Interactions at the blood/material interface.

The complex interactions occurring at the blood/material interface of implanted blood-contacting biomaterials largely determine the clinical efficacy of small diameter vascular grafts. Physical characteristics of the material such as chemical composition, electrical charge, surface texture, elastic modulus, and porosity all affect many responses at the interfaces with blood, surrounding tissues, and adjacent artery. Some responses begin instantaneously (deposition of plasma proteins and platelets) while other reactions are somewhat delayed (deposition of leukocytes and monocytes, and migration of endothelial cells and smooth muscle cells). Each of these elements may become activated and release bioactive substances which further affect the behavior of the other entities in this complex and dynamic microenvironment. It is precisely these tissue reactions that regulate thrombogenicity and the development of pseudointimal hyperplasia.