Sanne de Bruin

189 Biotinylation of platelets for transfusion purposes: a novel method to label platelets in a closed system bioPLTs in the small aliquot volume of 50 ml led to substantial decrease of platelets quality (data not shown). This might be due to the sub-optimal storage and not to bi- otinylation itself. Therefore, for three PCs we transferred the biotinylated aliquot back to the retained fraction of the original PC and stored this PC for 7 days. BioPLT could be distinguished from the unbiotinylated platelets (Figure 6A). Both biotinylated and unbiotinylated showed minimal platelet activation, as expressed by CD62P expression (Figure 6B). We confirmed bioPLTs can be stored for 7 days using this method, all plate- let quality markers met Dutch blood bank quality standard. Figure 5. CD62P expression, of a fresh PC (day 1, panel A) and a stored PC (day 7, panel B). For each condition, left bars (-) represent the unstimulated state, right bars (+) represent CD62P expression in response to TRAP. After incubation with TRAP, all samples showed an increase in CD62P positive cells. At day 1, the number of CD62P positive cells increased in both the bioPLT 48.4%(41.7%-56.2%) and the sham 50.0%(41.7%-56.2%), as compared to control platelets 12,3%(9.5%-12.7%), p= 0.03. On day 7, more cells were CD62P positive in the bioPLT 69.60%(64.5%-70.3%) and sham 71.2%(66.4-75.7%) as compared to the control platelets: 44.6%(39.7%-50.3), p=0.03. No statistically significant difference was observed in comparing CD62P expression after incubation with TRAP in bioPLT with control (day 1: p=0.84, day 7 0.69) or sham platelets (day 1: p=0.11, day 7: 0.13). 7