Biomimetic vascularized adipose-derived mesenchymal stem cells bone-periosteum graft enhances angiogenesis and osteogenesis in a rabbit spine fusion model

BackgroundSeveral artificial bone grafts have been developed for bone reconstruction but fail to achieve anticipated osteogenesis due to their insufficient neovascularization capacity. Besides, periosteum plays an essential role in the neovascularization process in bone formation and healing. The aim of this study was to develop a cell-based biomimetic vascularized bone-periosteum construct (VBPC) to provide better neovascularization for osteogenesis and bone regeneration.MethodsTwenty-four male New Zealand white rabbits were divided into four groups according to the experimental materials. We first cultured adipose-derived mesenchymal stem cells (AMSCs) and seeded them evenly in the collagen/chitosan sheet to form an AMSCs-sheet-engineered periosteum. Simultaneously, the AMSCs were seeded onto alginate scaffolds and were cultured to differentiate to endothelial-like cells to form vascularized bone constructs (VBC). The success of endothelial differentiation was confirmed by real-time polymerase chain reaction and immunofluorescence staining analysis. The AMSCs-sheet-engineered periosteum was wrapped onto VBC to create biomimetic VBPC, which was then implanted in bilateral L4-5 intertransverse space of rabbit. The acellular alginate-sheet construct, VBC, and non-vascularized AMSCs-alginate-periosteum construct were used as controls. At 12 weeks after implantation, the bone-forming capacities of the constructs were determined by computed tomography, biomechanical testing, histology, and immunohistochemistry staining analyses.ResultsTwelve weeks after implantation, the VBPC group significantly increased new bone formation volume than the control groups. Biomechanical testing demonstrated a higher torque strength in the VBPC group, and suggested that the cell sheet played a critical role for mechanical support. Notably, the hematoxylin and eosin, Masson’s trichrome, and immunohistochemistry stained histologic results revealed that the VBPC group promoted the formation of blood vessels and new bones in the L4-5 intertransverse fusion areas.ConclusionsThe tissue-engineered biomimetic VBPC showed great capability in promoting angiogenesis and osteogenesis in vivo. The VBPC may overcome the deficits of traditional bone grafts. These findings suggest a novel approach to improve the timely formation of blood vessels from bone substitutes and provide an ideal source for bone regeneration.