Evaluation of molecular mechanisms of heparin-induced angiogenesis, in human umbilical vein endothelial cells

Heparin-Loaded Alginate Hydrogels: Characterization and Molecular Mechanisms of Their Angiogenic and Anti-Microbial Potential

Background: Chronic wounds continue to be a global concern that demands substantial resources from the healthcare system. The process of cutaneous wound healing is complex, involving inflammation, blood clotting, angiogenesis, migration and remodeling. In the present study, commercially available alginate wound dressings were loaded with heparin. The purpose of the study was to enhance the angiogenic potential of alginate wound dressings and analyze the antibacterial activity, biocompatibility and other relevant properties. We also aimed to conduct some molecular and gene expression studies to elaborate on the mechanisms through which heparin induces angiogenesis. Methods: The physical properties of the hydrogels were evaluated by Fourier transform infrared spectroscopy (FTIR). Swelling ability was measured by soaking hydrogels in the Phosphate buffer at 37 °C, and cell studies were conducted to evaluate the cytotoxicity and biocompatibility of hydrogels in NIH3T3 (fibroblasts). Real-time PCR was conducted to check the molecular mechanisms of heparin/alginate-induced angiogenesis. The physical properties of the hydrogels were evaluated by Fourier transform infrared spectroscopy (FTIR). Results: FTIR confirmed the formation of heparin-loaded alginate wound dressing and the compatibility of both heparin and alginate. Among all, 10 µg/mL concentration of heparin showed the best antibacterial activity against E. coli. The swelling was considerably increased up to 1500% within 1 h. Alamar Blue assay revealed no cytotoxic effect on NIH3T3. Heparin showed good anti-microbial properties and inhibited the growth of E. coli in zones with a diameter of 18 mm. The expression analysis suggested that heparin probably exerts its pro-angiogenetic effect through VEGF and cPGE. Conclusions: We report that heparin-loaded alginate dressings are not cytotoxic and offer increased angiogenic and anti-bacterial potential. The angiogenesis is apparently taken through the VEGF pathway.

Functional non-glutaraldehyde treated porcine pericardium for anti-coagulation, anti-calcification, and endothelial proliferation bioprosthetic heart valves

In the last decade, the number of transcatheter heart valve replacement for severe heart valve disease has increased exponentially. Although the bioprosthetic artificial heart valve (BHV) has similar fluid dynamics performance to the original heart valve compared with mechanical heart valve so that there is no need to take long-term anticoagulant drugs to prevent thromboembolism, transcatheter BHV replacement are still at risk for thrombosis during the first few months according to the clinical data. However, the use of antithrombotic drugs can also increase the risk of bleeding. Therefore, it is particularly important to improve the anticoagulant properties for the BHV itself. In this work, a kind of non-glutaraldehyde cross-linked BHV material with excellent antithrombotic ability has been prepared from carboxylated oxazolidine treated porcine pericardium (consisting of collagen, elastin and glycoprotein) with the further graft of the anticoagulant heparin sodium via hydrophilic modified chitosan. Along with the similar mechanical properties and collagen stability comparable to the glutaraldehyde cross-linked porcine pericardium (PP), these functional non-glutaraldehyde cross-linked PPs exhibit better biocompatibility, promoted endothelial proliferation and superior anti-calcification ability. More importantly, excellent anticoagulant activity can be observed in the hematological experiments in vivo and in vitro. In summary, these excellent performances make these functional non-glutaraldehyde cross-linked PPs great potentialities in the BHV applications.

Graphical abstract

Crosslinking of dialdehyde heparin: a new strategy for improving the anticoagulant properties of porcine acellular dermal matrix

The anticoagulant properties of valve materials are essential to maintain blood patency after artificial valve implantation. Porcine acellular dermal matrix (pADM) has low immunogenicity, good biocompatibility, and can reduce calcification by eliminating heterogeneous cells. However, its main component is collagen, which has strong coagulation function and poor anticoagulant activity. When used in heart valve materials, it can easily coagulate and form a life-threatening thrombus. Therefore, it is necessary to improve its anticoagulant performance. The glutaraldehyde (GA) cross-linked valves widely used clinically are easy to calcify with poor anticoagulant performance and cytotoxicity. In this study, dialdehyde heparin containing cross-linking active aldehyde groups was prepared by sodium periodate oxidation, then it was used for crosslinking with pADM to chemically modify its anticoagulant performance. Compared with GA cross-linked pADM (GA-pA), dialdehyde heparin cross-linked pADM (OL-pA) has better thermal stability and biocompatibility, especially its anticoagulant and antiplatelet adhesion were significantly improved, which can reduce the incidence of coagulation, thrombocytopenia and bleeding. In summary, dialdehyde heparin is expected to be applied to modify the anticoagulant properties of pADM and has great potential for the preparation and clinical application of anticoagulant materials such as heart valves and artificial blood vessels.