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International Journal of Bioprinting 3D bioprinting for translational toxicology

transport mechanisms, MDCK cells are employed expression. Comparisons with 2D-cultured LLC-PK1 and
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to study epithelial permeability in the intestine and HEK293 cells revealed that 3D proximal tubular epithelial
kidneys, 43,44 A549 cells are used to evaluate the toxicity of cell models demonstrated biomarker profiles that more
inhaled substances and nanoparticles (NPs), while BEAS- closely resembled in vivo observations. However, the study
2B cells remain instrumental in examining the respiratory also noted a twofold decline in cell viability within 2 weeks,
toxicity of chemical agents. The advantages of 2D cell emphasizing a prevalent limitation associated with static
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cultures, including their high-throughput capability 3D culture methodologies.
and cost-effectiveness, render them ideal for large-scale
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screening and initial toxicity assessments. However, 2.3.3. Organoids and organ-on-a-chip models
their limitations, such as alterations in cell morphology The rapid advancements in materials science and biology
and functionality, insufficient barrier properties, and have driven the development of organoids and organ-on-
limited metabolic capacity, remain significant challenges a-chip technologies—two pioneering 3D culture systems
that warrant careful consideration. 46,47 Advances such that offer physiologically relevant models for toxicological
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as gene editing, co-culture techniques, and optimized research. Organoids are self-organizing, 3D cellular
culture conditions have provided partial solutions structures originating from pluripotent, embryonic,
to these inherent limitations. For example, MDCK or adult stem cells. These structures recapitulate the
cells’ permeability and metabolic capabilities have functional, structural, and biological complexity of
been improved via gene transfection techniques that specific organs, offering physiologically robust in vitro
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incorporate transport proteins and metabolic enzymes. platforms for toxicological investigations. Since Sato et al.
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Similarly, Deguchi et al. leveraged human iPSCs with successfully established the first intestinal organoid in
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genome editing to generate cytochrome P450 3A4- 2009, organoid technology has evolved to include diverse
knockout iPSCs, which were subsequently differentiated organ systems, such as the stomach, lung, brain,
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into hepatocyte-like cells and intestinal epithelial-like liver, heart, and kidneys. In toxicological research,
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cells. These models have yielded critical insights into organoids offer unique advantages. For example, airway
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cytochrome P450 3A4-mediated hepatic toxicity in early- organoids exposed to microplastic fibers can simulate real-
stage drug development. world exposure conditions and developmental processes,
highlighting phenomena like organoid encapsulation of
2.3.2. Three-dimensional static models
In conventional 2D cell cultures, cells exhibit adhesion microplastics, which are not observable in conventional 2D
cell models. This capability enables organoids to provide
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patterns, spatial orientation, morphology, and polarity
that substantially differ from their physiological states more accurate and sensitive insights into the impacts of
observed in vivo. By contrast, 3D culture systems allow harmful environmental factors on human health, serving
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cells to adopt spatially organized arrangements, enabling as dependable platforms for toxicological evaluations.
the dynamic regulation of essential physiological processes Organ-on-a-chip technology, based on microfluidic
across temporal and spatial dimensions, thereby facilitating systems, represents a sophisticated platform for
the reconstitution of organ or tissue functionality. Beyond mimicking human organ functionality and drug response
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serving as mere structural scaffolds, 3D culture systems mechanisms in vitro. By precisely controlling fluid shear
are required to maintain the viability of cells, tissues, and stress, mechanical strain, and co-culture conditions,
organs by emulating physiological microenvironments, these systems reconstruct organ-specific physiological
including soluble factor signaling, electrical signal microenvironments. Notably, organ-on-a-chip devices can
transmission, and extracellular matrix-mediated simulate the functions of individual organs or integrate
mechanotransduction. 47,49 Increasingly, research highlights multiple chips to construct “body-on-a-chip” systems,
the ability of 3D cell models to reproduce in vivo-like cell facilitating explorations of inter-organ communication and
morphology, thereby underscoring their applicability in pharmacokinetic dynamics. In toxicological evaluations,
toxicological investigations. this technology holds substantial potential. For instance,
Early 3D culture approaches involved incorporating lung-on-a-chip models can reproduce the complex and
cells derived from animal tissues or immortalized human integrated organ-level responses of the lungs to bacteria and
cell lines into hydrogel matrices. For instance, Astashkina inflammatory cytokines introduced into the alveolar space.
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et al. encapsulated mouse proximal tubular epithelial cells Meanwhile, the lung model reveals that cyclic mechanical
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in hydrogel matrices, generating 3D cell models to evaluate strain exacerbates the toxicity and inflammatory response
endpoints such as cytochrome P450 activity, metabolite of the lungs to silica NPs. Additionally, multi-organ chip
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production, and kidney injury molecule-1 biomarker systems provide a comprehensive framework for assessing

Volume 11 Issue 4 (2025) 102 doi: 10.36922/IJB025210209