In vivo performance of dual ligand augmented endothelialized expanded polytetrafluoroethylene vascular grafts

Abstract

In this study, we examined combinations of three approaches to improve the adhesion of endothelial cells (EC) onto expanded polytetrafluoroethylene (ePTFE) vascular grafts placed at the femoral artery of rats: (1) high-affinity receptor-ligand binding of RGD-streptavidin (SA) and biotin to supplement integrin-mediated EC adhesion; (2) cell sodding to pressurize the seeded EC into the interstices of the ePTFE grafts; and (3) longer postseeding attachment time from 1 to 24 h prior to implantation. An in vitro system, which accounts for cell loss due to both graft handling and shear stress, was designed to optimize conditions for in vivo experiments. Results suggest that longer in vitro attachment time enabled the adherent EC to endure mechanical stresses by forming strong adhesions to the underlying extracellular matrix substrates; cell sodding helped to retain the adherent EC by physically docking the cells against the graft interstices; and the SA-biotin interaction enhanced the early attachment of EC but did not lead to better cell retention or reduced surface coverage of blood clot in the current study. Mechanical manipulation of cells during implantation is a limiting factor in maintaining a confluent EC layer on synthetic vascular grafts.

Mylar™ and Teflon-AF™ as cell culture substrates for studying endothelial cell adhesion

“…Consequently, most EC adhesion strategies are optimized on modified glass surfaces prior to testing on vascular graft materials. As we described elsewhere [13], this is a suboptimal strategy because what works spectacularly well in vitro on glass may be of little consequence in vivo using actual vascular grafts.…”

“…It is also interesting that dual ligand treated glass yielded significantly higher values of t c compared to Mylar TM and Teflon-AF TM . The critical shear stress result with Teflon-AF TM was particularly intriguing because it may provide important insight into why dual ligand treated ePTFE 2 mm ID vascular grafts showed no advantage over FN treated grafts when tested in a rat femoral artery model [13]. The lack of difference between FN and dual ligand treatment with ePTFE in vivo was surprising because dual ligand treatment dramatically out performed FN treatment when tested in vitro on glass [37].…”

“…Additional in vitro testing showed that dual ligand treated cells exhibited enhanced expression of vasoactive agents NO and PGI 2 [12]. Despite the pronounced differences demonstrated in vitro, in vivo testing of endothelialized small diameter ePTFE grafts showed that dual ligand and FN treated grafts performed equivalently in shortterm patency testing in a rat femoral artery model [13]. Clearly, in vitro testing on modified glass was a poor predictor of the in vivo ePTFE results.…”

Adhesion and Function of Human Endothelial Cells Co-cultured on Smooth Muscle Cells

“…Human aortic ECs also remained confluent during exposure to long-term flow, as indicated by continuous PECAM staining. The orientation of the static (n = 5,9) and flow cultures (n = 4) of ECs in monoculture and ECs and SMCs in co-culture were measured (Fig. 8).…”

Poly(styrenesulfonate)/Poly(allylamine) Multilayers: A Route To Favor Endothelial Cell Growth on Expanded Poly(tetrafluoroethylene) Vascular Grafts

“…This biomimetic film type showed interesting properties in terms of blood compatibility. 24 We previously demonstrated on glass surfaces that PMFs terminated by poly(allylamine hydrochloride) (PAH) possess interesting properties in terms of initial cell adhesion and viability of ECs and that an interesting modified surface in terms of adhesion, viability, and growth concerns the PMF corresponding to poly-(ethylenimine) (PEI)-(poly(sodium 4-styrenesulfonate) (PSS)-PAH) 3 . 25 Compared to a simple PAH layer, a film architecture constituted by three PSS/PAH layer pairs was found to increase importantly the adhesion properties of ECs.…”