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International Journal of Bioprinting Microfluidic-assisted 3D bioprinting

Microfluidic technologies have encouraged the creation fibers, which serve as building blocks for manufacturing
of innovative approaches for fiber spinning. Microfluidic functional tridimensional bioconstructs. In this
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spinning technology (MST) is an advanced method to context, research on microfluidics is expanding toward
fabricate microfibers made of biocompatible materials. tissue engineering applications, assisting the generation
The technology relies on microchannels to confine of valuable tools to bioprint functional macrotissues.
liquid material precursors and promote gelation prior to Conveying the advantages of both techniques, such hybrid
extrusion, which then occurs by forcing bioinks through strategy allows for the versatile spatiotemporal patterning
a small aperture called spinneret or nozzle. MST offers an of fibers as well as the control of multiple bioink deposition
increased level of versatility and sophistication compared for the production of sophisticated 3D structures. The
to other conventional fiber spinning techniques. 3,4 relatively large scale of microchannels diameter (in the
range of 100 µm) required to manipulate biomaterial
Biocompatible fibers can be laden with living inks—that are thick and often contain living cells—
cells, enabling cell interaction with the surrounding within microfluidic devices allows to benefit from recent
biomaterial, proliferation, and differentiation in a quasi- innovative microfabrication strategies, which provide
three-dimensional (3D) environment, superior to two- valuable alternatives to photolithography, offering higher
dimensional (2D) culture systems in terms of biomimicry. efficiency albeit in most cases lower resolution.
However, MST is limited by poor control in spatial
arrangement and a lack of macroscopic manufacturing Starting from recent approaches for microfluidic device
ability. The in vitro models obtained result in elongated fabrication, which now enable to create microdevices
entangled filaments that fall short of replicating the in a fast and convenient manner, this review will discuss
intricate 3D architecture of native tissues. how the integration of MST is transforming the tissue
engineering and regenerative medicine (TERM) field.
Nevertheless, tissue engineering, which aims to create After presenting general information about desirable
3D tissues that accurately mimic tissue functionalities for biomaterial characteristics and a theoretical model of
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regenerative medicine and disease modeling purposes, microfiber formation applicable to most MST strategies,
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has significantly benefitted from the development of MST. the latest experimental results will be discussed. An insight
As depicted in Figure 1, the strategic incorporation of into current advances both in pure fiber spinning and
microfluidic spinning systems on additive manufacturing MST coupling with 3D printing systems (conventional
machines, e.g., 3D bioprinters, fosters the fabrication 3D microfluidic bioprinting, c3DMB) is also given.
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of advanced spatially-organized in vitro models. This Close attention will be given to monolithic microfluidic
coupling via microfluidic operators, such as mixers platforms, referred to as advanced 3D microfluidic
and filters, enables to control the microarchitecture of bioprinting (a3DMB) systems.

Figure 1. Overview of the microfluidic-assisted 3D bioprinting for the development of functional 3D tissue models. Since laminar flow regime enables
fluid handling with extreme accuracy, microfluidic tools allow to perform diverse operations over the bioink, controlling the micromorphology and the
functionality of spun fibers to create more reliable in vitro tissue models.

Volume 10 Issue 1 (2024) 48 https://doi.org/10.36922/ijb.1404