New trends in vascular engineering

All cells and tissues in the organism are continually subjected to mechanical forces from various origins, ranging from a few Pascals (e.g., vascular wall shear stress) to mega-Pascals (e.g., hip cartilage) [20,54]. It is now accepted that these applied forces can modify cell and tissue behaviour by affecting metabolism, paracrine or autocrine factors, gene secretion and expression and so induce tissue remodeling. Such is the case with vascular tissue. So, from an identical genomic material, vascular cells differentiate and associate to form vessels whose composition and structural properties will be specifically adapted to their localisation and role. Adjustments occur in the course of growth or pathology, in response to hemodynamical, mechanical and/or metabolic changes [55]. Such adaptive changes may eventually be deleterious by inducing tissue remodeling, isolating cells from their surroundings and making them less sensitive to various stimulating signals. Major advances have been made in the last two years towards the understanding of these mechanisms and have led to a dynamic consideration of the arterial wall and to the advent of “vascular engineering” and the development of a new generation of vascular substitutes. After a reminder on vascular mechanics, this paper summarizes various arterial replacement alternatives.