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International Journal of Bioprinting 3D-bioprinted multicellular lung organoids

network. This development is critical for replicating bioinks, and the shear forces generated during droplet
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the oxygenation functions of the lungs, as the vascular ejection can potentially damage cells. In addition, the
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network facilitates efficient nutrient and oxygen delivery technique is generally limited to producing relatively thin
throughout the tissue. Additionally, EBB supports the layers of tissue.
integration of high cell densities and various biomaterials,
making it suitable for the fabrication of large and intricate 3.3. Laser-based bioprinting
structures. 80,81 It also allows for the incorporation of LBB, including laser-induced forward transfer (LIFT)
mechanical and biochemical cues within the printed and stereolithography (SLA), uses laser energy to pattern
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scaffolds. The capability to incorporate mechanical and bioinks with high precision. These methods leverage
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biochemical cues within printed scaffolds further enhances laser energy to pattern bioinks with high precision
the potential of EBB in tissue engineering applications. and resolution, making them particularly suitable for
creating complex and detailed tissue constructs. LBB
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Despite its advantages, EBB typically produces offers unparalleled control over the microarchitecture
structures with lower resolution compared to other of printed tissues, which is essential for replicating the
bioprinting techniques. The necessity for high-viscosity intricate structures of lung tissue. LIFT is a non-contact
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bioinks, which are required to maintain the structure‘s bioprinting method that uses a pulsed laser to transfer
integrity during printing, can lead to challenges such as bioink from a donor substrate to a receiver substrate.
nozzle clogging and uneven cell distribution. Moreover, The laser energy creates a focused microbubble at the
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the precision of cell placement and the fine resolution of interface of the bioink and the donor substrate, propelling
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the printed constructs are often compromised, potentially a droplet of bioink towards the receiver substrate. This
affecting the overall functionality and replicability of the technique allows for high precision in droplet placement
bioprinted tissue. and minimal damage to cells due to the gentle transfer
process. SLA is a photopolymerization-based bioprinting
3.2. Inkjet-based bioprinting technique that uses a laser to selectively cure photo-
IBB utilizes droplets of bioink ejected from a printhead crosslinkable bioinks layer by layer. This method is highly
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to build structures layer by layer. This method is known precise and can produce structures with intricate details
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for its high resolution and ability to deposit small volumes and smooth surfaces. SLA is particularly advantageous
of bioink with precise control. Also, this technique uses for fabricating scaffolds with complex geometries and
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thermal or piezoelectric actuators to generate droplets internal features that are challenging to achieve with other
of bioink, which are then ejected onto a substrate in a bioprinting methods.
controlled manner. Inkjet bioprinting is particularly
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suitable for creating detailed tissue constructs and Guillotin et al. demonstrated the use of LIFT to create
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high-throughput applications. 85 high-resolution alveolar structures. The precise control
offered by LIFT allowed for the deposition of alveolar
Researchers have utilized inkjet bioprinting to create epithelial cells in defined patterns, closely mimicking
high-resolution lung models with precise cell placement. the native architecture of lung alveoli. This approach
Kang et al. developed a 3D pulmonary fibrosis model enabled the formation of functional alveolar units with
using inkjet bioprinting. They layered endothelial cells, enhanced gas exchange capabilities. Zhu et al. utilized
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type I collagen, fibroblasts, AT1 and AT2 cells using stereolithography to print lung models with detailed
inkjet bioprinting technology. In addition, they achieved vascular networks. By carefully controlling the laser
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high precision in cell placement and tissue architecture parameters and the properties of the photo-crosslinkable
by creating microfabricated lung models with inkjet bioinks, they were able to create microvascular structures
bioprinting. They reported that this layered structure that supported perfusion and enhanced the functionality
mimics the alveolar barrier model and can easily induce of the printed lung tissue. These vascular networks are
epithelial-mesenchymal transition, which is an important essential for providing nutrients and oxygen to the cells,
pathogenic mechanism in pulmonary fibrosis, and identify thereby improving cell viability and tissue integration.
biomarker expression, allowing for quick and effective LBB offers high precision and resolution, enabling
simulation of pulmonary fibrosis therapeutics.
the creation of intricate and detailed tissue structures.
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Inkjet bioprinting offers high precision and resolution, The non-contact nature of LIFT minimizes cell damage,
making it suitable for fabricating intricate tissue structures. while the layer-by-layer approach of SLA allows for the
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It also allows for the use of low-viscosity bioinks, which fabrication of complex geometries. These techniques
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can improve cell viability and functionality. However, also support the use of photo-crosslinkable bioinks,
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the low viscosity requirement limits the range of usable which can enhance the stability and functionality of
Volume 10 Issue 6 (2024) 6 doi: 10.36922/ijb.4092