3D-Printed Poly(Lactic-co-Glycolic Acid) Binder-Based Self-Hardening Calcium Phosphate Bone Scaffolds.

Three-dimensionally (3D)-printed alpha-tricalcium phosphate (α-TCP) scaffolds, fabricated through a low-temperature hydrothermal dissolution-precipitation process, replicate the structural and compositional features of native bone. Reinforcing hydrothermally processed α-TCP with poly(lactic-co-glycolic acid) (PLGA) as a binder has previously been shown to confer distinct mechanical advantages, supporting its potential as a viable material for bone regenerative scaffolds. Although the hydrothermal processing of α-TCP scaffolds and PLGA-based mechanical reinforcement have each been characterized individually in earlier studies, this work represents the first pre-clinical in vivo assessment of osseoconduction and biocompatibility of 3D-printed, PLGA-reinforced, self-hardening calcium phosphate scaffolds in a large translational animal model. A ceramic ink suitable for extrusion was prepared by combining a 30 wt/vol% poloxamer 407 solution with α-TCP powder at a 0.45 wt/wt ratio (CTRL). A second extrudable ink, consisting of an α-TCP ceramic suspension incorporating a 35 wt/wt% PLGA binder, was formulated at a 0.5 wt/wt ratio (EXP). Cylindrical scaffolds (6 mm × 6 mm) were fabricated at room temperature using a custom-built Direct Ink Write 3D printer, then hydrothermally treated via submersion in water and thermal consolidation at 121 °C. Osteotomies were created in the ilium of adult sheep, with two cylindrical defects (7 mm × 6 mm) per animal, each receiving either a CTRL or EXP scaffold. Animals were euthanized at 3 and 12 weeks post-surgery (