The study was conducted in cultured human umbilical vein endothelial cells (HUVECs) and adult female Balb/c mice using several techniques.
RESULTS: In vitro, both SiNP-20 and SiNP-100 decreased the viability and damaged the plasma membrane of cultured HUVECs. The nanoparticles also inhibited HUVECs migration and tube formation in a concentration-dependent manner. Both SiNPs induced significant
calcium mobilization and generation of
reactive oxygen species (ROS), increased the phosphorylation of vascular endothelial (
VE)-cadherin at the site of
tyrosine 731 residue (pY731-VEC), decreased the expression of
VE-cadherin expression, disrupted the junctional
VE-cadherin continuity and induced
F-actin re-assembly in HUVECs. The
injuries were reversed by blocking Ca2+ release activated Ca2+ (
CRAC) channels with YM58483 or by eliminating ROS with N-acetyl
cysteine (NAC). In vivo, both SiNP-20 and SiNP-100 (i.v.) induced multiple organ
injuries of Balb/c mice in a dose (range 7-35 mg/kg), particle size, and exposure time (4-72 h)-dependent manner.
Heart injuries included coronary endothelial damage, erythrocyte adhesion to coronary intima and coronary coagulation. Abdominal aorta injury exhibited intimal
neoplasm formation.
Lung injuries were smaller pulmonary vein coagulation, bronchiolar epithelial
edema and lumen oozing and narrowing. Liver
injuries included multifocal
necrosis and smaller hepatic vein congestion and coagulation. Kidney
injuries involved glomerular congestion and swelling. Macrophage infiltration occurred in all of the observed organ tissues after SiNPs exposure. SiNPs also decreased
VE-cadherin expression and altered
VE-cadherin spatial distribution in multiple organ tissues in vivo. The largest SiNP (SiNP-100) and longest exposure time exerted the greatest toxicity both in vitro and in vivo.
CONCLUSIONS: SiNPs, administrated in vivo, induced multiple organ
injuries, including endothelial damage, intravascular coagulation, and secondary
inflammation. The
injuries are likely caused by upstream Ca2+-ROS signaling and downstream
VE-cadherin phosphorylation and destruction and
F-actin remodeling. These changes led to endothelial barrier disruption and triggering of the contact coagulation pathway.