Functionalization with a VEGFR2-binding antibody fragment leads to enhanced endothelialization of a cardiovascular stent in vitro and in vivo.

Rapid endothelialization of cardiovascular stents is critical to prevent major clinical complications such as restenosis. Reconstruction of the native endothelium on the stent surface can be achieved by the capture of endothelial progenitor cells (EPCs) or neighboring endothelial cells (ECs) in vivo. In this study, stainless steel cardiovascular stents were functionalized with recombinant scFv antibody fragments specific for vascular endothelial growth factor receptor-2 (VEGFR2) that is expressed on EPCs and ECs. Anti-VEGFR2 scFvs were expressed in glycosylated form in Escherichia coli and covalently attached to amine-functionalized, titania-coated steel disks and stents. ScFv-coated surfaces exhibited no detectable cytotoxicity to human ECs or erythrocytes in vitro and bound 15 times more VEGFR2-positive human umbilical vein ECs than controls after as little as 3 min. Porcine coronary arteries were successfully stented with scFv-coated stents with no adverse clinical events after 30 days. Endovascular imaging and histology revealed coverage of the anti-VEGFR2 scFv-coated stent with a cell layer after 5 days and the presence of a neointima layer with a minimum thickness of 80 µm after 30 days. Biofunctionalization of cardiovascular stents with endothelial cell-capturing antibody fragments in this manner offers promise in accelerating stent endothelialization in vivo. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:213-224, 2020.

Surface evaluation of titanium oxynitride coatings used for developing layered cardiovascular stents.

Stents are important medical devices used to increase the quality and life expectancy of patients with heart diseases and stroke, leading causes of death, worldwide. In order to minimize the risk of restenosis, different coating on bare metal stents (BMS) such as polymer coatings; titanium dioxide, titanium nitride or titanium oxynitride coatings; carbon coatings and others are used. The aim of this work was to develop novel stents coated with titanium oxynitride (TiOxNy) with optimal chemical, mechanical and biological properties having possibly good coverage rate of inner and outer stent surfaces. The improvement should be achieved by optimization and development of a magnetron sputtering deposition technology. The goal of the study is understanding of the existing potential for improvement of the deposition technology and the coating quality itself. For this study, different O2/N2 ratios, meaning 1/2, 1/5 and 1/10 (the ratios of reagent gasses are given for the values of mass flows into the chamber) has been selected. Stability in simulated body fluids, surface morphology and protein adsorption as well as preliminary cytotoxic behaviour of the samples on HUVEC cells has been analysed. SEM experiments have shown the potential in the improvement of coating-stent adhesion by all samples. TiOxNy 1:5 samples were found to have the lowest adsorption, the smoothest surface morphology and the smallest rate of salt deposition from simulated body fluids (SBFs). This kind of surface has been recommended for further optimization and application.

Assembly of protein-based hollow spheres encapsulating a therapeutic factor.

Neurotrophins, as important regulators of neural development, function, and survival, have a therapeutic potential to repair damaged neurons. However, a controlled delivery of therapeutic molecules to injured tissue remains one of the greatest challenges facing the translation of novel drug therapeutics field. This study presents the development of an innovative protein-protein delivery technology of nerve growth factor (NGF) by an electrostatically assembled protein-based (collagen) reservoir system that can be directly injected into the injury site and provide long-term release of the therapeutic. A protein-based biomimetic hollow reservoir system was fabricated using a template method. The capability of neurotrophins to localize in these reservoir systems was confirmed by confocal images of fluorescently labeled collagen and NGF. In addition, high loading efficiency of the reservoir system was proven using ELISA. By comparing release profile from microspheres with varying cross-linking, highly cross-linked collagen spheres were chosen as they have the slowest release rate. Finally, biological activity of released NGF was assessed using rat pheochromocytoma (PC12) cell line and primary rat dorsal root ganglion (DRG) cell bioassay where cell treatment with NGF-loaded reservoirs induced significant neuronal outgrowth, similar to that seen in NGF treated controls. Data presented here highlights the potential of a high capacity reservoir-growth factor technology as a promising therapeutic treatment for neuroregenerative applications and other neurodegenerative diseases.