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.修复大型节段性骨缺损仍是骨科领域的重大挑战，传统自体骨移植与同种异体骨移植均受限于供体短缺与较高并发症发生率。组织工程骨支架已成为潜在的解决方案。本研究旨在评估双血管化组织工程骨支架在兔大型节段性骨缺损重建中的血管再生效果。本研究以脱钙骨基质（demineralized bone matrix, DBM）作为支架，并将内皮祖细胞（endothelial progenitor cells, EPCs）接种于其上，在DBM-EPC复合支架内构建血管通道，将桡动脉植入该通道中。选用新西兰大白兔构建桡骨大型骨缺损模型，将实验动物分为四组：DBM组、DBM+EPCs组、DBM+血管束组以及DBM+EPCs+血管束组（每组n=9）。分别于术后4周、8周及12周进行X射线检查、大体形态观察以及CD31免疫荧光染色；术后12周利用Micro-CT对缺损区域进行三维结构重建。结果显示，DBM+EPCs+血管束组在所有时间点均表现出最为显著的骨再生与血管化效果；X射线检查、大体形态观察、Micro-CT分析、HE染色以及CD31免疫荧光染色结果均表明，该组的骨再生效果与血管密度均优于其余各组。综上，双血管化策略可显著促进大型骨缺损重建过程中的骨再生与血管生成。