Evaluation of triply periodic minimal surface geometries in 3D-printed PLA scaffolds for chondrogenic differentiation

Triply periodic minimal surface (TPMS) scaffolds are gaining attention in tissue engineering due to their continuous and interconnected porous architecture. In this study, three TPMS geometries-Gyroid, Diamond, and I-WP-were fabricated from polylactic acid (PLA) using fused deposition modeling (FDM), with all scaffolds designed to maintain the same overall porosity. Scaffold characterization included scanning electron microscopy (SEM), microcomputed tomography (micro-CT), compressive mechanical testing, and surface wettability analysis. Although porosity was constant, differences in Equivalent Circular Diameter (ECD) values were observed among the geometries, reflecting variations in pore morphology. Adipose-derived stem cells (ADSCs) were seeded onto the scaffolds and cultured under chondrogenic differentiation conditions for 21 days. Cell viability, gene expression (Col2, Col10, Sox9), and protein levels were assessed using RT-PCR and Western blot. All scaffold geometries supported cell attachment and chondrogenic differentiation to varying degrees. The Diamond geometry showed the highest chondrogenic marker expression at the mRNA level, while the Gyroid geometry promoted more stable protein expression with reduced hypertrophic signaling. These findings demonstrate that scaffold geometry, even under identical material and porosity conditions, can influence stem cell behavior. The results offer valuable insights for optimizing TPMS-based scaffold designs in cartilage tissue engineering applications.