(622m) Vascular Differentiation from Embryonic Stem Cells in 3-D Auxetic Scaffolds

Auxetic scaffolds, i.e. scaffolds that can display negative Poisson’s ratio, have unique physical properties and can expand transversally when axially strained.  Auxetic materials have been used for bioprostheses and artery stents due to the enhanced compressive strength and shear stiffness.  In tissue engineering, auxetic scaffolds could match both the elastic stiffness and the Poisson's ratio of the target tissue to better resemble native tissues and promote tissue generation.  However, the influence of auxetic materials on the cellular fate decision in the local environment is unclear.  In this study, auxetic polyurethane foams were fabricated and used to support cardiovascular differentiation from embryonic stem cells (ESCs).  The scaffolds before and after auxetic conversion were compared.  Mesoderm differentiation was induced with bone morphogenetic protein (BMP) 4 on the seeded ESCs.  The expression of alkaline phosphatase (ALP), Oct-4 and Nanog were lower after four days of differentiation for the cells grown in auxetic scaffolds.  Higher expression of vascular markers CD31 and VE-cadherin was observed for the cells from auxetic scaffolds compared to those from the scaffolds before auxetic conversion.  Little influence on the expression of cardiac marker α-actinin was observed.  The vascular cells secreted extracellular matrix (ECM) proteins vitronectin and laminin along the differentiation and expressed membrane-bound matrix metallopeptidase 9 (MMP-9), the enzyme that was involved in ECM remodeling.  The examination of Yes-associated protein (YAP) expression indicated more cytoplasmic retention in the cells from auxetic scaffolds compared to those from regular scaffolds, suggesting that the auxetic scaffolds may affect the cellular organization and contraction.  This study demonstrates a novel 3-D system that cellularizes auxetic scaffolds for vascular differentiation and provides a platform to study the influence of biophysical microenvironments on cellular differentiation from pluripotent stem cells.  The outcome of this study has implications in regenerative medicine and drug discovery.