Adherence of proteins, cells, and microorganisms to the surface of venous catheters contributes to catheter occlusion, venous thrombosis, thrombotic embolism, and infections. These complications lengthen hospital stays and increase patient morbidity and mortality. Current technologies for inhibiting these complications are limited in duration of efficacy and may induce adverse side effects. To prevent complications over the life span of a device without using active drugs, we modified a catheter with the nonleaching polymeric sulfobetaine (polySB), which coordinates water molecules to the catheter surface. The modified surface effectively reduced protein, mammalian cell, and microbial attachment in vitro and in vivo. Relative to commercial catheters, polySB-modified catheters exposed to human blood in vitro had a >98% reduction in the attachment and a significant reduction in activation of platelets, lymphocytes, monocytes, and neutrophils. Additionally, the accumulation of thrombotic material on the catheter surface was reduced by >99% even after catheters were exposed to serum in vitro for 60 days. In vivo, in a highly thrombogenic canine model, device- and vessel-associated thrombus was reduced by 99%. In vitro adherence of a broad spectrum of microorganisms was reduced on both the external and the internal surfaces of polySB-modified catheters compared to unmodified catheters. When unmodified and polySB-modified catheters were exposed to the same bacterial challenge and implanted into animals, 50% less inflammation and fewer bacteria were associated with polySB-modified catheters. This nonleaching, polySB-modified catheter could have a major impact on reducing thrombosis and infection, thus improving patient health.
The treatment of diseased vasculature remains challenging, in part because of the difficulty in implanting drug-eluting devices without subjecting vessels to damaging mechanical forces. Implanting materials using adhesive forces could overcome this challenge, but materials have previously not been shown to durably adhere to intact endothelium under blood flow. Marine mussels secrete strong underwater adhesives that have been mimicked in synthetic systems. Here we develop a drug-eluting bioadhesive gel that can be locally and durably glued onto the inside surface of blood vessels. In a mouse model of atherosclerosis, inflamed plaques treated with steroid-eluting adhesive gels had reduced macrophage content and developed protective fibrous caps covering the plaque core. Treatment also lowered plasma cytokine levels and biomarkers of inflammation in the plaque. The drugeluting devices developed here provide a general strategy for implanting therapeutics in the vasculature using adhesive forces and could potentially be used to stabilize rupture-prone plaques.biomaterials | catechol | delivery | endoluminal paving
Polymers used in implantable devices, although relatively unreactive, may degrade in vivo through unknown mechanisms. For example, polyetherurethane elastomers used as cardiac pacemaker lead insulation have developed surface defects after implantation. This phenomenon, termed "environmental stress cracking," requires intimate contact between polymer and host phagocytic cells, suggesting that phagocyte-generated oxidants might be involved. Indeed, brief exposure of polyetherurethane to activated human neutrophils, hypochlorous acid, or peroxynitrite produces modifications of the polymer similar to those found in vivo. Damage to the polymer appears to arise predominantly from oxidation of the urethane-aliphatic ester and aliphatic ether groups. There are substantial increases in the solid phase surface oxygen content of samples treated with hypochlorous acid, peroxynitrite or activated human neutrophils, resembling those observed in explanted polyetherurethane. Furthermore, both explanted and hypochlorous acid-treated polyetherurethane show marked reductions in polymer molecular weight. Interestingly, hypochlorous acid and peroxynitrite appear to attack polyetherurethane at different sites. Hypochlorous acid or activated neutrophils cause decreases in the urethane-aliphatic ester stretch peak relative to the aliphatic ether stretch peak (as determined by infrared spectroscopy) whereas peroxynitrite causes selective loss of the aliphatic ether. In vivo degradation may involve both hypohalous and nitric oxide-based oxidants because, after long-term implantation, both stretch peaks are diminished. These results suggest that in vivo destruction of implanted polyetherurethane involves attack by phagocyte-derived oxidants. (J. Clin. Invest. 1993Invest. . 92:2360Invest. -2367
Vasculoprotective endothelium glycocalyx (GCX) shedding plays a critical role in vascular disease. Previous work demonstrated that GCX degradation disrupts endothelial cell (EC) gap junction connexin (Cx) proteins, likely blocking interendothelial molecular transport that maintains EC and vascular tissue homeostasis to resist disease. Here, we focused on GCX regeneration and tested the hypothesis that vasculoprotective EC function can be stimulated via replacement of GCX when it is shed. We used EC with [i] intact heparan sulfate (HS), the most abundant GCX component; [ii] degraded HS; or [iii] HS that was restored after enzyme degradation, by cellular self-recovery or artificially. Artificial HS restoration was achieved via treatment with exogenous HS, with or without the GCX regenerator and protector sphingosine 1- phosphate (S1P). In these cells we immunocytochemically examined expression of Cx isotype 43 (Cx43) at EC borders and characterized Cx-containing gap junction activity by measuring interendothelial spread of gap junction permeable Lucifer Yellow dye. With intact HS, 60% of EC borders expressed Cx43 and dye spread to 2.88 ± 0.09 neighboring cells. HS degradation decreased Cx43 expression to 30% and reduced dye spread to 1.87± 0.06 cells. Cellular self-recovery of HS restored baseline levels of Cx43 and dye transfer. Artificial HS recovery with exogenous HS partially restored Cx43 expression to 46% and yielded dye spread to only 1.03 ± 0.07 cells. Treatment with both HS and S1P, recovered HS and restored Cx43 to 56% with significant dye transfer to 3.96 ± 0.23 cells. This is the first evidence of GCX regeneration in a manner that effectively restores vasculoprotective EC communication.
A series of segmented polyurethanes (SPUs) containing various polyol soft segments was prepared and their resistance to oxidative degradation was investigated after aging in AgNO3 solution. The SPU with the polyether soft segment showed a large reduction in mechanical strength after exposure to the oxidative environment. Surface cracking was often observed for these specimens. XPS measurements revealed that scission of the ether linkage occurs upon oxidation. The oxidative resistance of SPUs containing aliphatic hydrocarbon soft segments was significantly improved over the poly(tetramethylene oxide) (PTMO) based polyurethane.
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