Template Mineralized, Decellularized Matrix-Alginate-Based Bioink Provides Structural Reinforcement in Caprine Ex Vivo Bone Defect Model

Clinical management of critical-sized bone defects (CSDs) remains a significant surgical problem. Current bioinks fail to support initial loading on bone tissue. In this study, goat-derived decellularized matrix (DCM) was used as a template for controlled mineralization, while alginate improved the printability and cellular viability. DCM proteins acted as a natural template for hydroxyapatite (HA) crystal nucleation and growth, mimicking bone nanocomposite chemistry while enhancing structural reinforcement. HA formation on DCM template was visualized by atomic force microscopy (AFM) analysis, characteristic phosphate (PO43–) peaks in attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and the HA-specific (211) diffraction peak in X-ray diffraction (XRD). Mineralized DCM was blended with alginate to formulate printable bioinks. Rheological analysis showed dominant elastic behavior (G′ > G″), shear-thinning flow, and rapid post-shear recovery. Mechanical testing further demonstrated enhanced compressive strength in HA-DCM-alginate constructs. Bioprinting with osteoblast cells demonstrated higher cellular viability in the mineralized ink while enhancing osteogenic differentiation, via both biochemical and biophysical signaling from the mineralized-DCM ink. In an ex vivo defect model, the HA-DCM-alginate system significantly increased the compressive properties of the defect construct, providing immediate structural reinforcement at the defect site. Overall, the current mineralized bioink can provide both mechanical support and bone regeneration and holds promising potential for surgical application.