Biohybrid elastin-like venous valve with potential for in situ tissue engineering

Figures

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  FIGURE 1. Biohybrid EVV fabrication and mechanical characterization by equibiaxial tensile testing. (A) (I) Wrap-knitted tubular textile and (ii) biohybrid scaffold (wrap-knitted tubular textile embedded with ELR hydrogel). Scale bar = 5 mm for (i) and (ii), and 500 µm for the small inserts. (B) Bileaflet EVV obtained by suturing the biohybrid tubular construct into the magnesium stent. Scale bar = 5 mm for left pictures and 4 mm for right pictures. (C) Representative stress-strain curves for the EVV tested in the circumferential and radial directions. (D) Peak tangent moduli measured between one and 1.5 MPa of stress, represented as mean ± SD (**) p < 0.001.

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  FIGURE 2. Hydrodynamic testing of the EVV in the pulse duplicator system. (A,B) Representative images of the EVV in its open and close state. Scale bar = 5 mm (C) Pressure-flow profiles for the EVV tested at peak column pressure of 60 mmHg and peak flow rates of 1,500 ml/min. (D) Regurgitation without closing volume, EOA (%), and open-valve pressure drop were tested at different pressure and flow rates.

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  FIGURE 3. Washout testing of the EVV. Representative images of the EVV at the ink-injection time, after 3 s and after complete wash-out (8 s). The test was performed at a peak pulsatile flow rate of 1,500 ml/min and a peak pressure of 60 mmHg.

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  FIGURE 4. Hemocompatibility assessment. Representative SEM images of (A,B) EVV, (C,D) GORE-TEX® and (E,F) fibrin after platelet adhesion study. (B), (D) and (F) show zoom-in SEM images of EVV, GORE-TEX® and fibrin respectively. Herein, the fully activated platelets with “fried egg” morphology were colored in green, the mild activated and non-activated platelets with extended pseudopodia or round morphology were colored in salmon, and the material surfaces were colored in blue. Scale bar = 5 µm. (G) Percentage of platelet covered area, represented as mean ± SD. (H) Percentage of hemolysis and comparison with GORE-TEX®, fibrin, and negative and positive controls, represented as mean ± SD. (*) p < 0.05 and (**) p < 0.001.

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  FIGURE 5. In vitro endothelialization study. (A) and (B) close-up images of the textile embedded with ELRs. (C) and (D) Representative confocal images of the EVV after 1 day of culture with HUVECs and subsequent immunostaining for CD31 and counterstaining with DAPI. Scale bar = 100 µm for (B,C), and scale bar = 20 µm for (D).

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  FIGURE 6. Representative images of the EVV in the balloon expansion transcatheter delivery. (A) EVV prior to balloon expansion, with four tantalum tubes sutured to facilitate X-ray visualization. (B) EVV upon balloon expansion. (C) Enlarged view of the EVV upon balloon expansion. Scale bar = 2.5 cm.