A new injectable radiopaque chitosan-based sclerosing embolizing hydrogel for endovascular therapies

Endovascular repair of abdominal aortic aneurysms with a stent graft is limited by the persistence or recurrence of endoleaks. These are believed to be related to the recanalization of the aneurismal sac by endothelialized neochannels, which could lead to late type I and II endoleaks. Embolization has been proposed to treat or prevent endoleaks, but presently commercialized embolizing materials have several drawbacks and do not fully prevent endoleak recurrence. A novel chitosan hydrogel that is injectable, radiopaque and contains sodium tetradecyl sulfate (STS), a well-known sclerosing agent, was developed in order to combine blood flow occlusion and endothelium ablation properties. chitosan/STS hydrogels were characterized and optimized using rheometry, scanning electron microscopy, swelling and ex vivo embolization assay. They were shown to exhibit rapid gelation and good mechanical properties, as well as sclerosing properties. Their potential for the embolization of aneurysms was subjected to preliminary in vivo evaluation in a bilateral iliac aneurysm model (three dogs) reproducing persistent endoleaks after endovascular aneurysm repair (EVAR). At 3 months no endoleak was detected in any of the three aneurysms treated with chitosan/STS hydrogels. In contrast, type I endoleaks were detected in two of the three aneurysms treated with chitosan hydrogels. Generally, chitosan/STS hydrogels have great potential as embolizing and sclerosing agents for EVAR and possibly other endovascular therapies.