Abstract
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.
Highlights
An intracranial aneurysm is an outpouching of a cerebral artery which may be present in ∼4% of the population (Keedy, 2006)
The swelling ratio increased with the poly(ethylene glycol) dimethacrylate (PEGDMA) molecular weight and remained stable over the course of the experiment of 28 days (Figure 3A)
The swelling ratio was significantly reduced within the constrained aneurysm model compared to free samples (e.g., 58 vs. 151% for PEGDMA20k-10, respectively), due to the limited medium absorption into the network of the hydrogel
Summary
An intracranial aneurysm is an outpouching of a cerebral artery which may be present in ∼4% of the population (Keedy, 2006). Aneurysm rupture is associated with a high rate of mortality and severe morbidity, thereby requires effective treatment (Medical Advisory Secretariat, 2006). Endovascular therapy, essentially coil embolization, may be performed acutely after an aneurysm rupture or electively to prevent bleeding. Usually
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