Rhubarb Antagonizes Matrix Metalloproteinase-9-induced Vascular Endothelial Permeability

Background： Intact endothelial structure and function are critical for maintaining microcirculatory homeostasis. Dysfunction of the latter is an underlying cause of various organ pathologies. In a previous study, we showed that rhubarb, a traditional Chinese medicine, protected intestinal mucosal microvascular endothelial cells in rats with metastasizing septicemia. In this study, we investigated the effects and mechanisms of rhubarb on matrix metalloproteinase-9 （MMP9）-induced vascular endothelial （VE） permeability. Methods： Rhubarb monomers were extracted and purified by a series of chromatography approaches. The identity of these monomers was analyzed by hydrogen-1 nuclear magnetic resonance （NMR）, carbon-13 NMR, and distortionless enhancement by polarization transfer magnetic resonance spectroscopy. We established a human umbilical vein endothelial cell （HUVEC） monolayer on a Transwell insert. We measured the HUVEC permeability, proliferation, and the secretion of VE-cadherin into culture medium using fluorescein isothiocyanate-dextran assay, 3-（4,5-dimethyl-2-thiazolyl）-2,5-diphenyl-2-H-tetrazolium bromide assay, and enzyme-linked immunosorbent assay, respectively, in response to treatment with MMP9 and/or rhubarb monomers. Results： A total of 21 rhubarb monomers were extracted and identifed. MMP9 significantly increased the permeability of the HUVEC monolayer, which was significantly reduced by five individual rhubarb monomer （emodin, 3,8-dihydroxy- 1-methyl-anthraquinone-2-carboxylic acid, 1-O-caffeoyl-2-（4-hydroxyl-O-cinnamoyl）-β-D-glucose, daucosterol linoleate, and rhein） or a combination of all five monomers （1μmol/L for each monomer）. Mechanistically, the five-monomer mixture at 1 μmol/L promoted HUVEC proliferation. In addition, MMP9 stimulated the secretion of VE-cadherin into the culture medium, which was significantly inhibited by the five-monomer mixture. Conclusions： The rhubarb mixture ofemodin, 3,8-dihydroxy-l-methyl-anthraquinone-2-carboxylic acid, 1-O-caffeoyl-2-（4-hydroxyl-O -cinnamoyl）-μ-D-glucose, daucosterol linoleate, and rheim at a low concentration, antagonized the MMP9-induced HUVEC monolayer permeability by promoting HUVEC proliferation and reducing extracellular VE-cadherin concentrations.

Improving Vascular Regeneration Performance of Electrospun Poly(ε‑Caprolactone) Vascular Grafts via Synergistic Functionalization with VE‑Cadherin/VEGF

In vivo,vascular endothelial growth factor(VEGF)and vascular endothelial cadherin(VE-cadherin)co-regulate the dynamic organization of endothelial cells during vascular sprouting,balancing angiogenesis and vascular stability.In this study,a novel bioactive surface integrating human VE-cadherin-Fc and VEGF-Fc fusion proteins was innovatively developed for the modification of poly(ε-caprolactone)(PCL)small-caliber electrospun fibrous grafts(VE-cad/VEGF-PCL)to promote the regeneration of functional endothelium and improve the patency of artificial vascular grafts.These fusion proteins self-assembled on the PCL fibers through the hydrophobic binding of Fc domains,improving surface hydrophilicity while reducing the adhesion of fibrinogen.In vitro results showed that the VE-cadherin/VEGF surface upregulated the expression of endogenous VE-cadherin and synergistically activated the VE-cadherin/VEGFR2/FAK/AKT/ERK signal transduction,which facilitated the functioning of human umbilical vein endothelial cells(HUVECs).Moreover,the VE-cadherin/VEGF surface significantly enhanced cellularization and capillary formation,then subsequently accelerated the regeneration of functional endothelium and smooth muscle in the VE-cad/VEGF-PCL grafts in a rat abdominal aorta replacement model.Together,these results highlight the advantages of VE-cadherin/VEGF surface in enhancing rapid endothelialization of electrospun vascular grafts and provide new insights into the design of cross-activating biomaterials.