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International Journal of Bioprinting New fibrillar collagen for 3D printing and bioprinting

neutralization, cell inclusion and 3D printing and Project; Grant Agreement #952981). BioRender.com has
bioprinting procedures were optimized and tested for been used as support for some figures assembly.
reproducibility at different collagen concentrations, both
for the acid and the neutral fibrillar collagen masses. Conflict of interest
ColA has enough consistency for the production of Authors Amaia Guembe, José M. Rey, Teresa Zúñiga, Jesús
complex scaffolds with a remarkable amount of layers M. Izco and José I. Recalde declare that they work for
(up to 27) without collapsing and maintaining superior the company Viscofan, while the rest declare no conflicts
shape fidelity. The acidic environment of this collagen of interest.
mass makes it unsuitable for cell-laden bioinks, but the in
vitro cytotoxicity studies demonstrated that it would be Author contributions
possible to print the mass and neutralize it post-printing, Conceptualization: Jesús M. Izco, Jose Luis Pedraz, José I.
enabling cell seeding over the surface without jeopardizing Recalde
cell viability. Nonetheless, the most attractive aspect of 3D Data curation: Fatima Garcia-Villen, Amaia Guembe, José
bioprinting is the inclusion of cells in the bioink. Despite the M. Rey, Teresa Zúñiga, Sandra Ruiz-Alonso
remarkable performance of ColA in 3D printing, Viscofan Formal analysis: Fatima Garcia-Villen, José M. Rey, Amaia
S.A. has modified this collagen mass (ColN) to be easily Guembe, Teresa Zúñiga, Sandra Ruiz-Alonso
neutralizable before the bioprinting process, making the Funding acquisition: Jesús M. Izco, Jose Luis Pedraz
inclusion of cells safer. This manuscript presents an adequate Investigation: Fatima Garcia-Villen, José M. Rey, Amaia
and effective protocol for ColN collagen neutralization by Guembe, Teresa Zúñiga, Sandra Ruiz-Alonso
means of a biocompatible buffer (TRIS-HCl). The resulting Methodology: Jesús M. Izco, Jose Luis Pedraz, José I.
neutral collagen mass was fully characterized and mixed Recalde, Laura Saenz-del-Burgo, Fatima Garcia-Villen
with MSC-1 and L929 cells to produce scaffolds with proper Project administration: Jesús M. Izco, Jose Luis Pedraz
printability and shape fidelity.
Resources: Laura Saenz-Del-Burgo, Jesús M. Izco, José I.
In light of the obtained results, it is possible to state that Recalde, Jose Luis Pedraz
3% (w/w) and 2% (w/w) of pure neutral collagen bioinks Supervision: Laura Saenz-Del-Burgo, Jesús M. Izco, José I.
obtained from with ColN (without further ingredients) Recalde, Jose Luis Pedraz
are suitable for the production of 3D scaffolds intended Validation: Jesús M. Izco, Jose Luis Pedraz, José I. Recalde,
for tissue engineering. In fact, the pneumatic printing Laura Saenz-Del-Burgo, Amaia Guembe, José M. Rey,
conditions (50–80 kPa) seem to have no significant effect Teresa Zuñiga
on cell death, maintaining a cell viability over 90% even Writing – original draft: Fatima Garcia-Villen, Amaia
immediately right after the bioprinting process. Moreover, Guembe, José M. Rey, Teresa Zuñiga, Sandra Ruiz-
the printed scaffolds provided a stable platform for cell Alonso
growth and proliferation in static culture conditions up Writing – review & editing: Laura Saenz-Del-Burgo, Jesús
to 2 weeks. Despite the promising results obtained, these M. Izco, José I. Recalde, Jose Luis Pedraz
biomaterial inks must be evaluated under the specific
conditions of each particular application, especially when Ethics approval and consent to participate
combined with other ingredients. Not applicable.

Acknowledgments Consent for publication
None. Not applicable.

Funding Availability of data
This research was funded by Viscofan (S.A.) Centro para el Authors elect not to share data.
Desarrollo Tecnológico Industrial (CDTI) IDI-20210050
and the Basque Country Government/Eusko Jaurlaritza References
(Department of Education, University and Research,
Consolidated Groups IT907-16). Author Sandra Ruiz- 1. Souza AG, Silva IBB, Campos-Fernandez E, et al., 2018,
Alonso thanks the Basque Country Government for the Comparative assay of 2D and 3D cell culture models:
granted fellowship PRE_2021_2_0153. José M. Rey thanks Proliferation, gene expression and anticancer drug response.
the funding from the European’s Union Horizon 2020 Curr Pharm Des, 24(15):1689–1694.
research and Innovation framework program (Triankle https://doi.org/10.2174/1381612824666180404152304

Volume 9 Issue 3 (2023) 326 https://doi.org/10.18063/ijb.712