Novel, engineered bio-inks for 3D printing of complex, perfusable structures

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Non-technical AbstractBioprinting, printing with living cells, of three-dimensional tissue has immense future potential, but progress of this emerging technology is limited by a lack of biomaterials that have the necessary mechanical properties to be printable while also having the appropriate biochemical properties to interface with living cells. In particular, biomaterials that enable perfusion, the transport of oxygen, nutrients, and other life-sustaining components, is critically lacking. The need for perfusable structures is perhaps best demonstrated through blood vessel networks, which are required to deliver oxygen and nutrients to living tissue. Perfusable structures are critically important for many other tissues throughout the body including the lymphatic system, airways, and the gastrointestinal tract. To achieve the next generation of printed tissue, this project will develop a family of biomaterials that enable a new biofabrication strategy termed Gelation of Uniform Interfacial Diffusant in Embedded 3D Printing (GUIDE-3DP). The GUIDE-3DP materials will allow rapid fabrication of perfusable networks of interconnected channels with precise control over their shapes and sizes. In Aim 1, fluid-perfusable structures with complex branch points, such as mimics of branched blood vessels will be printed. In Aim 2, materials for gas-perfusable structures will be developed. As a case study, a human intestinal tissue will be printed and evaluated for the transport of oxygen through the printed living material. In Aim 3, materials that enable fabrication of continuous vessels with precise variation of the internal diameters will be developed. As case studies, printed models of (1) vascular stenosis (in which a region of the blood vessel is constricted) and (2) the large intestine (which has a repetitive, pouch-like structure) will be printed. These biomaterials will enable the future fabrication of living tissue mimics for a variety of applications that advance, biomaterials, biotechnology, national health and will further position the US to have global leadership in the emerging field of biomanufacturing. Technical AbstractPerfusion, and specifically perfusion-enabling biomaterials, remains one of the most critical challenges in the formation of three-dimensional (3D) multicellular structures, whether for the purposes of tissue engineering, in vitro models of organ development and disease, or fundamental studies of cell behavior. The challenge of fabricating channels with specified geometry are important for multiple tissues throughout the body, including blood vessels, lymphatics, airways, and the gastrointestinal tract. To address this challenge, this project will develop a family of biomaterials that enable a new biofabrication strategy termed Gelation of Uniform Interfacial Diffusant in Embedded 3D Printing (GUIDE-3DP). Embedded 3D printing involves the fabrication of desired structures within a support material, reducing deformation and buckling due to gravity and enabling the printing of complex structures. The GUIDE-3DP method builds upon this approach by developing an interfacial diffusant strategy to rapidly fabricate perfusable networks of interconnected channels with precise control over the branching geometry and vessel diameters. In Aim 1, fluid-perfusable structures with complex branch points are fabricated. As a biological case study, endothelial cell morphology and phenotype in the bioprinted branch structures will be characterized, with a focus on how matrix mechanics alters cellular response to fluid shear stress. In Aim 2, gas-perfusable structures for controlled oxygen concentration will be fabricated. As a case study, a 3D human intestinal organoid culture model will be printed and evaluated for the role of oxygenation in regulating intestinal stem cell fate. In Aim 3, continuous vessels with precise variation of luminal diameters will be fabricated, as this geometry commonly occurs in many structures in vivo. As case studies, in vitro models of (1) vascular stenosis (in which a region of the blood vessel is constricted), and (2) the large intestine (which has a repetitive, pouch-like structure) will be printed.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.