Extrusion-based 3D-printed “rolled-up” composite scaffolds with hierarchical pore structure for bone growth and repair

Three-dimensional (3D) bioprinting, specifically direct ink writing (DIW) capable of printing biologically active substances such as growth factors or drugs under low-temperature conditions, is an emerging direction in bone tissue engineering. However, limited by the bio-ink mobility and the poor resolution of this printing technology, the lateral pores of current crisscross-stacked scaffolds printed through DIW tend to clog and are inimical to bone growth. Therefore, it is critical to develop DIW printed biological scaffold structure with high mechanical strength, porosity, and biocompatibility performance. Herein, patterned polylactic acid (PLA)/polycaprolactone (PCL)/nano-hydroxyapatite (n-HA) based scaffold was printed through DIW technological and rolled-up for properties characterization, cytocompatibility test, and bone repair experiment. The result not only shows that the hexagonal patterned scaffolds are mechanically strong with porosity, but also demonstrated that the hierarchical pore structure formed during rolled-up has the potential to address the clogging problem and stimulates bone growth and repair.