In the current phase of Coronavirus SARS-Cov-2 pandemic, there is mounting research evidence that COVID-19 disease has a significant effect not only on the respiratory system, but on endothelial cells causing multiple organ dysfunction and even failure in extreme cases. The study of endothelial cell function is emerging as an important area of research for the effective management of severely ill patients with COVID-19.
In this blog, we continue to explore how Cellix Venaflux Solutions can help researchers study mechanisms involved in the development of severe COVID-19 disease such as:
Severe systemic inflammation due to cytokine storm.
Endothelial Dysfunction - this blog focuses on this aspect and gives information on respective model and solution.
Microvascular Thrombosis - this was highlighted in our last blog, click here.
Image: Post-mortem lung specimen stained with haematoxylin and eosin showed thickened lung septa, including a large arterial vessel with mononuclear and neutrophilic infiltration (arrow in upper inset). The lower inset shows an immunohistochemical staining of caspase 3 on the same lung specimen; these staining patterns were consistent with apoptosis of endothelial cells and mononuclear cells observed in the haematoxylin-eosin-stained sections, [1].
Normal endothelial function refers to the ability of endothelium to adequately perform its physiological roles, such as the regulation of blood pressure and in hemostasis. Healthy endothelial cells synthesize nitric oxide (NO) by conversion of l-arginine to l-citrulline by endothelial nitric oxide synthase.
Endothelial cells produce nitric oxide mainly in response to shear stress. NO released by endothelium prevents leukocyte adhesion and migration, smooth muscle cell proliferation, platelet adhesion and aggregation, and opposes apoptosis and inflammation having an overall antiatherogenic effect. The endothelium has also important physiologic functions in regulating the entry of fluids and substances in and out of tissue and preserving the osmotic balance.
Coronavirus SARS-Cov-2 enters endothelial cells through endocytosis and is mediated by an interplay of ACE2 and the transmembrane protease serine 2 (TMPRSS-2). The viral spike (S) protein binds to the ACE2 receptor on the membrane of endothelial cells to facilitate its entry inside the endothelial cell.
When attacked by Coronavirus SARS-Cov-2, endothelial cells lose their ability to maintain normal functions: ability to regulate the entry of fluids and substances going in and out of tissues. The increased endothelial permeability makes it lose its tone, causes microvascular leaks and inflammation. Damage to endothelium triggers an increase in leukocyte adhesion and migration and procoagulant state, immunothrombosis, and organ ischaemia.
Cellix's VenaFlux solutions help researchers to model endothelial dysfunction in-vitro by recreating the physiological conditions of human blood vessels. This provides researchers with an experimental set-up to develop treatments to restore normal functions of the endothelial cell layer and reduce side effects of COVID-19.
In our model, engineered microcapillaries of the Vena8 Endothelial+ biochip can be seeded with endothelial cells of a respective organ (coronary artery endothelial cells, microvascular lung, microvascular kidney endothelial cells) and cell monolayers can be grown under the influence of continuous shear stress.
The Vena8 Endothelial+ biochip can be connected to a Kima pump which sits inside standard tissue culture incubators. This pumps culture medium through the biochip capillaries to imitate endothelial cell function under controlled shear stress. Endothelium cultures for 24-48 hours or longer, can be subjected to various treatments to induce pro-inflammatory and damaged states by treatment with media spiked with virus proteins or to inhibit the inflammation. In this way, the diseased state is easily modelled.
Following the treatment, cells can be analysed by high resolution fluorescence microscopy or harvested from the chips and analysed by FACS to determine the damage cause to endothelial cells. Furthermore researchers can quantify the pro-inflammatory state of the endothelial cells, by measuring the expression of ICAM, VCAM, E-selectin, P-selectin and vWF. The VenaFlux platform can also image and quantify the dynamics of leukocyte and platelet adhesion from whole blood to the endothelial cell layer.
Cellix VenaFlux Solutions can help find promising therapies that impact endothelial dysfunction to reduce complications in COVID-19 disease. If you're interested in learning more, contact us now for more information of how VenaFlux can aid your research.
References
A. S. Zinkernagel et al. Endothelial cell infection and endotheliitis in COVID-19. The Lancet. Published May 02, 2020. doi: https://doi.org/10.1016/S0140-6736(20)30937-5.
Pons, S., Fodil, S., Azoulay, E. et al. The vascular endothelium: the cornerstone of organ dysfunction in severe SARS-CoV-2 infection. Crit Care 24, 353 (2020). doi: https://doi.org/10.1186/s13054-020-03062-7
R. Seiça et al. Endothelial dysfunction — A major mediator of diabetic vascular disease. Biochimica et Biophysica Acta (BBA), Volume 1832, Issue 12, December 2013, Pages 2216-2231. doi: https://doi.org/10.1016/j.bbadis.2013.08.006