3D Bioprinting of vasculature based on induced vasculogenesis

Abstract text (incl. figure legends and references)

Introduction and Aim

The in vitro generation of functional vasculature remains a major challenge. Current models use adult cells to mimic the three layers of native blood vessels. Yet, the coordinated morphogenetic events during vasculogenesis are key for vessel functionality and stability. iPSC-derived mesodermal progenitor cells (hiMPCs) remain viable and undergo vasculogenesis after extrusion; still, their patterning into defined shapes is yet to be established. Our study aims to biofabricate complex hierarchical vasculature using hiMPCs. We developed an in-gel bioprinting system to print low-viscosity bioinks into tubular constructs and mimic vasculogenesis.

Materials and Methods

An alginate-based bioink was supplemented with collagen type I (col I) to promote bioactivity, and xanthan gum (XG) to enhance microporosity. The bioink was extruded into molds and printed into tubular constructs using a XG-based in-gel approach. Cellular viability and morphogenetic capacity over time were evaluated using a viability assay and immunohistochemistry.

Results

The addition of col I improved cell viability and migration. Differentiation into vascular cell types and formation of vessel-like structures was observed after 2 weeks of culture. The addition of XG resulted in a less dense polymeric network which was hypothesized as beneficial for cell migration. While the alg+col I bioink promoted vasculogenesis and stable formation of vessel structures, the alg+XG+col I bioink promoted the formation of vessels through vacuolization.

Conclusion

In-gel bioprinting allows the production of shape defined structures using low viscosity bioinks. Stem cells are suitable for the biofabrication of mutilayered wall vascular structures; however, their morphogenetic mechanism depends on the morphology and composition of the matrix. Different matrices are currently under study to further understand these processes.