Y11 - Artery-on-chip vasculitis model

Introduction: : Vascular inflammation is a common comorbidity of systemic inflammatory diseases such as rheumatoid arthritis and systemic lupus erythematosus. Disease modeling and therapeutic development would benefit from an organotypic model of vascular inflammation featuring primary arterial cells anatomically arranged around a perfusable lumen. We have developed a 3D printed ex-vivo arterial model representative of a medium sized artery. This model is perusable and consists of the characteristic three tissue layers found in vivo: fibroblasts, smooth muscle cells and endothelial cells. To validate the relevance of our model, we compared our ex vivo artery to native healthy arteries obtained from human donors. We introduced physiologically relevant doses of inflammatory cytokines to the printed vessel response to determine its relevance as a disease model.

Materials and

Methods: : To achieve 3 distinct layers within our model, the artery was extrusion printed using 3 nested nozzles each dispensing a separate ink to form the outer fibroblast layer (2% alginate/3% gelatin/0.5 mg/ml Col I), medial smooth muscle cell layer (2% alginate/3% gelatin/0.25 mg/ml Col IV), and sacrificial core (30% pluronic F127 +100 mM CaCl₂). Evacuating the sacrificial ink results in an inner lumen in which endothelial cells can be seeded. After fully crosslinking the bioinks, by incubation in 20mM CaCl₂ and treatment with transgultaminase, the artery was cannulated within the housing unit so that it could be perfused with media under peristaltic flow. Cytokines (TNFα, IL-6, TGFβ) chosen based on their abundance in vascular inflammation were introduced at this point to induce physiologically relevant inflammation within the artery.

Results, Conclusions, and Discussions:: Our final ex-vivo arterial model has both wall thickness and lumen diameter within the range of approximately 400 – 600 um and with a clear boundary between the adventitia and media layers. Viability does not significantly decrease in the printed artery past 21 days of culture post print (Figure 1 A,B). Within 7 days of culture, we see substantial spreading of both smooth muscle cells and fibroblasts in our bioinks as well as a confluent endothelial monolayer 7 days post seeding (Figure 1C). Additionally, vessel wall and lumen sizes do not significantly change over the course of culture and the distinction between medial and adventitial layers is maintained. This suggests good mechanical stability of our model over time.

We challenged the primary arterial cells with pro-inflammatory cytokines and found the addition of TNFα altered steady state levels of transcripts primarily relating to matrix remodeling and immune cell recruitment. Ongoing work will characterize the vessel response to additional cytokines by transcriptomic analysis and immunohistochemistry to quantify the relation to native inflamed human arteries.

Acknowledgements and/or References (Optional)::