Fig. 1.

Comparison of the functional parameters of the platelets of COVID-19 patients and healthy donors. A, B – Typical dot-plots of CD62p (P-Selectin) vs CD42b (GPIb) of the activated platelets of healthy donor (A) and COVID-19 patient (B). C – Dynamics of the platelet size (FSC MFI), GPIb shedding (CD42 Rst/Act) and P-Selectin exposure (CD62p MFI/SD) of the typical patients from non-ICU (blue), ICU (red) and ECMO (black) units. Green highlights the region of healthy values. D – Size (FSC MFI) of the platelets of the COVID-19 patients was significantly increased compared to healthy donors independently on the patient group. E, F – GPIb shedding and relative P-Selectin exposure were significantly reduced in all patients, with the values of ECMO patients being the lowest. G–H – Typical aggregation curves upon stimulation by 5 μM of TRAP-6 (G) or 100 μg/ml Fucoidan (D). Green curves – healthy donors, blue curves – irreversible aggregation of the COVID-19 patient platelets, red curves – reversible aggregation of the COVID-19 patient platelets. I, J – Platelet aggregation upon stimulation with low doses of TRAP-6 (5 μM) or normal doses of Fucoidan (100 μg/ml) was significantly diminished in all of the patients. Grey dots on all of the box plots represent individual measurements of the patients. Blue dots on all of the plots correspond to averaged measurements of the survivors. Red dots correspond to averaged measurements of the deceased patients. Statistical significance was calculated using Mann-Whitney criteria, * corresponds to p < 0.05; ** corresponds to p < 0.01; *** correspond to p < 0.001; no marking corresponds to non-significant differences. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)