Abstract
This study investigates how geometrical variations in volumetrically printed (Vol3DP) structures influence the attachment, survival, and organization of human umbilical vein endothelial cells (HUVECs) and osteosarcoma cells (143b). A gelatin methacryloyl-poly(ethylene glycol) diacrylate (GelMA-PEGDA) resin was optimized for volumetric bioprinting. Compared to GelMA, Gel-PEG enhanced printing fidelity, mechanical properties, and dimensional stability. Disc-like constructs and channels with straight or angled geometries (60°, 90°, 110°) were fabricated and cultured with both cell types for up to 14 days. Label-free holographic microscopy allowed real-time visualization of cellular protrusions, critical for adhesion and mechanosensing, without staining, enabling long-term live-cell analysis in 3D constructs. HUVECs adhered, expressed CD31, and exhibited geometry-dependent spreading, reflecting their native mechanosensitivity and alignment during vascular morphogenesis. In contrast, 143b cells spread uniformly, formed dense, geometry-independent aggregates, and showed enhanced growth in Gel-PEG compared to GelMA, consistent with their aggressive, metastatic behavior. These findings demonstrate that Gel-PEG provides a stable, biomimetic matrix suitable for high-resolution Vol3DP and that holographic microscopy enables dynamic assessment of cell-material interactions. Together, they underscore the potential of this approach for engineering vascularized tissue models and for studying mechanobiological responses in both endothelial and cancer cell systems.