The effects of different vascular carrier patterns on the angiogenesis and osteogenesis of BMSC-TCP-based tissue-engineered bone in beagle dogs.

Bone repair using tissue-engineered bone (TEB) in a large defect or accompanied by a poor recipient vascular bed is a long-standing challenge. Surgical vascular carrier patterns of vascular bundle (VB) and arteriovenous loop (AV loop) have been shown to improve the vascularization and repair capacity of TEB. However, the effects of these different vascular carrier patterns on angiogenesis and osteogenesis in TEB have never been evaluated. Here, TEB was constructed with bone marrow mesenchymal stem cells (BMSCs) and β-TCP and prevascularized by the VB or AV loop technique in beagle dogs. The vascularization and bone formation in TEB were quantitatively compared using Microfil perfusion, histological examination and CT and micro-CT analyses. The distribution and constitution of the neovasculature were analysed to determine the underlying mechanism of angiogenesis. The results showed that prevascularized TEB generated bone tissue faster and more homogeneously than untreated TEB. The VB technique was found to strike a better balance between bone regeneration and β-TCP scaffold degradation than the AV loop strategy, which resulted in more vascularization but less bone yield, due to faster degradation of the β-TCP scaffold. This study indicates that a suitable triangular relationship, composed of bone regeneration, scaffold degradation and vasculature, is critical to TEB construction.