3D printed PCL/nHAp scaffolds: Influence of scaffold structural parameters on osteoblast performance in vitro

Scaffolds play a key role in bone tissue engineering (BTE) as they provide a mechanically and biologically supportive template to treat bone defects. Yet, the ideal scaffold structures are far from certain, leaving a lot to be discovered in terms of the scaffold structure–performance relationships. In this study, we investigated the influence of pore size and internal structure on osteoblast performance in vitro. Three-dimensional (3D) scaffolds were printed from polycaprolactone (PCL) reinforced with 30% (wt.) nano-hydroxyapatite (nHAp), with two different internal structures (lattice and staggered) and four pore sizes (0.280, 0.380, 0.420, and 0.550 mm). Scaffolds were seeded with pre-osteoblast cells (MC3T3-E1). Metabolic activity of cells, osteoblast differentiation, and capability of osteoblasts to deposit mineralized matrix were examined in vitro. Staggered scaffolds better supported cellular performance. The pore size of 0.280 mm was more favorable to support cell proliferation while the pore size ≥0.420 mm was more effective to promote osteoblast differentiation and mineralization. Findings revealed that osteoblast activities were affected differently by the pore size. Our study further suggests that the structure with a gradient pore size would be better than a single size in terms of supporting cell proliferation, differentiation, and secretion of a mineralized matrix.