FIGURE 6.

Fucoidan inhibits the formation of procoagulant cell surface in response to serum of coronavirus disease 2019 (COVID-19) intensive care unit (ICU) patients. a) Schematic overview showing how to detect FX activation on primary human pulmonary microvascular endothelial cell (HPMEC) surface in response to 10% healthy control or COVID-19 serum. FXa production (nM) in b) first hour and c) second hour on HPMECs surface in the presence of 10% individual COVID-19 ICU sera (n=26) with and without fucoidan (10 µg mL⁻¹) for 24 h. d) Schematic overview showing how to detect thrombin generation on HPMECs cell surface in response to 10% healthy control or COVID-19 serum. e) Representative graph of thrombin generation assay in the presence of 10% healthy control, COVID-19 non-ICU, and COVID-19 ICU with and without fucoidan (same serum induced cell surface). f) Thrombin generation peak height (nM) measured on HPMECs surface in the presence of 10% individual COVID-19 ICU serum (n=26) with and without fucoidan (10 µg mL⁻¹) for 24 h. g) Pearson's correlation heatmap between endothelial dysfunction and glycocalyx shedding-related markers (angiopoietin-2 (ANG2), soluble thrombomodulin (sTM) and soluble syndecan-1 (sSDC1)) and coagulation assay parameters (FXa 1 h, FXa 2 h and thrombin peak height). Colours represent correlation; blue means negative correlated and red means positive correlated. Blank means no significance. Graphs represent the mean±sd and paired two-tailed t-tests were performed. *: p<0.05; ****: p<0.0001.