Endothelial To Mesenchymal Transition Frequency Increases In Williams Syndrome Pulmonary Artery Endothelial Cells In Novel 3D Bioprinted In Vitro Arterial Model

Introduction: Pulmonary artery stenosis (PAS) affects 1 in 2000 live births worldwide, with several causes, most commonly by genetic mutations that lead to or are associated with other congenital heart diseases (CHD). Despite its prevalence, long-term treatment strategies for patients with PAS remains ineffective due to its heterogenous etiology. In the last few decades, researchers have found hemodynamic forces to be a great contributor to stenosis development because it induces endothelial cell (EC) dysfunction through endothelial-to-mesenchymal transition (EndMT). Current pulmonary artery models, in vivo and in vitro , are ineffective in uncovering this mechanism in PAS because they either are unable to recapitulate the phenotype or the micromechanical environment. Methods: To address these limitations, we developed and optimized a high-throughput 3D bioprinted in vitro vascular model that recapitulates patient-specific disease states to determine how EndMT plays a role in stenosis development. This bioprinted model will be a cellularized bilayer comprised of EC and smooth muscle cells (SMC) sourced from either human primary cells or our established Williams Syndrome (WS) induced-pluripotent stem cell (iPSC) lines. WS was chosen due to its high predisposition in developing PAS, around 50%. Our hypothesis is that utilizing our 3D bioprinted model, we will demonstrate how alterations in hemodynamic forces, specifically flow regiments, will further promote EndMT in the WS group. Results: Encapsulated SMC functionality and differentiated phenotype was confirmed by calcium measurement and immunohistochemistry, respectively. Single-cell RNA sequencing (scRNA-seq) was used to examine EC, SMC, EC-SMC crosstalk, and EndMT gene expression profiles. Conclusion: This work represents a new and substantive departure from conventional in vitro vascular modeling, for it will allow us to identify initial vascular cellular responses in acute non-homeostatic conditions and uncover unique signaling pathways found in multiple CHD related PAS. This fundamental knowledge from our vascular mimics can then be applied to facilitate translational advancements in treatment of PAS via surgical and transcatheter intervention methods.