Biotecnologia e Biomateriais

Abstrato

Are there Technical/Clinical Tools to Improve the Present Vascular Access Outcome in Haemodialysis Patients?

Ezio Movilli

When native vein and artery are not available due to previous harvest, anatomical limitations, or disease progression, synthetic materials such as Dacron or ePTFE have been used with varying degrees of success. Synthetic graft materials are used with great success in larger diameter applications such as aortic or iliac reconstruction, but they have demonstrated unacceptably poor performance in most small diameter applications (below 6 mm inside diameter). The poor efficacy of small diameter synthetics is linked to short-term thrombosis, increased rate of infection, chronic inflammatory responses to the foreign materials, and compliance mismatch between the native tissue and the prosthetic material. These problems are well illustrated in A-V access grafts, where the intervention rates for synthetic grafts are three-fold higher than for native vein fistulas [1]. Attempts to improve the durability of prosthetic grafts began in the 1970s with the concept of seeding the luminal surface of the graft, considered to be thrombogenic, with endothelial cells [2]. The major technical feat overcome by extensive work in the 1980s and 1990s centered on preventing the cells from being dislodged by luminal blood flow on implantation of the graft. Strategies to overcome this problem include precoating the graft with various adhesives, pressure sodding, modification of the graft surface with RGD moieties, prolonged culture of the graft, and flow conditioning. The field of Cardiovascular Tissue Engineering has attempted to produce a clinically viable synthetic conduit by using a variety of in vitro approaches that typically combine living cells seeded into reconstituted scaffolds to create living tissue engineered blood vessels (TEBVs.