Methods for assessing scaffold vascularization in vivo

The success of tissue engineering hinges on the rapid and sufficient vascularization of the neotissue. For efficient vascular network formation within three-dimensional (3D) constructs, biomaterial scaffolds that can support survival of endothelial cells as well as formation and maturation of a capillary network in vivo are highly sought after. Here, we outline a method to biofabricate 3D porous collagen scaffolds that can support extrinsic and intrinsic vascularization using two different in vivo animal models—the mouse subcutaneous implant model (extrinsic vascularization, capillary growth within the scaffold originating from host tissues outside the scaffold) and the rat tissue engineering chamber model (intrinsic vascularization, capillary growth within the scaffold derived from a centrally positioned vascular pedicle). These in vivo vascular tissue engineering approaches hold a great promise for the generation of clinically viable vascularized constructs. Moreover, the 3D collagen scaffolds can also be employed for 3D cell culture and for in vivo delivery of growth factors and cells.