Sanne de Bruin

185 Biotinylation of platelets for transfusion purposes: a novel method to label platelets in a closed system -30º (Figure 3). Irradiation of the biotin-labeled PC with a standard dose of 25 Gray did not affect the degree of biotinylation. (Figure 3). It was not possible to incubate the platelets with biotin and add ACD-A simultaneously. (Figure 3). This would have reduced one processing step. The reduction of biotinylation after additions of ACD-A is probably due to a lower pH. Figure 2. Flow-cytometric analysis of unlabeled (blue), sham (grey) and bioPLTs (red), after incubation with streptavidin-488. The bioPLT show a significant higher fluorescent intensity as compared to the sham and control platelets. 98.4% ± 0.9% of bioPLTs were biotinylated, and can be visualized as a distinct population. Scatters of all three populations are similar (left). Images are from a selected PC, but are representative for the other experiments (n=6). Effects of the biotinylation procedure on platelet quality parameters Platelet quality parameters were assessed to assure bioPLTs met the requirements of the Dutch blood bank. Ranges for quality parameters were pre-defined and are ex- pressed in Table 1. Platelet counts, pH and ‘swirling’ score were within the range ac- cepted by the Dutch blood bank for all products. Morphology scores were higher for control platelets, as compared to sham and bioPLTs. There was no significant difference between sham and bioPLTmorphology scores, indicating that the difference to control was caused by the processing steps with repeated centrifugation steps and not by incu- bation with biotin. The procedure led to amarginal decrease in platelet count. AnnexinV binding was not affected by the procedure (Figure 4). CD62P expression was increased to the same extent in both the sham and bioPLT (Figure 5). Hence, the processing steps, but not biotin itself led to activation of platelets. 7