MRI-to-Synthetic 3D Gel Brain: Proof-of-Concept Fabrication For Intra-Parenchymal Diffusion Studies

Bioprinting technologies utilize hydrogel-based biomaterials to more accurately depict in vivo physical conditions within in vitro studies, yet, manufacturing the human brain from soft, poroelastic hydrogels remains a fundamental challenge. Conventional manufacturing routes to fabricate hydrogel brain models using techniques, i.e., 3D printing, seems challenging. This study aims to demonstrate an inverse replica molding fabrication technique that can overcome these challenges while maintaining the complex shape of an individual subjects brain in a miniaturized model--allowing for a more robust hydrogel model that can capture the interactions between diffusing molecules and brain boundaries. This is done by taking a subjects magnetic resonance imaging (MRI) scan and reconstructing the outer pial surface into a mesh surface. The mesh was then converted to an STL and printed out using an extrusion printer. A silicon mold was made from this print into which agarose was gelled. Once fully gelated, the synthetic gel brain was then carefully removed. Two infusion trials were run in the gel brain, each using a different infusion site. Then a diffusion profile was established and compared to a simple gel infusion model. The result shows different diffusion profiles at each location and between the simple and complex models. This model can better represent the interference the complex shape of the brain has on particle movement compared to simple gel models.