Abstract
Three-dimensional (3D) bioprinting is on the cusp of permitting the direct fabrication of artificial living tissue. Multicellular building blocks (bioinks) are dispensed layer by layer and scaled for the target construct. However, only a few materials are able to fulfill the considerable requirements for suitable bioink formulation, a critical component of efficient 3D bioprinting. Alginate, a naturally occurring polysaccharide, is clearly the most commonly employed material in current bioinks. Here, we discuss the benefits and disadvantages of the use of alginate in 3D bioprinting by summarizing the most recent studies that used alginate for printing vascular tissue, bone and cartilage. In addition, other breakthroughs in the use of alginate in bioprinting are discussed, including strategies to improve its structural and degradation characteristics. In this review, we organize the available literature in order to inspire and accelerate novel alginate-based bioink formulations with enhanced properties for future applications in basic research, drug screening and regenerative medicine.
Highlights
Three-dimensional (3D) printing aims to integrate living cells in three-dimensional biomaterials. This revolutionary technology permits the automated and reproducible production of 3D functional living tissues by depositing layer-by-layer biocompatible materials with a high-precision positioning of cells. This technique permits the fabrication of 3D, scalable and precise geometries that are not offered by other strategies such as two-dimensional (2D) cell cultures or standard 3D cell cultures [1]
Alginate shows minimal cellular adhesion and slow degradation properties, which in some applications derives in poor cell proliferation and differentiation
The uses of oxidized alginate and/or sodium citrate seem to be promising strategies to accelerate the slow degradation of the alginate in regenerative medicine applications
Summary
Three-dimensional (3D) printing aims to integrate living cells in three-dimensional biomaterials. Hydrogels are mostly water by weight, but exhibit no flow in the steady-state due to a 3D cross-linked polymer network within the fluid, which gives them unique properties comparable to those of human tissues Due to their printability, different biocompatible hydrogels that support cell growth are employed for. We review the use of alginate (see Figure 1) in 3D bioprinting Due to their printability, different biocompatible hydrogels that support cell growth are employed for bioink fabrication: agarose, gelatin, hyaluronic acid, polyethylene glycol (PEG)-diacrylate and alginate, among others. Apart from its high biocompatibility, it is a low-cost marine material—normally obtained from the cell walls of brown algae—that forms hydrogel under mild conditions For these reasons, numerous materials scientists and bioengineers employ alginate as a component in the design and fabrication of bioinks.
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