Angiogenic properties of human endothelial colony-forming cells in Granulomatosis with Polyangiitis

Abstract

BACKGROUND Endothelial progenitor cells are essential for vascular homeostasis. Considering the recurrent nature of granulomatosis with polyangiitis (GPA) the aim of the study was to evaluate the angiogenic capacity of endothelial colony-forming cells (ECFC), which have the capacity for neovasculogenesis in vitro, of the patients with GPA, before and after plasma stimulation. METHODS Thirteen GPA PR3-positive patients and 15 healthy controls were included. ECFC were isolated from periferic blood and characterized by flow cytometry (FACS). Capillary tube formation (Matrigel assay) and scratching assay were measured during 24 hours. The migration assay was also performed after overnight incubation with healthy control plasma and active GPA patient plasma. Three patients with active disease where submitted to recollection of ECFC after treatment for longitudinal evaluation. RESULTS The culture was successful in 62% of GPA patients and 57% of controls. In the matrigel assay the ECFC from patients and controls showed similar capillary structures formation, however ECFC from inactive GPA alone showed early loss of angiogenic capacity between 15 and 24 hours. In scratching assay, there was an impairment in the proliferative capacity of the ECFC between GPA patients and controls without significant difference (12th hour, p = 0.05). When incubated with control plasma, ECFC of remission GPA patients showed a significant lower migration capacity after the 4th hour (p = 0.0001). In longitudinal analysis, ECFC isolated after treatment showed significantly lower migration rates. CONCLUSIONS PR3-positive remission GPA ECFC demonstrated early loss of tube formation and less proliferative capacity compared to those of healthy controls, suggesting impairment of endothelial function.