Search

Light‐based 3D printing techniques represent powerful tools, enabling the precise fabrication of intricate objects with high resolution and control. An innovative addition to this set of printing techniques is Optical Fiber‐Assisted Printing (OFAP) introduced in this article. OFAP is a platform utilizing an LED‐coupled optical fiber (LOF) that selectively crosslinks photopolymer resins. It allows change of parameters like light intensity and LOF velocity during fabrication, facilitating the creation of structures with progressive features and multi‐material constructs layer‐by‐layer. An optimized formulation based on allyl‐modified gelatin (gelAGE) with food dyes as photoabsorbers is introduced. Additionally, a novel gelatin‐based biomaterial, alkyne‐modified gelatin (gelGPE), featuring alkyne moieties, demonstrates near‐visible light absorption thus fitting OFAP needs, paving the way for multifunctional hydrogels through thiol‐yne click chemistry. Besides 2D patterning, OFAP is transferred to embedded 3D printing within a resin bath demonstrating the proof‐of‐concept as a novel printing technology with potential applications in tissue engineering and biomimetic scaffold fabrication, offering rapid and precise freeform printing capabilities. [ABSTRACT FROM AUTHOR]

Atherosclerosis is the primary cause of cardiovascular disease, resulting in mortality, elevated healthcare costs, diminished productivity, and reduced quality of life for individuals and their communities. This is exacerbated by the limited understanding of its underlying causes and limitations in current therapeutic interventions, highlighting the need for sophisticated models of atherosclerosis. This review critically evaluates the computational and biological models of atherosclerosis, focusing on the study of hemodynamics in atherosclerotic coronary arteries. Computational models account for the geometrical complexities and hemodynamics of the blood vessels and stenoses, but they fail to capture the complex biological processes involved in atherosclerosis. Different in vitro and in vivo biological models can capture aspects of the biological complexity of healthy and stenosed vessels, but rarely mimic the human anatomy and physiological hemodynamics, and require significantly more time, cost, and resources. Therefore, emerging strategies are examined that integrate computational and biological models, and the potential of advances in imaging, biofabrication, and machine learning is explored in developing more effective models of atherosclerosis. [ABSTRACT FROM AUTHOR]

The current barrier to clinical translation of small‐caliber tissue‐engineered vascular grafts (TEVGs) is the long‐term patency upon implantation in vivo. Key contributors are thrombosis and stenosis caused by inadequate mechanical graft properties and mismatch of hemodynamic conditions. Herein, the authors report on an approach for the fabrication of a mechanically tunable bilayered composite TEVGs. Using a combination of solution electrospinning (SES) and melt electrowriting (MEW), it is shown that the mechanical properties can be tailored and the natural J‐shape of the stress–strain relationship can be recapitulated. Upon cell seeding, the luminal surface of the composite SES layers permits the formation of a confluent mature endothelium. MEW fibers provide structural support to promote stacking and orientation of MSCs in a near‐circumferential native vessel like direction. By adjusting the ratios of poly(ε‐caprolactone) and poly(ester‐urethane) during the SES process, TEVGs with a range of tunable mechanical properties can be manufactured. Notably, this hybrid approach permits modulation of the radial tensile properties of TEVGs to approximate different native vessels. Overall, a strategy for the fabrication of TEVGs with mechanical properties resembling those of native vessels which can help to accommodate long‐term patency of TEVGs at various treatment sites in future applications is demonstrated. [ABSTRACT FROM AUTHOR]

Melt electrowriting (MEW) is an additive manufacturing process that produces highly defined constructs with elements in the micrometer range. A specific configuration of MEW enables printing tubular constructs to create small‐diameter tubular structures. The small pool of processable materials poses a bottleneck for wider application in biomedicine. To alleviate this obstacle, an acrylate‐endcapped urethane‐based polymer (AUP), using a poly(ε‐caprolactone) (PCL) (molar mass: 20 000 g mol−1) (AUP PCL20k) as backbone material, is synthesized and utilized for MEW. Spectroscopic analysis confirms the successful modification of the PCL backbone with photo‐crosslinkable acrylate endgroups. Printing experiments of AUP PCL20k reveal limited printability but the photo‐crosslinking ability is preserved post‐printing. To improve printability and to tune the mechanical properties of printed constructs, the AUP‐material is blended with commercially available PCL (AUP PCL20k:PCL in ratios 80:20, 60:40, 50:50). Print fidelity improves for 60:40 and 50:50 blends. Blending enables modification of the constructs' mechanical properties to approximate the range of blood vessels for transplantation surgeries. The crosslinking‐ability of the material allows pure AUP to be manipulated post‐printing and illustrates significant differences in mechanical properties of 80:20 blends after crosslinking. An in vitro cell compatibility assay using human umbilical vein endothelial cells also demonstrates the material's non‐cytotoxicity. [ABSTRACT FROM AUTHOR]

Lung‐on‐chips (LoCs) are advanced microsystems designed to culture pulmonary cells under physiologically relevant conditions, including air–liquid interface, cell stretch, and shear stress. As the most promising preclinical models, the LoCs are aimed to reduce and ultimately replace conventional ineffective animal studies. Biomimetic and functional LoCs lead to more translational preclinical studies that effectively address unmet needs across therapeutic areas. A variety of cell‐ and scaffold‐based techniques are employed to establish biomimetic pulmonary cell models that closely resemble their in vivo counterparts, which is a challenging yet critical aspect of LoCs. Herein, the challenges encountered in biomimetic LoCs are discussed, and the future perspectives toward higher biomimicry using advanced biofabrication approaches are explored. [ABSTRACT FROM AUTHOR]

Several manufacturing technologies beneficially involve processing from the melt, including extrusion‐based printing, electrospinning, and electrohydrodynamic jetting. In this study, (AB)n segmented copolymers are tailored for melt‐processing to form physically crosslinked hydrogels after swelling. The copolymers are composed of hydrophilic poly(ethylene glycol)‐based segments and hydrophobic bisurea segments, which form physical crosslinks via hydrogen bonds. The degree of polymerization was adjusted to match the melt viscosity to the different melt‐processing techniques. Using extrusion‐based printing, a width of approximately 260 µm is printed into 3D constructs, with excellent interlayer bonding at fiber junctions, due to hydrogen bonding between the layers. For melt electrospinning, much thinner fibers in the range of about 1–15 µm are obtained and produced in a typical nonwoven morphology. With melt electrowriting, fibers are deposited in a controlled way to well‐defined 3D constructs. In this case, multiple fiber layers fuse together enabling constructs with line width in the range of 70 to 160 µm. If exposed to water the printed constructs swell and form physically crosslinked hydrogels that slowly disintegrate, which is a feature for soluble inks within biofabrication strategies. In this context, cytotoxicity tests confirm the viability of cells and thus demonstrating biocompatibility of this class of copolymers. [ABSTRACT FROM AUTHOR]