scholarly journals The choice of biopolymer is crucial to trigger angiogenesis with vascular endothelial growth factor releasing coatings

Author(s):  
Christiane Claaßen ◽  
Miriam Dannecker ◽  
Jana Grübel ◽  
Maria-Elli Kotzampasi ◽  
Günter E. M. Tovar ◽  
...  

AbstractBio-based coatings and release systems for pro-angiogenic growth factors are of interest to overcome insufficient vascularization and bio-integration of implants. This study compares different biopolymer-based coatings on polyethylene terephthalate (PET) membranes in terms of coating homogeneity and stability, coating thickness in the swollen state, endothelial cell adhesion, vascular endothelial growth factor (VEGF) release and pro-angiogenic properties. Coatings consisted of carbodiimide cross-linked gelatin type A (GelA), type B (GelB) or albumin (Alb), and heparin (Hep), or they consisted of radically cross-linked gelatin methacryloyl-acetyl (GM5A5) and heparin methacrylate (HepM5). We prepared films with thicknesses of 8–10 µm and found that all coatings were homogeneous after washing. All gelatin-based coatings enhanced the adhesion of primary human endothelial cells compared to the uncoated membrane. The VEGF release was tunable with the loading concentration and dependent on the isoelectric points and hydrophilicities of the biopolymers used for coating: GelA-Hep showed the highest releases, while releases were indistinguishable for GelB-Hep and Alb-Hep, and lowest for GM5A5-HepM5. Interestingly, not only the amount of VEGF released from the coatings determined whether angiogenesis was induced, but a combination of VEGF release, metabolic activity and adhesion of endothelial cells. VEGF releasing GelA-Hep and GelB-Hep coatings induced angiogenesis in a chorioallantoic membrane assay, so that these coatings should be considered for further in vivo testing.

2004 ◽  
Vol 89 (3) ◽  
pp. 1415-1422 ◽  
Author(s):  
Olin D. Liang ◽  
Thomas Korff ◽  
Jessica Eckhardt ◽  
Jasmin Rifaat ◽  
Nelli Baal ◽  
...  

Abstract The molecular coordination between angiogenesis and vascular remodeling is a critical step for the development of a functional vasculature in the placenta and the uterus during pregnancy. The oncodevelopmental albumin homolog α-fetoprotein (AFP) is mainly synthesized in the developing fetus, and its expression has been found to be associated with highly vascularized tumors in the adult. In this study, we investigated the angiogenic activity of AFP and its possible role in the fetomaternal unit. Immunohistochemical studies revealed that the AFP-binding protein(s) is expressed in blood vessels of chorionic villi from placentae of the second and the third but not of the first trimester during pregnancy. At low concentrations, AFP directly stimulates or enhances, respectively, vascular endothelial growth factor-induced proliferation and sprout formation of endothelial cells isolated from the placenta and the uterus possibly by a MAPK-dependent pathway. Furthermore, AFP enhances blood vessel formation in a chick chorioallantoic membrane assay in vivo. Interestingly, AFP has no proliferative or migratory effects on endothelial cells isolated from the umbilical vein in the absence of vascular endothelial growth factor. These data indicate that AFP may act as a specific proangiogenic factor of endothelial cells within the fetomaternal unit during advanced stages in pregnancy.


2013 ◽  
Vol 33 (suppl_1) ◽  
Author(s):  
Alon Hendel ◽  
David J Granville

Introduction The formation of unstable and leaky neovessels underlies the pathogenesis of a large number of chronic inflammatory diseases. Granzyme B (GZMB) is a serine protease that is expressed and released by a variety of immune cells and accumulates in the extracellular matrix (ECM) during chronic inflammation where it cleaves a number of ECM proteins, including fibronectin (FN). Vascular endothelial growth factor (VEGF) is a potent vascular permeabilizing agent that is sequestered in the ECM by binding FN in both normal and diseased tissue. We hypothesize that GZMB cleavage of FN will release VEGF from its extracellular stores and promote vascular permeability as a mechanism that contributes to neovessel leakage during chronic inflammation. Methods GZMB-mediated VEGF release from either FN coated wells or endogenously produce endothelial cell (EC) matrix was measured by VEGF ELISA. VEGF-release supernatants were used to treat EC and VEGF receptor 2 (VEGFR2) activation was evaluated by immunoblotting for phosphorylated VEGFR2. Evan’s blue was injected intravenously to CD1 mice followed by ear injection of either mouse GZMB, saline control, GZMB + neutralizing mouse VEGF antibody or GZMB+ IgG control (n=5 for each experimental group). Vascular leakage was evaluated by Evan’s blue dye extraction. Results GZMB effectively releases VEGF from both FN and from EC matrix, while inhibition of GZMB prevented VEGF release. GZMB-mediated VEGF release resulted in significant activation of VEGFR2 in EC monolayer signified by increased VEGFR2 phosphorylation. GZMB ear injection resulted in a significant increase in vascular permeability in vivo. Importantly, co-injection of GZMB and neutralizing mouse VEGF antibody significantly reduced vascular leakage compared to co-injection of GZMB and matching IgG control. Conclusions and Impact GZMB increases VEGF bioavailability by releasing it from the ECM leading to VEGFR2 activation and increased vascular permeability in vivo. These findings present a novel role for GZMB as a modulator of vascular response during chronic inflammation.


Blood ◽  
2000 ◽  
Vol 96 (13) ◽  
pp. 4216-4221 ◽  
Author(s):  
Henk M. W. Verheul ◽  
Anita S. Jorna ◽  
Klaas Hoekman ◽  
Henk J. Broxterman ◽  
Martijn F. B. G. Gebbink ◽  
...  

Abstract Coagulation abnormalities, including an increased platelet turnover, are frequently found in patients with cancer. Because platelets secrete angiogenic factors on activation, this study tested the hypothesis that platelets contribute to angiogenesis. Stimulation with vascular endothelial growth factor (VEGF, 25 ng/mL) of human umbilical vein endothelial cells (HUVECs) promoted adhesion of nonactivated platelets 2.5-fold. In contrast, stimulation of HUVECs with basic fibroblast growth factor (bFGF) did not promote platelet adhesion. By blocking tissue factor (TF) activity, platelet adhesion was prevented and antibodies against fibrin(ogen) and the platelet-specific integrin, αIIbβ3, inhibited platelet adhesion for 70% to 90%. These results indicate that VEGF-induced platelet adhesion to endothelial cells is dependent on activation of TF. The involvement of fibrin(ogen) and the αIIbβ3 integrin, which exposes a high-affinity binding site for fibrin(ogen) on platelet activation, indicates that these adhering platelets are activated. This was supported by the finding that the activity of thrombin, a product of TF-activated coagulation and a potent platelet activator, was required for platelet adhesion. Finally, platelets at physiologic concentrations stimulated proliferation of HUVECs, indicative of proangiogenic activity in vivo. These results support the hypothesis that platelets contribute to tumor-induced angiogenesis. In addition, they may explain the clinical observation of an increased platelet turnover in cancer patients. Platelets may also play an important role in other angiogenesis-dependent diseases in which VEGF is involved, such as diabetes and autoimmune diseases.


2001 ◽  
Vol 193 (5) ◽  
pp. 607-620 ◽  
Author(s):  
Gabriela L. Hernández ◽  
Olga V. Volpert ◽  
Miguel A. Íñiguez ◽  
Elisa Lorenzo ◽  
Sara Martínez-Martínez ◽  
...  

Cyclosporin A (CsA) is an immunosuppressive drug that inhibits the activity of transcription factors of the nuclear factor of activated T cells (NFAT) family, interfering with the induction of cytokines and other inducible genes required for the immune response. Here we show that CsA inhibits migration of primary endothelial cells and angiogenesis induced by vascular endothelial growth factor (VEGF); this effect appears to be mediated through the inhibition of cyclooxygenase (Cox)-2, the transcription of which is activated by VEGF in primary endothelial cells. Consistent with this, we show that the induction of Cox-2 gene expression by VEGF requires NFAT activation. Most important, the CsA-mediated inhibition of angiogenesis both in vitro and in vivo was comparable to the Cox-2 inhibitor NS-398, and reversed by prostaglandin E2. Furthermore, the in vivo corneal angiogenesis induced by VEGF, but not by basic fibroblast growth factor, was selectively inhibited in mice treated with CsA systemically. These findings involve NFAT in the regulation of Cox-2 in endothelial cells, point to a role for this transcription factor in angiogenesis, and may provide a novel mechanism underlying the beneficial effects of CsA in angiogenesis-related diseases such as rheumatoid arthritis and psoriasis.


2004 ◽  
Vol 52 (1) ◽  
pp. 39-52 ◽  
Author(s):  
Antonella N. Witmer ◽  
Bart C. van Blijswijk ◽  
Cornelis J.F. van Noorden ◽  
Gijs F.J.M. Vrensen ◽  
Reinier O. Schlingemann

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