Abstract 5555: Shear Stress Induced Activation of MAPK Pathway and GTPases of Ras and Rho Families in a Three-layered Vascular Substitute
The use of a three dimensional vascular substitute to study cell physiology is a helpful tool to understand endothelial responses when submitted to shear stress. Our group has pioneered such substitute by self-assembly, from the secretion of its own biological biomaterial, in which flow culture conditions help mimic vascular physiology. The characterization of this vascular substitute is important for clinical and research applications. In this study, we considered the cellular responses of endothelial cells in the presence of fluidic forces, and biomechanical properties of our substitute. The models were maintained in a hemodynamic bioreactor where a peristaltic pump created pulsatile flow within the lumen of the vascular model to generate shear stress and lateral pressure forces. Immunofluorescence observations revealed that endothelial cells, known to be shear stress sensors, expressed functional markers such as PECAM, VE-Cadherin and von Willebrand factor. Those observations also showed that endothelial cells aligned themselves in the direction of the flow as they do in native blood vessels. Western Blot analysis of phosphorylated MAPK (Erk, P38MAPk and JNK) and GTPases of Ras and Rho families (Rac and Rap1) indicated that endothelial cells present in our construct can trigger signalization pathways known to be involved in mechanotransduction. In the same way, results of Quantitative RT-PCR show expression of αvβ3 and α5β1 integrins, cell-matrix adhesion molecules usually found on endothelial cells. Burst pressure and other biomechanical properties were measured on specialized devices and yielded values similar to those measured on native blood vessels. This indicates a maturation of the extracellular matrix in the adventitia and media layers. Taken together, those results indicate that the endothelium is functional and that our substitute show similar characteristics to native blood vessels. Long-term functionality study is currently under progress in term of vessel replacement.