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International Journal of Bioprinting 3D-bioprinted multicellular lung organoids

3. Bioprinting techniques for lung printed object. In contrast, bioprinting is specifically
model fabrication designed for creating biological constructs, including
tissues and organs, using bioinks composed of living cells
Additive manufacturing, also known as 3D printing, and biomaterials. 73–75 It aims to replicate the complex
involves creating components by layering materials. architecture of biological tissues, facilitating cell growth
71
Additive manufacturing systems are categorized into and function, with applications predominantly in the
seven distinct processes based on how material layers are field of medicine and biological research, such as tissue
formed: (1) material extrusion (MEX), where material engineering, regenerative medicine, and the development
is selectively dispensed through a nozzle or orifice; (2) of in vitro models for drug testing. Bioprinting technology
vat photopolymerization (VPP), which uses a vat of can be broadly categorized into three main types: extrusion-
liquid photopolymer selectively cured by light-activated based bioprinting (EBB), inkjet-based bioprinting
polymerization; (3) powder bed fusion (PBF), where (IBB), and laser-based bioprinting (LBB). These three
thermal energy selectively fuses regions of a powder bioprinting methods each have unique advantages and are
bed; (4) binder jetting (BJT), in which a liquid binder chosen based on the specific requirements of the tissue
is selectively deposited to bind powder materials; (5) engineering application (Figure 2). These technologies
material jetting (MJT), where droplets of build material are hold significant potential for advancing tissue engineering,
selectively deposited using an inkjet print head; (6) directed as it enables the creation of complex structures that closely
energy deposition (DED), which utilizes focused thermal mimic the natural architecture of biological tissues, such
energy to fuse materials by melting them as they are being as lung tissue. 76
deposited; and (7) sheet lamination (SHL), where sheets of 3.1. Extrusion-based bioprinting
material are bonded together to form a part. Among these EBB is one of the most commonly employed methods in
seven methods, those applicable to bioprinting technology the field of bioprinting due to its versatility and ability to
using living cells are MEX, VPP, and MJT. handle a broad range of biomaterials, including hydrogels,
3D printing and bioprinting, while similar in their biopolymers, and cell-laden bioinks. 19,77 This technique
layer-by-layer fabrication approach, differ significantly operates by the controlled extrusion of bioink through a
in their applications and materials used. 3D printing is nozzle, which deposits material layer by layer to construct
78
primarily used for creating non-biological objects from 3D structures. The continuous filament formation
materials such as plastics, metals, and ceramics, with under regulated pressure allows EBB to effectively create
common applications in manufacturing, prototyping, scaffolds embedded with cells, resulting in complex
75
and the creation of complex mechanical parts. It utilizes tissue constructs.
72
materials that are often rigid and non-living, focusing For instance, Miller et al. demonstrated the use of EBB to
on the structural integrity and functional aspects of the fabricate a lung model integrated with a perfusable vascular

Figure 2. Schematic of three main bioprinting techniques. The three main bioprinting techniques include extrusion-based, inkjet-based, and laser-based
„
bioprintings. This diagram was created with BioRender.com (adapted from “Types of Additive Manufacturing in Bioprinting Processes ; retrieved from
https://app.biorender.com/biorender-templates).

Volume 10 Issue 6 (2024) 5 doi: 10.36922/ijb.4092