Comparative Evaluation on Impacts of Fibronectin, Heparin-Chitosan, and Albumin Coating of Bacterial Nanocellulose Small-Diameter Vascular Grafts on Endothelialization In Vitro.

Max Wacker,Priya Veluswamy,Heike Walles,Sebastian Schürlein,Sam Varghese,Bernd Garke,Maximilian Scherner,Jan Riedel,Jörn Hülsmann,George Awad,Jens Wippermann

doi:10.3390/nano11081952

Abstract

In this study, we contrast the impacts of surface coating bacterial nanocellulose small-diameter vascular grafts (BNC-SDVGs) with human albumin, fibronectin, or heparin–chitosan upon endothelialization with human saphenous vein endothelial cells (VEC) or endothelial progenitor cells (EPC) in vitro. In one scenario, coated grafts were cut into 2D circular patches for static colonization of a defined inner surface area; in another scenario, they were mounted on a customized bioreactor and subsequently perfused for cell seeding. We evaluated the colonization by emerging metabolic activity and the preservation of endothelial functionality by water soluble tetrazolium salts (WST-1), acetylated low-density lipoprotein (AcLDL) uptake assays, and immune fluorescence staining. Uncoated BNC scaffolds served as controls. The fibronectin coating significantly promoted adhesion and growth of VECs and EPCs, while albumin only promoted adhesion of VECs, but here, the cells were functionally impaired as indicated by missing AcLDL uptake. The heparin–chitosan coating led to significantly improved adhesion of EPCs, but not VECs. In summary, both fibronectin and heparin–chitosan coatings could beneficially impact the endothelialization of BNC-SDVGs and might therefore represent promising approaches to help improve the longevity and reduce the thrombogenicity of BNC-SDVGs in the future.

Highlights

We developed an acellular tissue-engineered vascular grafts (TEVG) composed of bacterial nanocellulose (BNC) with a small inner diameter
We report the endothelialization of small-diameter vascular grafts made of BNC which were either coated with fibronectin, heparin–chitosan, or albumin in a clinically relevant in vitro setting and tried to simulate the natural and necessary stimulation by wall shear stress in a bioreactor
The heparin-coated grafts stained with toluidine blue exhibited a deep blue staining covering the whole surface, compared to uncoated grafts (Figure 2C), and the detection of sulphur (1.1% vs. 0% for uncoated or albumin-/fibronectin-coated grafts) on the luminal side by XPS analyses indicated the presence of the highly sulphated glycosaminoglycan heparin

Summary

Introduction

Coronary artery bypass grafting (CABG) is the most frequently performed heart surgeries in the western world. In Germany and the USA alone, more than 450,000 CABG operations are conducted every year, using small caliber vascular grafts with an inner diameter of 6 mm or below to redirect the blood distal to the blockage [1,2]. Are considered the gold standard for graft material in CABG surgery, as they represent the best compromise between availability and long-term patency rate, which is mainly dependent on the biological function of the grafts, e.g., the endothelial integrity and mechanical characteristics of the vessel wall [3,4]. While the optimal bypass graft has Nanomaterials 2021, 11, 1952.

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