Abstract 2062: Engineering Extracellular Matrix Cues To Study The Progression Of Endothelial To Mesenchymal Transition

Abstract

Endothelial-mesenchymal transition (EndoMT) is a biological process in which vascular endothelial cells (ECs) acquire a mesenchymal identity that give rise to lineages like fibroblasts and smooth muscle-like cells. Pathologically, EndoMT is involved in the progression of cardiovascular diseases such as atherosclerosis, in which ECs give rise to smooth muscle-like cells within the plaque. However, there is essentially a dearth of knowledge of how the biochemical and biomechanical cues from the extracellular matrix (ECM) milieu directly influence the progression of EndoMT. To address the limited knowledge of ECM effects on EndoMT, we aim to develop a 3D tissue engineered model with independently tunable biochemical and biomechanical cues, including stiffness, stress relaxation rate and ECM composition to study EndoMT progression in 3D. Alginate hydrogels were prepared at 2% w/v final concentration and crosslinked using calcium sulfate and different concentrations. Human primary coronary artery endothelial cells (HCAECs, Lonza) were formed into spheroids and then co-encapuslated with fibroblasts in the alginate hydrogels for 7 days. EndoMT was induced by using media with no supplements such as VEGF and bFGF (that inhibit EndoMT) and using TGFb treatment. We successfully fabricated a family of alginate hydrogels with different mechanical and viscoelastic properties. HCAEC spheroids survived well in the 3D alginate hydrogel system and actively interacted with the fibroblasts in the hydrogels. Additionally, we observed viscoelasticity dependent migration of ECs from the spheroid into the alginate hydrogel and vessel like tube formation in the 3D model. Lastly, we quantified higher expression of the mesenchymal marker, SM22, in ECs in slow relaxing hydrogels, pointing towards viscoelasticity dependent progression of EndoMT. These results underscore the importance of mechanical factors such viscoelasticity in addition to stiffness in progression of diseases like atherosclerosis. Future work involves performing transcriptomics analysis to uncover the mechanism behind viscoelasticity dependent EndoMT progression.