Dual‐Stage Crosslinking of a Gel‐Phase Bioink Improves Cell Viability and Homogeneity for 3D Bioprinting

Abstract

Current bioinks for cell-based 3D bioprinting are not suitable for technology scale-up due to the challenges of cell sedimentation, cell membrane damage, and cell dehydration. A novel bioink hydrogel is presented with dual-stage crosslinking specifically designed to overcome these three major hurdles. This bioink enables the direct patterning of highly viable, multicell type constructs with long-term spatial fidelity.

Quantitative criteria to benchmark new and existing bio-inks for cell compatibility

“…The first component is a recombinant protein (C7) with seven repeats of a complementary peptide (C) that hetero-assembles with a proline-rich peptide (P) tethered to the second component, an alginate biopolymer [35, 36]. The 1:1 stoichiometric binding between C and P peptides results in a reversible, shear-thinning network with a relatively low modulus in the absence of calcium ions [35]. The secondary cross-linking mechanism exploits electrostatic alginate-Ca 2+ interactions.…”

“…Specifically, we benchmark these novel bio-inks against commercially available bio-inks (PEGDA and GelMA) using our three simple, quantitative assays for cell compatibility during bioprinting. While GelMA [5, 7, 37], PEGDA [28, 38], alginate [31, 39, 40], and recombinant protein hydrogels both with [35] and without alginate [36, 41] are known to have excellent, longterm cell compatibility when used as 3D biomaterials with encapsulated cells, their ability to maintain short-term cell viability and homogeneity during the printing and curing processes is relatively unknown. We find that our family of materials performs as well or better than the comparison bio-inks in these three criteria.…”

3D cell bioprinting of self-assembling peptide-based hydrogels

“…rheological) and biological properties of the hydrogel should be achieved to ensure the printing of constructs with high cell viability. For that purpose, different strategies have been proposed encompassing blending of the hydrogel material with gelatines, printing hybrid scaffolds using a thermoplastic as a structural reinforcement, photocrosslinking as a post-curing mechanism, physical crosslinking of spider silk recombinant proteins or dual stage crosslinking [10,[16][17][18][19][20]. While effective in increasing the mechanical stability of the constructs, these approaches generally require long fabrication times as well as the use of high temperatures and/or UV radiation, which can have detrimental effects on cell viability [21].…”

Progress in three-dimensional bioprinting

“…33 There are many examples of research labs building or implement ing lowcost 3D printing platforms for biomaterials research and tissueengineering applications. 11,[33][34][35][36] As outlined in the articles in this MRS Bulletin issue, materials researchers are now leveraging the accessibility of these machines to focus on innovations in bioinks, support materials, and applications.…”