Abstract 14125: An in vitro Pulmonary Vascular Platform From Endothelialized Whole Lung Scaffolds

Abstract

Introduction: The development of an in vitro system is critical to studying human diseases including the novel coronavirus disease-19 (COVID-19), and is typically centered on recapitulating native physiology. In the case of the pulmonary vasculature, the endothelium is critical for establishing the fluid-tight barrier in the alveolar compartment, and displays significant phenotypic and functional heterogeneity along vascular tree. Objective: Here, we developed an experimental platform that could mimic physiological functions and cellular phenotypes of pulmonary vasculature, during homeostatic and diseased states. Methods and Results: Lymphatic low pulmonary microvascular endothelial cells (Lymph low PMECs) were isolated from Prox1-GFP rodent lungs from regions of having low amounts of lymphatic tissue. Single-cell RNA-sequencing (scRNAseq) data revealed that these cells were becoming phenotypically homogenous over several passages while losing some markers of native differentiation during passaging. Intriguingly, after culturing in decellularized lung scaffolds, the phenotype of the lymph low PMEC changed back toward native lung endothelium. Vascular barrier function was partially restored in engineered lungs repopulated with endothelium, while small capillaries with patent lumens were appreciable. To evaluate the ability of the engineered endothelium to modulate permeability in response to exogenous stimuli, lipopolysaccharide (LPS) was introduced into repopulated lungs to simulate acute lung injury. After LPS treatment, the pro-inflammatory signal was significantly increased and the vascular barrier was severely impaired in the repopulated lung. Conclusions: Taken together, these results show a novel platform that recapitulates some pulmonary microvascular functions and phenotypes at a whole organ level. This development may help pave the way for using the whole organ engineering approach to model vascular diseases.