Volumetric Bioprinting of Complex Living‐Tissue Constructs within Seconds

Abstract

Biofabrication technologies, including stereolithography and extrusion‐based printing, are revolutionizing the creation of complex engineered tissues. The current paradigm in bioprinting relies on the additive layer‐by‐layer deposition and assembly of repetitive building blocks, typically cell‐laden hydrogel fibers or voxels, single cells, or cellular aggregates. The scalability of these additive manufacturing technologies is limited by their printing velocity, as lengthy biofabrication processes impair cell functionality. Overcoming such limitations, the volumetric bioprinting of clinically relevant sized, anatomically shaped constructs, in a time frame ranging from seconds to tens of seconds is described. An optical‐tomography‐inspired printing approach, based on visible light projection, is developed to generate cell‐laden tissue constructs with high viability (>85%) from gelatin‐based photoresponsive hydrogels. Free‐form architectures, difficult to reproduce with conventional printing, are obtained, including anatomically correct trabecular bone models with embedded angiogenic sprouts and meniscal grafts. The latter undergoes maturation in vitro as the bioprinted chondroprogenitor cells synthesize neo‐fibrocartilage matrix. Moreover, free‐floating structures are generated, as demonstrated by printing functional hydrogel‐based ball‐and‐cage fluidic valves. Volumetric bioprinting permits the creation of geometrically complex, centimeter‐scale constructs at an unprecedented printing velocity, opening new avenues for upscaling the production of hydrogel‐based constructs and for their application in tissue engineering, regenerative medicine, and soft robotics.

Rapid Photocrosslinking of Silk Hydrogels with High Cell Density and Enhanced Shape Fidelity

“…In this study, we demonstrated that the visible light‐initiated photoredox platform not only allows formation of sophisticated, ordered, and graduated constructs but also supported encapsulation of cells at high densities with long‐term survival and function following biofabrication. We believe that this system holds great potential for complex and free‐form architectures that can be obtained through further development of this photoresponsive silk bioink, especially using light‐based biofabrication technologies such as projection lithography, or even via recently developed fast tomographic volumetric bioprinting technologies . Finally, future studies will explore in vivo responses to this new hydrogel system and in particular investigate the beta‐sheet transformation and degradation mechanisms of this new class of silk hydrogel post‐implantation.…”

High-resolution tomographic volumetric additive manufacturing

“…Though such volumetric part generation potentially yields higher throughput (>10 5 mm 3 per hour) 21 than existing DLP and SLA techniques and allows processing more viscous resins (4-93 Pa s) 19,20,22 and even thermoreversible gels 21 , the smallest feature size demonstrated by multi-beam AM is currently limited to approximately 300 µm 18 .…”

Advanced Bottom‐Up Engineering of Living Architectures

“…Still, regarding in vivo implantation, a significant effort has been put toward improving living 3D modular constructs biointegration into surrounding host tissues by controlling/stimulating angiogenesis with the inclusion of morphogens or mechanical cues . This remains one of the most challenging aspects of bottom‐up tissue engineering but with the advent of sophisticated volumetric light‐based 3D biofabrication‐based approaches for generating flow‐functional multivascular networks, we anticipate that the ex vivo development of functional prevascularized modular tissue constructs will improve in the upcoming years. The scalability and speed of 3D bioprocessing techniques have been recently improved with elegant approaches for rapid printing of anatomically sized living architectures.…”

“…E) Tomography‐inspired volumetric bioprinting enables rapid fabrication of large‐scale anatomically shaped constructs in shear‐stress‐free conditions, combining unprecedented printing speed with high cell viability. Reproduced with permission . Copyright 2019, The Authors, published by Wiley‐VCH.…”

“…Notably, another important addition to the toolbox of advanced light‐enabled bioprinting has been recently disclosed. Volumetric bioprinting represents a groundbreaking technology that can materialize cell‐laden hydrogels at unprecedented speed and allows their manufacturing with innumerous complex geometrical features at high‐resolution . Inspired by the principles of computed tomography, the researchers irradiated a rotating cylinder containing photocrosslinkable bioink (i.e., GelMA), photoiniator and cells with a sequence of 2D light patterns that intersect and elicit spatially resolved 3D bioprinting at sites of multiple exposures.…”