<br/>Cerebral aneurysms are weak areas in the walls of an artery that can rupture and lead to high mortality rates. A majority of cerebral aneurysms are currently treated with minimally invasive catheter-based techniques, particularly endovascular coiling. However, these devices show unfavorable primary outcomes in 20-30% of cases. We are engineering an injectable, in situ cross-linkable, shape-conforming, intrasaccular porous scaffold that harnesses the unique behavior of the reverse thermo-responsive polymer FDMA (F127-dimethacrylate), thereby enhancing clinical performance. In this project, we focus on optimizing gel and catalyst concentration so that the treatment can withstand the shear stress present in the carotid artery while also being easily injectable. We also discuss differences between two crosslinkers, FeCl2 and FeCl3, to understand which is optimal. Varying concentrations of FDMA were synthesized in combination with varying concentrations of FeCl2 catalyst or FeCl3 catalyst. These polymers are liquid at low temperatures and transition to gels at higher temperatures. Rheological testing was conducted to determine which gel would exhibit the greatest elastic modulus, allowing for the greatest strength, while also transitioning to a micelle gel at the appropriate temperature (~20°C). Additionally, we simulated injection of the gel into real patient aneurysms by using a 3D silicone model aneurysm that was connected to peristaltic pumps mimicking pulsatile flow in the carotid artery. Injections were imaged via angiography and a biocompatible iohexol radiopaque agent. 28.9% FDMA and 0.25x concentration of FeCl2 exhibited the greatest modulus of 223.6 kPa and a retention time of 7 weeks inside the model aneurysm. Pure 28.9% FDMA had a transition temperature of 16 °C. With each tested catalyst concentration, FeCl3 and FeCl2 displayed similar moduli, although FeCl2 consistently displayed slightly higher moduli. Additionally, both gels demonstrated their greatest elastic modulus at 0.25x concentration catalyst. Thus, 28.9% FDMA and 0.25x FeCl2 was found to be the optimal gel and catalyst concentration that is best able to resist shear and deformation inside the aneurysm while also being easily injectable.

Optimizing crosslinked hydrogels for brain aneurysm treatment

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.