Prosthetic vascular grafts: Wrong models, wrong questions and no healing

Human Endothelial Progenitor Cells

“…In some instances, these deposited blood cells from the circulating blood are soon replaced by migrating and spreading endogenous endothelium. In other instances, colonies of replicating endothelial cells grow on the exposed area but fail to completely repopulate the monolayer and with time these areas of exposed basement membrane develop a fibrous and nonthrombogenic covering (Berger et al 1972;Herring et al 1984;Clowes et al 1985Clowes et al , 1986Zilla et al 1994Zilla et al , 2007. Thus, the extent and type of vascular intima repair or regeneration is perhaps dependent on the extent and type of injury or implant and perhaps the age of the host.…”

The Assembly of Nonadhesive Fibrinogen Matrices Depends on the αC Regions of the Fibrinogen Molecule

“…However, numerous studies using traditional staining methods, isotopes, and electron microscopy (7)(8)(9) as well as recent studies using new imaging techniques (1,2) have not detected platelets on the surface of fibrin. Moreover, previous reports have documented that the surface of implanted vascular grafts, which is exposed to flowing blood and invariably coated with fibrin, remains acellular over the years after implantation (10). The anti-adhesive mechanisms that protect the fibrin cap of hemostatic clots and the lumenal fibrin of implanted biomaterials from the excessive accumulation of blood cells in vivo are poorly understood.…”

In Vitro Method for Real-Time, Direct Observation of Cell–Vascular Graft Interactions under Simulated Blood Flow

“…24 Spontaneous EC ingrowth or ''in situ endothelialization'' rarely occurs in humans on prosthetic grafts. 25 Therefore, a goal for tissue engineered grafts is to produce a lumenal surface that is both resistant to platelet aggregation and favorable for EC regrowth. The flow chamber allows a temporal observation of EC proliferation and morphological adaptation to SS in situ.…”