Intraoperative Bioprinting for Craniomaxillofacial Bone Reconstruction in Rats and Sheep.

Craniomaxillofacial reconstruction is challenging due to the requirement for diverse manual surgical interventions, which significantly increase as the defect volume enlarges. To address these concerns, we utilized intraoperative bioprinting (IOB) to reconstruct cranial bone defects in surgical settings. We formulated an innovative collagen-based bioink supplemented with human adipose-derived stem cells (hADSCs) or bone morphogenetic protein-2 (BMP-2). The concentration and dispersion state of collagen along with hADSCs were precisely adjusted to enhance cytocompatibility, bioprintability, and osteogenic activities. IOB was first performed via a 3-axis bioprinter on a rat model having a critical-sized calvarial defect (39.3 mm3), which was infilled within ≈30 s and resulted in ≈90% bone coverage area in 8 weeks. Secondly, IOB was conducted on sheep calvarial defects (1,209 mm3, ≈31-fold larger compared to the rat defects) using a 6-axis robotic arm, where IOB took ≈5 min per defect. On Week 12, sheep defects treated with IOB revealed accelerated bone repair (≈80% bone coverage area) and mechanical enhancement with 240%, 235%, and 358% increments in Young's modulus, peak force, and energy compared to the non-treated group. The successful execution of IOB in small and large animal models validates the translation potential of IOB for automated surgical interventions.