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 ( Tbx5 ^epi-/- ) exhibit punctate cardiac hemorrhaging. Reln mRNA encodes the Reelin extracellular matrix glycoprotein and is reduced in embryonic Tbx5 ^epi-/- 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 >90% 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.