Transendothelial migration of ferric ion in FeCl3 injured murine common carotid artery

Introduction/Objectives Adventitial application of FeCl3 causes endothelial injury, platelet aggregation, and a rapid onset of thrombus formation. The transmigration pathway of the ferric ion has not been definitively identified. Using a combination of TEM and X-ray elemental analysis, this study aims to elucidate the endothelial pathway of ferric ion migration in carotid artery. Methods and results Vascular injury was induced by placing a Whatman #1 filter paper strip saturated with 10% FeCl3 over the common carotid artery in male C57BL/6 mice for 3 min. After rinsing in saline, the mice were terminated at 10 or 30 min. The FeCL3 exposed segments of the common carotid artery were dissected, and processed for TEM. Thrombus formation was observed in all cases. Endothelial and smooth muscle injuries were observed in segments of the vessel in direct contact with the oxidant. The endothelial injury ranged from minimal damage to total denudation. The basal endothelial surface adjacent to the internal elastic lamina showed accumulation of electron opaque vesicles. The membrane enclosed particles transmigrated across the endothelium and exocytosed into the lumen. The nature of the particles shown by STEM/EDS was rich in ferric ion. Elemental analysis also showed that some ferric oxide aggregates formed near the developing thrombus in the vascular lumen. Conclusion Our results showed the ferric ion permeated the endothelial basal lamina before entering the arterial lumen via endocytic–exocytic pathway. This study provides an ultrastructural framework for future analysis of the adluminal and luminal injuries in this model.