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.

Adding Functions to Biomaterial Surfaces through Protein Incorporation.

The concept of biomaterials has evolved from one of inert mechanical supports with a long-term, biologically inactive role in the body into complex matrices that exhibit selective cell binding, promote proliferation and matrix production, and may ultimately become replaced by newly generated tissues in vivo. Functionalization of material surfaces with biomolecules is critical to their ability to evade immunorecognition, interact productively with surrounding tissues and extracellular matrix, and avoid bacterial colonization. Antibody molecules and their derived fragments are commonly immobilized on materials to mediate coating with specific cell types in fields such as stent endothelialization and drug delivery. The incorporation of growth factors into biomaterials has found application in promoting and accelerating bone formation in osteogenerative and related applications. Peptides and extracellular matrix proteins can impart biomolecule- and cell-specificities to materials while antimicrobial peptides have found roles in preventing biofilm formation on devices and implants. In this progress report, we detail developments in the use of diverse proteins and peptides to modify the surfaces of hard biomaterials in vivo and in vitro. Chemical approaches to immobilizing active biomolecules are presented, as well as platform technologies for isolation or generation of natural or synthetic molecules suitable for biomaterial functionalization.