3D printing of an anatomically shaped bone model inspired by vascularized tubular bone structure

Establishing early blood vessel networks within newly formed bone is vital for its survival and the successful integration of engineered bone grafts in living organisms. To tackle this challenge, we designed bone scaffolds with integrated microchannels within three-dimensional (3D) tissue structures, inspired by the principles of bio-vascularization. Using 3D printing, these structures replicate the natural bone vascular network, encompassing Haversian and Volkmann's arteries, showing significant potential for regenerating large-scale bone defects. We designed and fabricated three groups of structures with microchannels oriented vertically (Model A), vertical-horizontal (Model B), and in a vertical-horizontal-radial-central arrangement (Model C). Microstructure imaging revealed that 3D printing facilitates the development of bio-inspired structures with hollow microchannels, closely mimicking the vascular network of natural bone. Mechanical testing showed compressive strengths of 51, 41, and 37 MPa for structures A, B, and C, respectively. Importantly, all microchannels remained unobstructed, facilitating the transport of a blood-like fluid within the structures. These structures supported effective co-culture of MG63 cells within the spongy region and human umbilical vein endothelial (hUVECs) along the channels, demonstrating their ability to support cellular organization and vascularization. Overall, our research offers a versatile framework for designing and evaluating innovative 3D bio-inspired scaffolds specifically engineered for vascularized bone engineering. Among designed models, model C with vertical-horizontal-radial-central arrangement stands out due to its unique features and cohesive vascular network, making it highly suitable for advanced applications in bone tissue engineering.