Novel structural designs of 3D-printed osteogenic graft for rapid angiogenesis

Large bone defect regeneration has always been recognized as a challenging clinical problem due to the difficulty of revascularization. Conventional treatments exhibit certain inherent disadvantages (e.g., secondary injury, immunization, and potential infections). However, three-dimensional (3D) printing technology as an emerging field can serve as an effective approach to achieve satisfactory revascularization while making up for the above limitations. A wide variety of methods can be used to facilitate blood supply during the design of a 3D-printed scaffold. Importantly, the scaffold structure lays a foundation for the entire printing object; any method to promote angiogenesis can be effective only if it is based on well-designed scaffolds. In this review, different designs related to angiogenesis are summarized by collecting the literature from recent years. The 3D-printed scaffolds are classified into four major categories and discussed in detail, from elementary porous scaffolds to the most advanced bone-like scaffolds. Finally, structural design suggestions to achieve rapid angiogenesis are proposed by analyzing the above architectures. This review can provide a reference for organizations or individual academics to achieve improved bone defect repair and regeneration using 3D printing. Graphic abstract