulatory impairment and ischemic damages. At the molecular level, we found that riociguat treatment is associated with an increased activation of sGC, PKG-α/β, Akt and ERK1/2 both in HUVECs and in ischemic muscles. Interestingly, mice treated with riociguat also showed a 94% increase in the number of bone marrow-derived pro-angiogenic cells (PACs) compared to control mice (p Conclusions: The sGC stimulator riociguat promotes angiogenesis and improves neovascularization after ischemia. The mechanism involves activation of angiogenic pathways such as Akt and ERK1/2, together with an improvement of PAC number and functions. sGC stimulation could constitute a novel therapeutic strategy to reduce tissue ischemia in patients with severe atherosclerotic diseases.