The structural phospholipid and PEGylated lipid used in the mRNA-LNP does not affect platelet activation. (A-B) Quantification of MFI (bars, left y-axis) and percentage of platelets (yellow circles, right y-axis) positive for the platelet activation marker CD62P for platelets treated with mRNA-LNP consisting of different structural phospholipids or activated with CRP-XL at 4 hours in PAS_70:30 (A) and plasma (B). (C-D) Quantification of MFI (bars, left y-axis) and percentage (circles, right y-axis) of PS exposure measured using annexin V staining in platelets treated with mRNA-LNP consisting of different structural phospholipids or activated with calcium ionophore (CaI) in PAS_70:30 (C) and plasma (D). (E-F) Quantification of MFI (bars, left y-axis) and percentage of platelets (yellow circles, right y-axis) positive for the platelet activation marker CD62P for platelets treated with mRNA-LNP consisting of different PEGylated lipids or activated with CRP-XL at 4 hours in PAS_70:30 (E) and plasma (F). In some cases, activation by CRP-XL or CaI was measured in separate bags of platelets. Platelets were transfected at a concentration of 250 × 10⁶ mL⁻¹. P values were determined by the 1-way analysis of variance. Values are reported as mean ± standard error of the mean. ∗∗∗P < .001; ∗∗∗∗P < .0001. n = 3. Ns, not significant.