Stabilization of standard platelet concentrates and minimization of the platelet storage lesion by a prostacyclin analogue

Abstract

Platelet concentrates were pretreated with a stable synthetic prostacyclin analogue (Iloprost) at two different concentrations before the second centrifugation step (pelleting step) of preparation. This resulted in loss of platelet sensitivity to aggregating agents. To mimic the situation after transfusion and to assess the reversibility of platelet inhibition, platelets were washed during and after storage and resuspended in fresh-frozen autologous plasma. The Iloprost-treated and washed platelets exhibited an increased sensitivity to the aggregating agents, compared with the control platelets (p less than 0.01). Post-storage recovery of the synergistic aggregation was more than 80% of prestorage aggregation. Beta-thromboglobulin (beta TG) release and thromboxane B2 (TXB2) formation were significantly inhibited in Iloprost-treated platelets (p less than 0.01). After the second centrifugation step, beta TG release was 0.7% +/- 0.3%, compared with 2.7% +/- 0.9% for the controls. TXB2 was 99 +/- 91 pg/ml, compared with 495 +/- 356 pg/ml for the controls. Platelet morphology and ultrastructure were well preserved during 5-day storage. In addition, Iloprost exerted a cytoprotective effect, as evidenced by the significant reduction in lactate dehydrogenase leakage. Post-storage LDH was 378 +/- 159 and 415 +/- 239 U/l respectively by the two Iloprost concentrations, compared with 1180 +/- 937 U/l for the control platelets. The inhibitory and cytoprotective effects of Iloprost were sustained throughout storage, in contrast to the effect of PGE1 (Prostin) which was limited to the early phase of storage.

Platelet binding and phagocytosis by macrophages

“…The PMA‐induced binding remains constant when PLTs are stored at 22°C, which makes it possible to investigate the regulation of phagocytosis. The binding appears for a major part mediated through P‐selectin expressed on the PLT surface because 1) it is absent in PLTs with blocked secretion by prostacyclin treatment, 7 2) present in PLTs that express P‐selectin, 29,31 and 3) inhibited by a P‐selectin antibody (this study). Inhibition by anti–P‐selectin is incomplete, suggesting that an additional mechanism might be involved that has yet to be identified.…”

“…Attempts to reduce the surface expression of recognition sites for PLT destruction were based on prostacyclin, which inhibits secretion and PS exposure; 7 arrest of glycolytic and oxidative energy generation, which inhibits ATP resynthesis required for PLT functions; 8,9 and storage at low temperature, which slows down PLT metabolism and in addition suppresses bacterial growth. Chilling of PLTs has long been thought to cause irreversible cell damage reflected by loss of the discoid shape and an increase in cytosolic Ca 2+ and causing poor posttransfusion survival 10,11 .…”

Transmission Electron Microscopy of Platelets FROM Apheresis and Buffy-Coat-Derived Platelet Concentrates

“…Most of the authors, using EM to investigate PLT vitality, refer to the influence of storage conditions on the morphological appearance of PLTs [12,68,[125][126][127][128][129][130]. Lactate accumulation may cause a pH fall in PC leading to a reduction of organelles and a progredient destruction of cell membranes [12,126].…”

“…These solutions provoke increasing PLT activation and increasing chemokine release during storage [127]. Elias et al described that a good maintenance of PLT ultrastructure could be achieved by adding a stable synthetic prostacyclin analogue (Iloprost) to the PC [128]. The chemical composition of storage bags can modify the adhesion of mononuclear cells to the plastic substrate of the PLT storage bag and the release of cytokines.…”