Open Access

Manuel Marcel Sirch

• The endothelial glycocalyx is a dynamic, gel-like layer composed of glycoproteins, proteoglycans, and glycolipids that lines the luminal surface of blood vessels. It plays a vital role in vascular homeostasis, contributing to the regulation of permeability, shear stress sensing, and the selective interaction between circulating elements and the endothelial surface. Its presence and structural integrity are crucial for maintaining endothelial function, yet its role remains challenging to study due to its fragility and rapid degradation under common in vitro conditions. Human Umbilical Vein Endothelial Cells (HUVECs) were used to model the endothelial glycocalyx under three defined culture conditions: (1) dynamic flow conditions to preserve and maintain an intact glycocalyx, (2) static conditions resulting in minimal or absent glycocalyx development, and (3) a deliberately degraded glycocalyx achieved by transient interruption of flow. Under these conditions a series ofThe endothelial glycocalyx is a dynamic, gel-like layer composed of glycoproteins, proteoglycans, and glycolipids that lines the luminal surface of blood vessels. It plays a vital role in vascular homeostasis, contributing to the regulation of permeability, shear stress sensing, and the selective interaction between circulating elements and the endothelial surface. Its presence and structural integrity are crucial for maintaining endothelial function, yet its role remains challenging to study due to its fragility and rapid degradation under common in vitro conditions. Human Umbilical Vein Endothelial Cells (HUVECs) were used to model the endothelial glycocalyx under three defined culture conditions: (1) dynamic flow conditions to preserve and maintain an intact glycocalyx, (2) static conditions resulting in minimal or absent glycocalyx development, and (3) a deliberately degraded glycocalyx achieved by transient interruption of flow. Under these conditions a series of complementary experiments were conducted to evaluate the influence of the glycocalyx. These included: in vitro verification and visualization of the glycocalyx, assessment of nanoparticle uptake using 50 nm fluorescent silica particles, and measurement of small molecule diffusion using the DNA-binding dye Hoechst 33342. The interaction of lipid-based nanocarriers with the endothelial surface was investigated via the adhesion of Giant Unilamellar Vesicles (GUVs) composed of DOTAP-DMPC lipid mixtures. Furthermore, the effects of shear stress and the presence or absence of the glycocalyx on the phase state of endothelial cell membranes were explored. To extend the relevance of these findings to three-dimensional models, macromolecular diffusion studies were conducted using FITC-dextrans in a hydrogel-based blood vessel model, evaluating how the glycocalyx influences molecular transport into the underlying tissue. In addition, the role of the glycocalyx in regulating endothelial cell-cell junctions was studied by analyzing the modulation of adherens junctions under the different culture conditions.…