Endothelial microparticles affect angiogenesis in vitro: role of oxidative stress

Abstract

Endothelium-derived microparticles have recently been described as a new marker of endothelial cell dysfunction. Increased levels of circulating microparticles have been documented in inflammatory disorders, diabetes mellitus, and many cardiovascular diseases. Perturbations of angiogenesis play an important role in the pathogenesis of these disorders. We demonstrated previously that isolated endothelial microparticles (EMPs) impair endothelial function in vitro, diminishing acetylcholine-induced vasorelaxation and nitric oxide production by rat aortic rings and simultaneously increasing superoxide production. Herein, using the Matrigel assay of angiogenesis in vitro and a topological analysis of the capillary-like network by human umbilical vein endothelial cells (HUVECs), we investigated the effects of EMPs on formation of the vascular network. All parameters of angiogenesis were affected by treatment for 48 h with isolated EMPs in a concentration of 10(5) but not 10(3) or 10(4) EMPs/ml. The effects included decreases in total capillary length (24%), number of meshes (45%), and branching points (36%) and an increase in mesh area (38%). The positional and topological order indicated that EMPs affect angiogenic parameters uniformly over the capillary network. Treatment with the cell-permeable SOD mimetic Mn(III)tetrakis(4-benzoic acid) porphyrin chloride (Mn-TBAP) partially or completely restored all parameters of angiogenesis affected by EMPs. EMPs reduced cell proliferation rate and increased apoptosis rate in time- and dose-dependent manners, and this phenomenon was also prevented by Mn-TBAP treatment. Our data demonstrate that EMPs have considerable impact on angiogenesis in vitro and may be an important contributor to the pathogenesis of diseases that are accompanied by impaired angiogenesis.

Microvesicles and diabetic complications — novel mediators, potential biomarkers and therapeutic targets

“…Taraboletti et al demonstrated that although the low concentrations of MVs isolated from HUVECs promote angiogenesis in vitro, the high concentrations of endothelial-derived MVs suppress angiogenesis [83] . In accordance with these results, Mezentsev and colleagues reported that isolated endothelial-derived MVs in pathophysiological concentrations impair angiogenesis in vitro by affecting all parameters of capillary-like network formation [84] . In addition, the MVs isolated from T2DM patients with CAD fail to induce angiogenesis, which may partially explain the lack of vascular regeneration characterization in T2DM with CAD [35] .…”

Endothelial microparticles: a universal marker of vascular health?

“…Indeed, low concentrations of EMPs have been observed to have proangiogenic properties by regulation activity of matrix metalloproteinases produced by endothelial cells. 11 In contrast, high concentrations of EMPs decreased the formation of capillary-like structures by stimulation of the production of reactive oxygen species and thus showing antiangiogenic properties. 12 Jimenez et al have suggested that analysis of EMP phenotypic profile may provide clinically useful information on the status of the endothelium.…”

Circulating Microparticles

“…60 Further details on the molecular mechanisms of MP effects on vascular reactivity can be found in Martinez et al 64 Finally, endothelial, platelet, and tumor cell-derived MPs seem to be able to stimulate angiogenesis, an effect mediated by reactive oxygen species, metalloproteinases, growth factors such as vascular endothelial growth factor, or sphingomyelin. [65][66][67][68][69] Apoptotic bodies from endothelial cells (larger than MPs) could also contribute to tissue repair mechanisms by stimulating the differentiation of progenitor cells. 70 …”