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International Journal of Bioprinting Bioprinted tissue-on-a-chip in drug screening

bioprinting system; one was filled with the calcium To fabricate microfluidic chips, it is essential to integrate
chloride (CaCl ) solution for perfusion, and the other was a meticulously designed structure, a propulsion system,
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inoculated with two types of cells to study their interaction. a module for cell culture, and a monitoring unit.
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Compared with non-perfusion models, this construct had Fluid-driven systems are categorized into two types: (ⅰ)
a longer culture duration and better biological relevance. 101 mechanical force, such as flow micropump and pneumatic
micropump, and (ⅱ) non-mechanical force, such as gravity
Embedded bioprinting based on extrusion-based 108
bioprinting enables the construction of biocompatible and surface tension. The base materials for supporting
artificial tissues or organs, such as polydimethylsiloxane
entities without introducing heterogeneous components (PDMS) and polymethyl methacrylate (PMMA), enable
to enhance the mechanical properties. It is manifested in
two construction ways. The cell-laden bioink with poor the generation of fluid channels and the insertion of tissue
mechanical behaviors is bioprinted in a high-density cultures. PDMS, known for its inexpensive and excellent
solution (supporting bath) without biological cells to assist performance, is used in soft lithography, which is the
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in the consolidation of microarchitectures. The supporting mainstream in chip fabrication. The manufacturing
bath is replaced by culture mediums after the printed microprocesses for chips containing the pre-fabricating
constructs are gelated. The GelMA construct printed into molds, material curing, and plasma treatments are tedious.
Kapom bath had significantly improved fidelity compared to 3D bioprinting that regulates bore size and microstructure
air printing. The other case is the opposite. The sacrificial in bioprinted models may simplify the complexity of
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microfluidic chip fabrication. The combination of 3D
bioink is printed in the support bath that helps the bioink bioprinting and microfluidic technology offers certain
still during printing and maintain its structure afterward. advantages: (ⅰ) It allows for the creation of biomimetic
The latter method is beneficial for creating perfusable
microarchitectures. Embedded bioprinting breaks through structures, as common polymers like PDMS cannot culture
the traditional bottom-to-top order of model construction, cells and replicate organ or tissue microenvironments. The
thereby enabling its flexibility in printing and model use of hydrogels, popular materials in 3D bioprinting,
constructing. 103,104 Unlike coaxial bioprinting, which supports can replace PDMS and enable the culture of biomimetic
the perfusion fluid with bioprinted thin tubes, hollow tubes structures by combining these two technologies. (ⅱ)
in embedded bioprinting are perfused with the support of Automated cell seeding can be efficiently achieved on
the entire construct, reducing the risk of collapse. Embedded a large scale without requiring manual seeding. This
bioprinting also eliminates the gravity effects found in technique has the potential to construct organ or tumor
chips with complex structures. (ⅲ) Controllability can
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traditional extrusion bioprinting. However, bioprinted be achieved by manually regulating physical factors such
bioinks and supporting materials are difficult to match since as material delivery and velocity of fluid flow, thereby
support materials with non-Newtonian fluid properties
should liquify when subjected to shear stress from moving increasing experimental reproducibility.
nozzles, but present increased viscosity to support bioprinted 3D bioprinting can be applied in every step during the
bioink upon stress removal. Shao et al. developed a new fabrication of microfluidic chips, such as mold designs, cell
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strategy that combined coaxial and embedded bioprinting. inoculations, and perfusable channel manufacture that is
The endothelial cells were encapsulated in gelatin and imbued with perfusates. Colosi et al. combined these two
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adhered to the GelMA walls after the gelatin dissolved. The technologies prior to printing, thereby successfully printing
problems for nutrient distribution and metabolite removal the construct with high resolution and porosity via bioink
caused by non-perfusion were significantly represented in of lower viscosity. Two different bioinks were converged on
this research, underlining the importance of integrating a microfluidic chip into a needle for bioprinting.
perfusion into bioprinted constructs.
Interlaced vasculature and numerous substance 4. Applications: 3D-bioprinted perfusable
transport routes exist in the 3D-printed construct with models for drug screening
hierarchical grid, adding uncertainty to the experimental Mature bioink microarchitectures are constructed using
results. Although bioprinting can mimic vessels like 3D bioprinting and microfluidic technologies, which
hollow tubes with perfusable ability, it is still inefficient serve as efficient and convenient models for conducting
in dynamic culture, highlighting the need to incorporate drug screening.
microfluidic technology.
Drug screening, divided into preclinical and clinical
3.2.4. Microfluidic technology screening based on experimental types, plays an essential
The model that is fully constructed on a chip should be role in drug development. Although 3D-bioprinted
cultured for maturation under microfluidic technology. microfluidic models can express the associated growth

Volume 10 Issue 3 (2024) 183 doi: 10.36922/ijb.1951