Nanoparticles Effectively Target Rapamycin Delivery to Sites of Experimental Aortic Aneurysm in Rats.

Several drugs targeting the pathogenesis of aortic aneurysm have shown efficacy in model systems but not in clinical trials, potentially owing to the lack of targeted drug delivery. Here, we designed a novel drug delivery system using nanoparticles to target the disrupted aortic aneurysm micro-structure. We generated poly(ethylene glycol)-shelled nanoparticles incorporating rapamycin that exhibited uniform diameter and long-term stability. When injected intravenously into a rat model in which abdominal aortic aneurysm (AAA) had been induced by infusing elastase, labeled rapamycin nanoparticles specifically accumulated in the AAA. Microscopic analysis revealed that rapamycin nanoparticles were mainly distributed in the media and adventitia where the wall structures were damaged. Co-localization of rapamycin nanoparticles with macrophages was also noted. Rapamycin nanoparticles injected during the process of AAA formation evinced significant suppression of AAA formation and mural inflammation at 7 days after elastase infusion, as compared with rapamycin treatment alone. Correspondingly, the activities of matrix metalloproteinases and the expression of inflammatory cytokines were significantly suppressed by rapamycin nanoparticle treatment. Our findings suggest that the nanoparticle-based delivery system achieves specific delivery of rapamycin to the rat AAA and might contribute to establishing a drug therapy approach targeting aortic aneurysm

Aortic Dissection Occurring 18 Months after Successful Endovascular Repair in an Anatomically Difficult Case of Abdominal Aortic Aneurysm

We report an autopsy case of aneurysm dissection that occurred 18 months after the implantation of a Zenith stent graft. A 94-year-old woman, who had undergone an endovascular repair with postoperative reintervention, died of shock due to retroperitoneal hematoma. An autopsy indicated that the stent graft remained firmly fixed to the native aorta, whereas the dissection occurred near the proximal edge of the stent graft but not at the point of attachment between the suprarenal stent hook and the aorta. The luminal surface of the stent graft was almost completely covered with a transparent film with an endothelial cell lining, which might reflect the tissue regeneration observed on histological examination. This was a rare case of acute aortic dissection that occurred 18 months after EVAR, in which the autopsy indicated interesting microscopic findings and the mechanisms underlying the aortic dissection. We believe that aggressive reintervention at the proximal site in elderly women might cause the dissection of the native aorta

Popliteal artery aneurysm in a 14-year-old boy with tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is rarely associated with aneurysms. We have described a patient with a popliteal artery aneurysm that was associated with TSC and occlusion of the right posterior tibial artery. The patient underwent aneurysm resection and vein graft replacement, with an uneventful postoperative course and no recurrence at 11 months of follow-up. Patients with TSC could have aneurysms in areas that will not be recognized on abdominal imaging. Physical examination of the lower extremities should be performed owing to the possibility of a popliteal artery aneurysm, and imaging studies should be performed if an aneurysm is suspected