4D Biofabrication of T-shaped Bifurcation for Cardiovascular Tissue Engineering (CVTE) Applications

Waseem Kitana^1,*, Indra Apsite¹, Jonas Hazur², Aldo R. Boccaccini², Leonid Ionov^1,3,*

¹ Faculty of Engineering Science, University of Bayreuth, Ludwig Thoma Straße 36A, 95447 Bayreuth, Germany

² Institute of Biomaterials, Department of Material Science and Engineering, Friedrich-Alexander-University Erlangen-Nuremberg, Cauerstr. 6, 91058 Erlangen, Germany

³ Bavarian Polymer Institute, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany

* waseem.kitana@uni-bayreuth.de

*leonid.ionov@uni-bayreuth.de

4D Biofabrication, a recently developed manufacturing technique, is a 3D biofabrication method, which involves the machine-driven production of 3D constructs that are capable of shape transformation [1] [2]. Despite the fact that current 3D biofabrication methods have shown adequate advances in the fabrication of hollow vascular-like networks, their resolution is limited for the application of cells as well as the production of tube-like structures of small diameter is still challenging [1] [3] [4]. Hence, 4D biofabrication provides the fabrication of tubular constructs, which is promising for the fabrication of blood vessel substitutes with a wide range of diameters and high resolutions [1] [5].

In this study, we introduce a biofabrication method for the fabrication of T-shaped vascular bifurcation substitutes using alginate di-aldehyde (ADA) crosslinked with gelatin (Gel). In this case, alginate provides excellent rheological properties, whereas gelatin enhances cell adhesion and growth properties [4]. As a result, the fabrication of tube-like constructs with a wide range of diameters was achieved by precisely controlling the 3D printing parameters, rheological properties, and crosslinking characteristics. Accordingly, the 3D-printed and dried T-shaped thin films showed self-actuation upon immersion in water, with a resulting tube diameter of 3 mm. Additionally, the perfusion of the structures with a water-based solution, simulating the blood flow through blood vessels, showed tight tube formation with minimal leakages at the bifurcation region.

Furthermore, human umbilical vein endothelial cells (HUVECs) were seeded on top of the T-shaped structures before actuation, showed outstanding adhesion and growth properties with average cell viability of 98 % and proliferation of 33 % at all days of incubation. The achieved tube diameters are comparable to small-diameter native blood vessels, which is still a challenge in 3D biofabrication [4]. This technique will pave the way for the fabrication of vascular grafts of different geometries produced from natural hydrogels for tunable properties.

[1] Ionov, L. (2018). 4D Biofabrication: Materials, Methods, and Applications. Advanced Healthcare Materials, 7(17), 1800412. https://doi.org/10.1002/adhm.201800412

[2] Zhou, W., Qiao, Z., Nazarzadeh Zare, E., Huang, J., Zheng, X., & Sun, X. et al. (2020). 4D-Printed Dynamic Materials in Biomedical Applications: Chemistry, Challenges, and Their Future Perspectives in the Clinical Sector. Journal Of Medicinal Chemistry, 63(15), 8003-8024. https://doi.org/10.1021/acs.jmedchem.9b02115

[3] Pashneh-Tala, S., MacNeil, S., & Claeyssens, F. (2016). The Tissue-Engineered Vascular Graft—Past, Present, and Future. Tissue Engineering Part B: Reviews, 22(1), 68-100. https://doi.org/10.1089/ten.teb.2015.0100

[4] Ruther, F., Distler, T., Boccaccini, A., & Detsch, R. (2018). Biofabrication of vessel-like structures with alginate di-aldehyde—gelatin (ADA-GEL) bioink. Journal Of Materials Science: Materials In Medicine, 30(1). https://doi.org/10.1007/s10856-018-6205-7

[5] Kirillova, A., Maxson, R., Stoychev, G., Gomillion, C., & Ionov, L. (2017). 4D Biofabrication Using Shape‐Morphing Hydrogels. Advanced Materials, 29(46), 1703443. https://doi.org/10.1002/adma.201703443