Modification of 3D printed PCL scaffolds by PVAc and HA to enhance cytocompatibility and osteogenesis

In the study, a specific material system that contains poly-(ε-caprolactone) (PCL), polyvinyl acetate (PVAc) and hydroxyapatite (HA) was used to fabricate porous scaffolds employing a 3D printing technique for bone regeneration. Four groups of 3D printing scaffolds were fabricated: PCL, PCL/PVAc, PCL/HA and PCL/PVAc/HA for comparision. The morphologies, mechanical properties and biological characteristics of these scaffolds were analyzed using SEM, a material testing machine, in vitro cell culture and in vivo animal experiments. The results showed that these 3D printed scaffolds possessed porous channel structures with a hole size of 375-475 μm and porosity of 74.1-76.1%. The compressive moduli of the scaffolds increased with the addition of HA and decreased with the addition of PVAc. The PCL/PVAc/HA scaffold exhibited higher cell proliferation and bone formation rates than other groups (p < 0.001), which could be attributed to the synergistic effect of PAVc and HA components. Two types of new bone formation patterns in the scaffold were found in this study: one is the new bone formed directly on the grid matrix, and the other is the new bone initially formed in the center of the scaffold channel and then remolded to concentric circles. The osteogenesis pattern of the latter is analogous to the osteon structure of a cortical bone. The 3D printed scaffold based on PCL/PVAc/HA tri-component system is a promising prospect for future individualized bone repair applications.