Engineering alginate as bioink for bioprinting

Abstract

Recent advances in 3D printing offer an excellent opportunity to address critical challenges faced by current tissue engineering approaches. Alginate hydrogels have been extensively utilized as bioinks for 3D bioprinting. However, most previous research has focused on native alginates with limited degradation. The application of oxidized alginates with controlled degradation in bioprinting has not been explored. Here, we prepared a collection of 30 different alginate hydrogels with varied oxidation percentages and concentrations to develop a bioink platform that can be applied to a multitude of tissue engineering applications. We systematically investigated the effects of two key material properties (i.e. viscosity and density) of alginate solutions on their printabilities to identify a suitable range of material properties of alginates to be applied to bioprinting. Further, four alginate solutions with varied biodegradability were printed with human adipose-derived stem cells (hADSCs) into lattice-structured, cell-laden hydrogels with high accuracy. Notably, these alginate-based bioinks were shown to be capable of modulating proliferation and spreading of hADSCs without affecting structure integrity of the lattice structures (except the highly degradable one) after 8 days in culture. This research lays a foundation for the development of alginate-based bioink for tissue-specific tissue engineering applications.

3D‐Bioprinted Osteoblast‐Laden Nanocomposite Hydrogel Constructs with Induced Microenvironments Promote Cell Viability, Differentiation, and Osteogenesis both In Vitro and In Vivo

“…Frequently used bio‐inks such as gelatin,5 alginate,6 gelatin/alginate,4 gelatin/alginate/chitosan,3 and poly(ethylene glycol) (PEG) dimethacrylate/gelatin7 that have been used in the fabrication of cell‐laden scaffolds have shown high biocompatibility for cell viability in bone repair. However, they lack osteogenic capability to promote cell differentiation and new bone formation in the absence of growth factors, which represents a clear limitation for their successful application.…”

Advances in bioprinted cell-laden hydrogels for skin tissue engineering

“…These studies also demonstrated the possibility to determine and to reduce the shear stresses transmitted to the cells through experimental and numerical studies [17,19,30,46,127]. To address the unique requirements of extrusion bioprinting regarding the print fidelity and biological characteristics, research efforts have been focused on the development of bioinks exhibiting appropriate rheological, mechanical and biological properties [28,32,74,82,100,152,169,174]. A multitude of crosslinking mechanisms, including thermal gelation, ionic and photocrosslinking, have also been explored to induce the in situ gelation of printed materials with the ultimate goal of improving the mechanical properties, the shape fidelity and the formation of interconnected 3D pores throughout the construct [4,28,107], which still remains a major challenge.…”

3D bioprinting technology for regenerative medicine applications

“…Biomimetic structure, suitable viscosity, gelation at ideal temperatures and high biocompatibility are some of the properties of alginate that makes it suitable for bioprinting [77][78][79][80][81] . Cell-laden 3D alginate hydrogels were prepared using inkjet printing [81] . Although this hydrogel provides biocompatibility and mechanical strength, it lacks cell recognition motifs.…”