In vivo engineering of a human vasculature for bone tissue engineering applications

Abstract

The neovascularization of three-dimensional voluminous tissues, such as bone, represents an important challenge in tissue engineering applications. The formation of a preformed vascular plexus could maintain cell viability and promote vascularization after transplantation. We have developed a three-dimensional spheroidal coculture system consisting of human primary endothelial cells and human primary osteoblasts (hOBs) to improve angiogenesis in bone tissue engineering applications. In this study, we investigated the survival and vascularization of the engineered implants in vivo. Endothelial cell spheroids were cocultured with hOBs in fibrin and seeded into scaffolds consisting of processed bovine cancellous bone (PBCB). The cell-seeded scaffolds were evaluated for their angiogenic potential in two different in vivo assays: the chick embryo chorioallantoic membrane (CAM) model and the severe combined immunodeficiency disorder (SCID) mouse model. In both assays, the development of a complex three-dimensional network of perfused human neovessels could be detected. After subcutaneous implantation into immunodeficient mice, the newly formed human vasculature was stabilized by the recruitment of murine smooth muscle α-actin-positive mural cells and anastomoses with the mouse vasculature. We conclude that this endothelial cell spheroid system can be used to create a network of functional perfused blood vessels in vivo. The finding that this process takes place with high efficacy in the presence of co-implanted primary osteoblasts and in an osteoconductive environment provided by the PBCB scaffold, suggests that this system may be suitable for improving vascularization in bone tissue engineering.

A review of fibrin and fibrin composites for bone tissue engineering

“…42 In another study, Steffens et al co-seeded human endothelial cells and primary osteoblasts into PBCBbased scaffolds to investigate whether a blood vessel network which was created by endothelial cells may enhance survival of osteogenic cells. 43 Despite some preliminary promising results toward the formation of a 3D network of perfused human neovessels in chick embryo chorioallantoic membrane and subcutaneous mouse models, promotion of bone repair was not detected in the calvarial bone defects in mice. The authors postulated that endogenous neovascularization in the defects may have been sufficient to sustain osteogenesis.…”

“…[34][35][36] Biological components including (but not limiting to) mesenchymal stem cells (MSCs) derived from various tissues such as bone marrow, 18 adipose tissue, 37 umbilical cord, 32 muscle, 38 skin, 39 tooth, 40 and osteoblasts from different regions [41][42][43] and also several biomolecules and growth factors like bone morphogenetic protein (BMP), 37 basic fibroblast growth factor (bFGF), 41 and vascular endothelial growth factor (VEGF) 44 can be used in combination with fibrin. Different properties of these adjacent materials led to different results both in vitro and in vivo.…”

A biodegradable scaffold for the treatment of a diaphyseal bone defect of the tibia

“…The latter was also seen in the empty group, although values were not significantly different from either autograft or scaffold groups, indicating that our sample size would have to be increased to enhance the power of these results. Others have reported on neo-vasculature within porous hydroxyapatite and processed bovine cancellous bone scaffolds in murine models; however, these authors used either human endothelial cells 40 or insertion of a vascular pedicle 41 to help induce angiogenesis within these scaffolds. Angiogenesis in our study may have proceeded from pericytes within the muscle surrounding the tibial defect, the periosteum of the tibia, or the bone at the osteotomy sites.…”

Post-Transcriptional Regulation of Osteoblastic Platelet-Derived Growth Factor Receptor-Alpha Expression by Co-Cultured Primary Endothelial Cells

“…Primary endothelial cells can also be used for the generation of composite grafts for the rapid creation of functional microvessels in engineered tissues. In this context, endothelial cells were used in combination with primary osteoblasts to enhance neovascularization in bone tissue engineering applications [Rouwkema et al, 2006;Fuchs et al, 2007;Steffens et al, 2008;Yu et al, 2008]. In bone composite grafts, coimplanted endothelial cells not only support neovascularization but may also support osteogenic differentiation and osteoblastic cell functions.…”