3D-Printing and Long-Term High-Activity Culture In Vitro of a Cell-Loaded Perfusable Brain-like Scaffold Based on Fractal Geometry

A brain-mimetic scaffold that merges fractal cortex topology with hierarchical perfusion channels was fabricated to sustain a high viability in thick neural constructs. An 8% (w/v) methacrylated gelatin (GelMA)/2% (w/v) methacrylated hyaluronic acid/1% (w/v) methacrylated silk fibroin/3% (w/v) gelatin hydrogel supporting NE-4C neural stem cell proliferation, adhesion, and Digital Light Processing (DLP) bioprinting was developed. Human-brain computed tomography (CT) data were reconstructed, and box-counting verified folded fractal geometry ( D = 1.35–1.37). A perfusable hollow scaffold with a wall thickness of 1.5 mm and interconnected channels was accordingly designed and printed in one step by alternating batch exposure with on-demand resin replenishment. After 28 days of static culture, viability reached 92.8%; this high cell survival rate was primarily attributed to the scaffold’s fractal topological structure. A closed-loop perfusion system was established for the brain-like scaffold. Closed-loop perfusion speed at 2 mL/min further improved viability by 6% and proliferation by 14%, whereas perfusion at 8 mL/min decreased them by 25% and 6%. This investigation provides a scalable biomimetic platform for constructing functional neural organoids, screening neurotoxic drugs, and repairing personalized brain tissue repair.