Regeneration of severe bone defects remains a challenge. A formulation of synthetic glass-reinforced hydroxyapatite bone substitute, Bonelike® Poro (BL®P), 250500 µm-diameter, with a dextrin-based hydrogel (HG), further loaded with human dental pulp stem cells (hDPSCs) with osteogenic differentiation ability, was tested for the management of critical-sized defects in an ovine model. Morphology, calcium release, and mechanical strength of HG + BL®P were analyzed. Then, BL®P, HG + BL®P, and 106 hDPSCs-loaded HG + BL®P were implanted in ovine critical-sized 14 mm-diameter calvaria defects. Bone samples were collected after 3 and 6 weeks for histological and micro-CT analysis. BL®P exhibits a suitable porous size for cell ingrowth, from the nm (>200 nm) to the µm (5 µm) range. The addition of BL®P granules to the HG resulted in increased compressive elastic modulus and ultimate tensile strength. The mildly acidic nature of the HG contributed to a faster dissolution of granules. In vivo results confirmed the HG suitability as a carrier, providing better defect filling, easy handling, and injectability of BL®P without compromising new bone formation nor biocompatibility. The HG + BL®P formulations can successfully regenerate critical-sized defects; however, addition of hDPSCs did not significantly enhance new bone formation under these conditions. Granular BL®P provides an effective alternative to autologous grafts. The HG acts as a biocompatible carrier of granular bone substitutes and cells, conferring injectability and cohesivity.Alexandra Machado and Isabel Pereira were supported by the grants SFRH/BD/132000/2017 and UMINHO/BI/131/2018 respectively, from Portuguese Foundation for Science and Technology (FCT), Portugal. The authors acknowledge the funding from FEDER and NORTE 2020 through the project no. 003262 titled “iBONE therapies: advanced solutions for bone regeneration”. This study was supported by FCT under the scope of the strategic funding of UID/BIO/04469 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte 2020 - Programa Operacional Regional do Norte. The participation of Isabel Pires, Justina Prada, Luís Maltez and José Eduardo Pereira was funded by the projects UIDB/CVT/00772/2020 and LA/P/0059/2020 supported by FCT. The participation of Rui Alvites, Ana Catarina Sousa, Mariana Branquinho, Ana Rita Caseiro, Sílvia Santos Pedrosa and Ana Colette Maurício was funded by Projects PEst-OE/AGR/UI0211/2011, UIDB/CVT/00772/2020 and LA/P/0059/2020. Mariana Vieira Branquinho (SFRH/BD/146172/2019) and Ana Catarina Sousa (SFRH/BD/146689/2019) acknowledge FCT, for financial support.info:eu-repo/semantics/publishedVersio
