Speaker
Description
Anisotropy is a defining feature of many biological tissues, from skeletal muscle to vascular networks, and replicating this structural organization is crucial in the design of functional tissue constructs and relevant in vitro models. However, current biofabrication strategies often struggle to produce aligned architectures in a scalable, high-throughput, and versatile manner. Here, we present chaotic bioprinting as a robust and flexible platform for generating anisotropic hydrogel filaments with precisely aligned compartments and microchannels.
This technique leverages Kenics static mixers (KSM)—simple, helicoidal elements placed inside the printhead that split and reorient fluid streams in a deterministic and iterative manner. As materials flow through each KSM element, they are divided and folded repeatedly, creating an exponential increase in internal interfaces and generating a multilayered architecture along the filament axis. This process naturally induces structural anisotropy along the direction of extrusion, enabling the formation of constructs with aligned features at the microscale. The resolution of the internal pattern can be easily tuned by adjusting the number of KSM elements, and the resulting anisotropic microarchitecture supports a wide range of biofabrication applications.
Using this approach, we fabricated hydrogel filaments with bioactive compartments (e.g., GelMA-based inks loaded with myoblasts) flanked by materials lacking cell-adhesive motifs—such as alginate or sacrificial materials like hydroxyethyl cellulose (HEC). This configuration creates cell-instructive corridors that guide cell elongation and fusion along the fiber axis. We demonstrate that this microcompartmentalized architecture supports the formation of aligned multinucleated myotubes and promotes muscle-like tissue maturation.
Furthermore, by co-extruding cell-laden inks with fugitive materials, we generated continuous microchannels aligned along the filaments. These prevascular-like voids—up to 30 per filament and as narrow as 20 µm—significantly enhance mass transport and cell viability over extended culture. Beyond their role in oxygen and nutrient delivery, these channels provide directional guidance for cell migration and serve as a powerful platform to evaluate migratory behavior. For example, highly motile cancer cells such as MDA-MB-231 exhibit directed invasion along the channels, enabling direct visualization and quantification of migration fronts over time. In contrast, less invasive cells like MCF7 or Caco-2 display limited movement, highlighting the utility of this platform for comparative studies.
Beyond biological functionality, chaotic flows can also align functional fillers, such as one-dimensional nanomaterials (e.g., carbon nanotubes), within specific compartments. This capability opens new avenues in the development of anisotropic conductive scaffolds for electrically responsive tissues such as muscle, heart, or nerve, or for the integration of smart materials and biosensors.
Altogether, this work demonstrates that chaotic printing/bioprinting is a simple, scalable, and mathematically predictable tool to fabricate anisotropic constructs with spatially defined architectures. Its plug-and-play nature and versatility in material and cell combinations make it a valuable addition to the biofabrication toolbox for tissue engineering, disease modeling, and beyond.
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