Figure 7

Microcomputed tomography (microCT) angiography of vascular response to bone injury and regeneration. (A) MicroCT image of age-matched unoperated rat femur with surrounding vasculature: the large vessels on the right-hand side are the femoral artery and vein. (B) Vascular structures and bone ends 3 weeks after creation of an 8-mm bone defect. There is a robust neovascular response to bone injury, characterized by increased branching, new vessel formation, and decreased degree of vascular anisotropy. (C) MicroCT image of a nanofiber mesh wrapped around a bone defect. Bone formation has occurred on the surface of the mesh, highlighting the mesh perforations. (D) MicroCT angiography was used to visualize radially directed vascular ingrowth from the surrounding soft tissue envelope through the nanofiber mesh perforations, illustrating the contribution of soft tissues to regenerate bone vascularization and the importance of biomaterial porosity. Owing to the overlapping attenuation of bone and the lead chromate contrast agent, separate segmentation within the same sample is not possible without extensive post-processing and image registration. Images reproduced with permission from the National Academy of Sciences [28] (frames A and B) and from Elsevier [66] (frames C and D).