Speaker
Description
"Introduction: One of the most challenging and daunting task of tissue engineering is the assembly and integration of functional microvasculature systems within the biofabricated tissue equivalents. Having functional vasculature is of the utmost importance to promote the rapid integration of the host’s microvasculature with the engineered one present in the graft, thus enabling an efficient transport of nutrients/removal of wastes to/from the graft. To date, a plethora of strategies have been explored to build such vasculature networks and, in the last decade great progresses have been achieved. In particular, it has been demonstrated that one can generate a vascular network via vasculogenesis – the de novo assembly of endothelial progenitor cells into capillaries – using microfabrication approaches such as microfluidic technology, 3D co-culture models (spheroids and organoids), and biofabrication via 3D bioprinting strategies. However, these milestones are still unsatisfactory and, to date, efficient protocols for the manufacturing of vascularized artificial tissues are still missing.
Methodology: To integrate a functional microvasculature within skeletal muscle tissue, we have developed a microfluidic-assisted 3D co-axial wet-spinning strategy. This technique allows to biofabricate core-shell fibres that were deposited on a rotating drum. Such fibers were composed of alginate (shell) and fibrinogen (core, bioink). Within the bioink, we loaded skeletal muscle precursors (C2C12) and gelatin methacrylate (GelMA) microbeads coated with endothelial cells (EC-GelMA) that acted as endothelium micro-seed units. Such beads were massively produced using a millipede step-emulsification microfluidic device.
Results: Applying the correct bioinks formulations, viable vascularized constructs were obtained, and vasculature micro-seeds supported the formation of a capillary-like network Interestingly, we have noticed that by increasing the core stiffness in the constructs, the endothelial cells have been able to generate vessels with different calibers switching from larger (150 microns) to smaller (50 microns) capillaries.
Conclusions: Our results have shown that: i) 3D co-axial wet-spinning is a valuable strategy to biofabricate and integrate in vitro micro-vessels within a secondary tissue; ii) the stiffness of the matrix microenvironment plays a key role over the fate of endothelial cells influencing the size/number – i.e. architecture - of the resulting microvascular network; iii) Micro-vascular seeds are an interesting solutions for engineering microvascular network, easy to manufacture and use in combination (e.g. by simply resuspension in a bioink) with other biofabrication strategies."
20941831055
