Microparticles are small fragments generated from the plasma membrane after cell stimulation. Among the candidate proteins harboured by microparticles, we have recently shown that Sonic Hedgehog is present in MPs generated from activated/apoptotic human T CEM lymphocytes (1). Microparticles were isolated following serial centrifugations. Eahy 926 endothelial cells were grown for 24h in absence or presence of 10 µg/mL microparticles pre-incubated or not either with PI3-kinase inhibitor (LY294002, 20 µM), MEK 1/2 inhbibtor (U0126, 10 µM), cyclopamine (30 µM), a specific antagonist of the Sonic Hedgehog receptor (Patched), or siRNA of Patched. Cell lysates were analyzed by Western blot. Also, cells were used for direct measure of nitric oxide, whereas oxidative stress was determined by flow cytometry. In another set of experiments, after 24h of intravenous injection of microparticles into mice, endothelium-dependent relaxation was determined in aortic rings. Also, ischemia/reperfusion was induced in mice by ligating the left anterior descending coronary artery proximal to its origin and endothelial function of distal coronary artery was assessed. Finally, the effect of microparticles on angiogenesis was determined by Matrigel assays and vessel sprouting in mice aortic rings. Here, we show that Sonic Hedgehog carried by microparticles induces nitric oxide release from endothelial cells at the basal level and after a bradykinin-stimulation (20 µM) (2.47 and 2.6 fold, respectively) and triggers changes in both the expression and the phosphorylation of enzymes related to the nitric oxide pathway, and also decreases production of reactive oxygen species (38.6±1.4 % of positive cells in treated vs. 51.4±0.2 % in control). When PI3-kinase and ERK signalling were specifically inhibited, the effects of microparticles were reversed. In vivo injection of microparticles in mice was also able to improve endothelial function (EC50; 5,3e-008 M of acetylcholine in control vs. 6,5e-008 M in treated mice) by increasing nitric oxide release (1.4, 1.92 and 2.6-fold in blood, hearth and lung, respectively) and it reversed endothelial dysfunction after ischaemia/reperfusion. Silencing the effects of Sonic Hedgehog with either cyclopamine or siRNA of Patched, strongly reduced production of nitric oxide elicited by microparticles (34.6%) in endothelial cells. Finally, microparticles promotes angiogenesis, these effects being abolished by Sonic Hedgehog pathway inhibition. Taken together, we propose that the biological message carried by microparticles harbouring Sonic Hedgehog may represent a new therapeutic approach against endothelial dysfunction during acute severe endothelial injury.