{
  "abstract": "Introduction Intracranial aneurysm (IA) development, growth and rupture is a complex, multifactorial process. Physiological wall shear stress (WSS) can provide a protective effect to endothelial cells lining cerebral arteries. In contrast, sites of disturbed flow where shear stress can be abnormally low (LWSS) or high (HWSS), and oscillating (OSS) have been associated with endothelial dysfunction and IAs. LWSS and HWSS, as well as altered flow direction at these regions alter endothelial nitric oxide synthase (eNOS) levels and junction protein expression such as vascular endothelial (VE)-cadherin. Remodelling of intercellular junctions through VE-cadherin disruption increases endothelium permeability, increasing monocyte infiltration, and predisposing the vascular wall to pathologies such as IAs. Although changes in VE-cadherin and eNOS have been observed under LWSS, HWSS, and OSS, both in vitro and in vivo, their combined effects remain poorly understood. By systemically varying WSS magnitude and direction, this study aimed to elucidate the relative contributions of shear magnitude and flow direction to eNOS expression and VE-cadherin localisation.Methods Human aortic endothelial cells (ECs) were exposed to flow conditions that differed in WSS magnitude (0.4 Pa, 1.5 Pa, and 3 Pa) and direction (steady unidirectional laminar flow or oscillatory flow) for 72 hours. Four experimental repeats were conducted. Immunofluorescence was used to assess eNOS and VE-cadherin expression and localisation across experimental groups. Flow conditions were validated through computational fluid dynamics. Statistical analysis was performed using GraphPad Prism (v10.6.1). Differences in relative intensity between groups were assessed using two-way ANOVA followed by Tukey’s multiple comparisons test. An alpha value of p < 0.05 was set to indicate statistical significance.Results Application of physiological and disturbed flow revealed changes in eNOS expression and endothelial dysfunction. eNOS expression was significantly increased in ECs exposed to physiological WSS and steady unidirectional HWSS compared with cells subjected to OSS and LWSS (p < 0.0001). Localisation of eNOS at the Golgi complex was also increased in ECs exposed to physiological WSS and steady unidirectional HWSS (p < 0.0001). Alterations in VE-cadherin expression and organisation were observed in response to flow (p < 0.0001). Exposure of ECs to disturbed flow disrupted VE-cadherin dynamics at cell-cell junctions, resulting in discontinuous VE-cadherin junctional staining. VE-cadherin expression levels decreased throughout the cell at HWSS, and the combination of HWSS with OSS caused cell loss.Conclusions Shear magnitude and direction are both important factors for EC function. Cells exposed to physiological values of shear through unidirectional, steady flows showed the highest expression of eNOS compared to all other conditions. Cells exposed to low, oscillatory shear demonstrate low eNOS, suggestive of endothelial dysfunction. They also exhibit discontinuous VE-cadherin junction expression, which could predispose the arterial wall to the development and progression of IAs through increased paracellular permeability. It has been observed here, for the first time, how WSS magnitude and direction influences VE-cadherin remodelling at cell junctions. These results highlight the complex interplay between flow and endothelial function that could contribute to IA formation, growth and rupture.",
  "authors": [
    {
      "affiliations": [
        "University of Sheffield, Sheffield, United Kingdom"
      ],
      "name": "Natalie Benson"
    },
    {
      "affiliations": [
        "University of Sheffield, Sheffield, United Kingdom"
      ],
      "name": "Alberto Marzo"
    },
    {
      "affiliations": [
        "University of Sheffield, Sheffield, United Kingdom"
      ],
      "name": "Melika Gul"
    },
    {
      "affiliations": [
        "University of Sheffield, Sheffield, United Kingdom"
      ],
      "name": "Jovana Serbanovic-Canic"
    }
  ],
  "title": "220 Combined effects of wall shear stress magnitude and oscillatory flows on endothelial dysfunction and VE-cadherin remodelling in vitro",
  "uid": "0a7b63fd-b06d-54e1-b641-00a7a1ffceee"
}