Extracellular matrix-derived and low-cost proteins to improve polyurethane-based scaffolds for vascular grafts

Abstract

Vascular graft surgeries are often conducted in trauma cases, which has increased the demand for scaffolds with good biocompatibility profiles. Biodegradable scaffolds resembling the extracellular matrix (ECM) of blood vessels are promising vascular graft materials. In the present study, polyurethane (PU) was blended with ECM proteins collagen and elastin (Col-El) and gelatin (Gel) to produce fibrous scaffolds by using the rotary jet spinning (RJS) technique, and their effects on in vitro properties were evaluated. Morphological and structural characterization of the scaffolds was performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Micrometric fibers with nanometric rugosity were obtained. Col-El and Gel reduced the mechanical strength and increased the hydrophilicity and degradation rates of PU. No platelet adhesion or activation was observed. The addition of proteins to the PU blend increased the viability, adhesion, and proliferation of human umbilical vein endothelial cells (HUVECs). Therefore, PU-Col-El and PU-Gel scaffolds are promising biomaterials for vascular graft applications.

Figure 1

SEM images and fiber diameter distributions of PU (A, D), PU-Col-El (B, E), and PU-Gel (C, F) scaffolds.

Figure 2

Micro-CT images of PU (a), PU-Col-El (b), and PU-Gel (c) scaffolds and porosity results obtained by micro-CT and gravimetry (d).

Figure 3

3D images obtained from AFM represented by a height model (top) and simultaneously acquired height and phase models (bottom) for PU (A, D), PU-Col-El (B, E), and PU-Gel (C, F) scaffolds.

Figure 4

Dynamic contact angle measurements for the scaffolds.

Figure 5

Time profiles of (a) fluid uptake and (b) in vitro degradation of scaffolds. Statistical differences were analyzed using two-way ANOVA with a Bonferroni post-hoc test (a, b, c denotes a significant difference of p < 0.05 between scaffolds; and 1, 2, 3 indicates a significant difference of p < 0.05 between time points).

Figure 6

Representative stress vs. elongation curves of PU, PU-Col-El, and PU-Gel scaffolds.

Figure 7

(a) Platelet retention index (PRI) of the scaffolds, and platelet adhesion onto (b) PU, (c) PU-Col-El, and (d) PU-Gel scaffolds.

Figure 8

(a) Fragmented DNA, (b) cell cycle profile, and (c) proliferation index (PI) determined using flow cytometry in HUVECs treated with scaffolds. Statistical differences were analyzed using two-way ANOVA with a Bonferroni post-hoc test (a, b, c denotes a significant difference of p < 0.05 between scaffolds, while 1, 2, 3 indicates a significant difference of p < 0.05 between time points).

Figure 9

Fluorescent images of HUVECs on PU, PU-Col-El, and PU-Gel scaffolds obtained using confocal microscopy. The green color corresponds to the cytoplasm, blue to the cell nuclei, and red to the scaffold fibers (on PU-Col-El and PU-Gel scaffolds).