Contributions of an Extracellular Matrix Glycoprotein to Coronary Vessel Formation

Introduction: Elucidation of the mechanisms that govern nascent coronary vessel formation is required to therapeutically regrow malformed vessels. Embryonic mice with epicardial-specific deletion of Tbx5 (Tbx5epi-/-) exhibit punctate cardiac hemorrhaging. Reln mRNA encodes the Reelin extracellular matrix glycoprotein and is reduced in embryonic Tbx5epi-/- mouse hearts. Therefore, expression of Reelin in coronary vascular endothelial cells may be critical for establishing vascular integrity. Study Objective: The goal of this study was to elucidate contributions of Reelin to endothelial cell function. Methods: We utilized human dermal microvascular endothelial cells (HDMECs) to assess contributions of Reelin to endothelial cell function. We achieved RELN gene silencing through a small interfering RNA-mediated approach that led to \u3e90% reduction in both RELN mRNA and Reelin protein expression. Control and RELN-silenced endothelial cells were then subjected to assays that examined adherence and the permeability of HDMEC monolayers grown on semi-porous membranes. Results: Our results indicate that RELN silencing alters in vitro endothelial cell adhesion and cell membrane permeability. Conclusions: We conclude that Reelin plays a critical role during coronary vessel development as it regulates the establishment of vascular integrity through regulation of cell adhesions and membrane permeability