Reconstruction of a Segmental Bone Defect Using Vascularized Tissue-Engineered Bone Substitutes: An Animal Study

Repairing large segmental bone defects remains a major challenge in orthopedics, with conventional autografting and allografting limited by donor shortages and high complication rates. Tissue-engineered bone substitutes have emerged as a potential solution. This study aimed to assess the vascular regeneration of dual-vascularized tissue-engineered bone substitutes in the reconstruction of large segmental bone defects in rabbits. Demineralized bone matrix (DBM) was used as a scaffold, with endothelial progenitor cells (EPCs) seeded onto it. A vascular channel was created within the DBM-EPCs composite scaffold, and the radial artery was implanted into this channel. New Zealand white rabbits were used to create a large radial bone defect model, with animals divided into four groups: DBM, DBM+EPCs, DBM+Vascular Bundle, and DBM+EPCs+Vascular Bundle (n=9 per group). X-ray examinations, gross morphological observations, and CD31 immunofluorescence staining were conducted at 4, 8, and 12 weeks post-surgery. Micro-CT was used to reconstruct the three-dimensional structures of the defects after 12 weeks. The DBM+EPCs+Vascular Bundle group demonstrated the most significant bone regeneration and vascularization across all time points. X-ray, gross morphology, Micro-CT analysis, HE staining, and CD31 immunofluorescence staining all revealed superior bone regeneration and vascular density in this group compared to the others. In conclusion, the dual vascularization strategy significantly enhanced bone regeneration and angiogenesis in the reconstruction of large bone defects.