053 | Collagen-based biomaterials for biologically relevant 3D in vitro vascular models

Elena Delgrosso¹, Franca Scocozza¹, Michele Conti^1|2 | ¹Department of Civil Engineering and Architecture, University of Pavia, Italy; ²3D and Computer Simulation Laboratory, IRCCS Policlinico San Donato, San Donato Milanese [MI], Italy.

The development of biologically relevant 3D in vitro vascular models is a major goal in experimental biology and biotechnology, enabling the investigation of vascular cell behavior in controlled and reproducible environments. Among available strategies, 3D bioprinting combined with collagen-based biomaterials represents a powerful approach to recreate key structural and biological features of the vascular wall. In this study, we implemented a stepwise experimental workflow to evaluate commercially available collagen-based bioinks for the fabrication of simplified 3D vascular constructs using the FRESH (Freeform Reversible Embedding of Suspended Hydrogels) bioprinting technique. All constructs were printed as cylindrical geometries with a diameter of 10 mm and a height of 5 mm, providing a standardized and reproducible model to sequentially assess printability and maintenance of structural integrity under culture conditions. Bioinks were first screened in a cell-free setting. PureCol^® and TeloCol^® were excluded at this stage due to insufficient printability or limited maintenance of the desired geometry during incubation, whereas LifeInk^® and Fibercoll-Flex-N^® demonstrated adequate printability and long-term structural stability and were therefore advanced to biological evaluation. Selected collagen-based constructs were populated with human dermal fibroblasts (AG01522) to represent the stromal component of the vascular wall. Biological performance was assessed using Live/Dead assays performed at multiple weekly time points, starting from 24 h post-printing and extending up to 21 days of culture, revealing fibroblast viability consistently above 80% and the progressive acquisition of a characteristic elongated cell morphology, indicative of a biologically permissive microenvironment that supports cell survival and adaptation. While LifeInk^® constructs progressively softened after several weeks of culture, Fibercoll-Flex-N^® constructs preserved structural integrity for up to 21 days. Following successful biological validation, reendothelialization was investigated as a final proof-of-concept exclusively on Fibercoll-Flex-N^® constructs. Fibroblasts and human endothelial cells (HUVECs) were fluorescently labeled using CellTracker™ dyes, enabling non-destructive visualization of cell adhesion, spatial organization, and fibroblast–endothelial co-culture over time. In addition, Fibercoll-Flex-N^® constructs were successfully processed for histological sectioning, enabling hematoxylin and eosin (H&E) staining and yielding promising results in terms of spatial organization of fibroblast and endothelial components. Overall, these results demonstrate that a workflow-driven selection of collagen bioinks is essential to balance printability, durability, and biological performance in 3D bioprinted vascular models. The proposed platform provides a robust and biologically relevant in vitro system for vascular biology studies, biomaterial screening, and preclinical research. Importantly, the workflow is modular and scalable, offering a foundation for the development of more complex vascular architectures and advanced in vitro models.
This work was funded by the European Union (ERC, EPEIUS, 101125466). Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible.