Identification of a Pro-Angiogenic Potential and Cellular Uptake Mechanism of a LMW Highly Sulfated Fraction of Fucoidan from Ascophyllum nodosum

Abstract

Herein we investigate the structure/function relationships of fucoidans from Ascophyllum nodosum to analyze their pro-angiogenic effect and cellular uptake in native and glycosaminoglycan-free (GAG-free) human endothelial cells (HUVECs). Fucoidans are marine sulfated polysaccharides, which act as glycosaminoglycans mimetics. We hypothesized that the size and sulfation rate of fucoidans influence their ability to induce pro-angiogenic processes independently of GAGs. We collected two fractions of fucoidans, Low and Medium Molecular Weight Fucoidan (LMWF and MMWF, respectively) by size exclusion chromatography and characterized their composition (sulfate, fucose and uronic acid) by colorimetric measurement and Raman and FT-IR spectroscopy. The high affinities of fractionated fucoidans to heparin binding proteins were confirmed by Surface Plasmon Resonance. We evidenced that LMWF has a higher pro-angiogenic (2D-angiogenesis on Matrigel) and pro-migratory (Boyden chamber) potential on HUVECs, compared to MMWF. Interestingly, in a GAG-free HUVECs model, LMWF kept a pro-angiogenic potential. Finally, to evaluate the association of LMWF-induced biological effects and its cellular uptake, we analyzed by confocal microscopy the GAGs involvement in the internalization of a fluorescent LMWF. The fluorescent LMWF was mainly internalized through HUVEC clathrin-dependent endocytosis in which GAGs were partially involved. In conclusion, a better characterization of the relationships between the fucoidan structure and its pro-angiogenic potential in GAG-free endothelial cells was required to identify an adapted fucoidan to enhance vascular repair in ischemia.

Effects of Sulfated Fucans from Laminaria hyperborea Regarding VEGF Secretion, Cell Viability, and Oxidative Stress and Correlation with Molecular Weight

“…This reducing effect could be due to the direct binding of VEGF, which inhibits the activation of the VEGF receptor. The negatively charged side chains of sulfated fucans can interact with the positively charged residues of the VEGF molecule, which could explain the interference in the binding between VEGF and its receptor [27]. This corresponds to findings in the literature [28,29].…”

Evaluation of Seaweed Extracts From Laminaria and Ascophyllum nodosum spp. as Biostimulants in Zea mays L. Using a Combination of Chemical, Biochemical and Morphological Approaches

“…The bands at 1,002 cm −1 (the most intense normally observed in the spectra of aromatic compounds) and about 1,600 cm −1 are present also in the spectrum of E extract, indicating a lower presence of total aromatics/polyaromatics, as compared to F extract (Table 2 ). The E extract exhibited also very intense bands at 1,085 and at about 1,270 cm −1 (shoulder) (Synytsya et al, 2014 ; Marinval et al, 2016 ) which are typical of symmetric and asymmetric stretching of sulfate groups in fucoidans, respectively, together with the band at about 815 cm −1 , attributable to bending of primary C6-O-S (Campos-Vallette et al, 2010 ; Synytsya et al, 2014 ). These three bands were present also in the other spectra, but with a lower intensity.…”

“…Raman bands, common to both spectra, at 1,340–1,346 cm −1 were assigned to in-plane CCH, COH and OCH deformations in pyranoid rings with contribution of CH 2 wagging and CH 3 symmetric bending of galactose and fucose, respectively (Synytsya et al, 2014 ). Finally, the band at about 890 cm −1 can be generically attributed to β-glycosidic bond (Marinval et al, 2016 ) or to β-D-terminal in mannose or glucose containing carbohydrates (Yang and Zhang, 2009 ).…”

Metabolite-Targeted Analysis and Physiological Traits of Zea mays L. in Response to Application of a Leonardite-Humate and Lignosulfonate-Based Products for Their Evaluation as Potential Biostimulants

“…The peaks at 1460, 1370, and 1330 cm −1 corresponded to bending vibrations of O-CH3, CH, and aliphatic OH in lignin and cellulose, respectively [35]. The peaks at 1284 and 1082 cm −1 , together with that recorded at 815 cm −1 indicated the presence of sulfated groups [37,38]. Other bands observed in the Raman spectra were less indicative to identify the functional groups present in LS2 and LS5.…”