An alternative
intracranial aneurysm embolic agent is emerging in the form of
hydrogels due to their ability to be injected in liquid phase and solidify in situ.
Hydrogels have the ability to fill an
aneurysm sac more completely compared to solid implants such as those used in coil embolization. Recently, the feasibility to implement photopolymerizable
poly(ethylene glycol) dimethacrylate (
PEGDMA) hydrogels in vitro has been demonstrated for
aneurysm application. Nonetheless, the physical and mechanical properties of such
hydrogels require further characterization to evaluate their long-term integrity and stability to avoid implant compaction and
aneurysm recurrence over time. To that end, molecular weight and
polymer content of the
hydrogels were tuned to match the elastic modulus and compliance of aneurysmal tissue while minimizing the swelling volume and pressure. The
hydrogel precursor was injected and photopolymerized in an in vitro
aneurysm model, designed by casting
polydimethylsiloxane (PDMS) around 3D printed water-soluble sacrificial molds. The
hydrogels were then exposed to a
fatigue test under physiological pulsatile flow, inducing a combination of circumferential and shear stresses. The
hydrogels withstood 5.5 million cycles and no significant
weight loss of the implant was observed nor did the polymerized
hydrogel protrude or migrate into the parent artery. Slight surface erosion defects of 2-10 μm in depth were observed after loading compared to 2 μm maximum for non-loaded
hydrogels. These results show that our fine-tuned photopolymerized
hydrogel is expected to withstand the physiological conditions of an in vivo implant study.