This proposal evolves from the established 7-year collaborative experience and collective expertise of the bioengineering group at GIT and the vascular biology group at UTHSCSA on the interface between fluid mechanics and endothelial structure and function. Ultimately, we plan to develop and evaluate a small (4mm) diameter synthetic graft, which has been optimally endothelialized to confluency, and fluid-mechanically preconditioned before implantation in normo- or hyperlipidemic pigs. There are 4 major aims: First, using an operational parallel plate channel flow viscometric device, we shall determine the influence of both steady state and pulsatile shear on the growth of pig aortic endothelium (PAEC) and the growth response to ECGF on polyester mesh and Gore-Tex, a brand of expanded polytetrafluoroethylene (PTFE). After optimal culture conditions, including substrate modifications, have been established, we shall examine how preconditioning of confluent PAEC by steady or pulsatile shear modifies their ability to maintain monolayer integrity in response to elevated laminar or turbulent shear stress. In addition to determining the critical denudative shear levels, monolayer integrity is quantitated as a function of cell density and the non-endothelialized graft area. The fine structural characteristics of PAEC junctions and substrate attachment sites are defined morphometrically. A third aim examines the adherence of radiolabeled (51-Cr) platelets and blood monocytes to PAEC, and the mechanisms through which the thromo-resistant or inflammatory responses of the endothelium might be regulated, under differing modalities of shear and pre-conditioning including the EC generation of chemoattractant(s), the cytokine interleukin 1 (IL alpha, beta) and arachidonate metabolites. Based on the preceding, an optimal regimen for the preconditioning and seeding of a synthetic vascular graft will be selected. Prostheses, 5-6cm in length, will first be evaluated in an in vitro flow system. Subsequently, the patency and integrity of endothelialized (confluent) preconditioned grafts will be evaluated in vivo in normo- and hyperlipidemic pigs, using a combination of vascular casting, coupled with both light microscopic and ultrastructural morphometry.