Use of vascular explants for ex vivo neovascularization of biomaterials

Biomaterial polymers have been proposed as scaffolds for cell assembly in vascular bioengineering. We describe here a new method for the neovascularization of polyurethane meshes from explants of rat aorta. Aortic rings embedded in collagen-permeated polyurethane meshes and cultured in medium supplemented with fetal bovine serum and vascular endothelial growth factor generated florid microvascular outgrowths that efficiently vascularized the available spaces between polyurethane fibers. The neovessels could be identified in the live cultures by phase-contrast microscopy, and in formalin-fixed preparations by the ABC peroxidase procedure, using the endothelial-specific Griffonia isolectin B4. The aortic outgrowths were successfully labeled with the intravital fluorescent dyes Calcein AM or SPDiOC(18), which are nontoxic and can be used for tracking studies. This study shows that artificial biomaterial meshes can be colonized ex vivo with histotypic microvascular networks, and provides the proof of concept for the future development of stably vascularized devices for in vivo implantation.