Platelets stored in a glucose-free additive solution or in autologous plasma--an ultrastructural and morphometric evaluation

Systems analysis of metabolism in platelet concentrates during storage in platelet additive solution

Platelets (PLTs) deteriorate over time when stored within blood banks through a biological process known as PLT storage lesion (PSL). Here, we describe the refinement of the biochemical model of PLT metabolism, iAT-PLT-636, and its application to describe and investigate changes in metabolism during PLT storage. Changes in extracellular acetate and citrate were measured in buffy coat and apheresis PLT units over 10 days of storage in the PLT additive solution T-Sol. Metabolic network analysis of these data was performed alongside our prior metabolomics data to describe the metabolism of fresh (days 1–3), intermediate (days 4–6), and expired (days 7–10) PLTs. Changes in metabolism were studied by comparing metabolic model flux predictions of iAT-PLT-636 between stages and between collection methods. Extracellular acetate and glucose contribute most to central carbon metabolism in PLTs. The anticoagulant citrate is metabolized in apheresis-stored PLTs and is converted into aconitate and, to a lesser degree, malate. The consumption of nutrients changes during storage and reflects altered PLT activation profiles following their collection. Irrespective of the collection method, a slowdown in oxidative phosphorylation takes place, consistent with mitochondrial dysfunction during PSL. Finally, the main contributors to intracellular ammonium and NADPH are highlighted. Future optimization of flux through these pathways provides opportunities to address intracellular pH changes and reactive oxygen species, which are both of importance to PSL. The metabolic models provide descriptions of PLT metabolism at steady state and represent a platform for future PLT metabolic research.

New Options for Multicomponent Collection (MCC) with the Latest Cell Separators

Recently, several new cell separators have become available for high platelet low WBC contamination thrombocytapheresis. In their original configuration, these apparatuses can only collect plasma along with platelets, while no concurrent red cell collection can be carried out. In this study, we present the preliminary results of plasma and/or erythrothrombocytapheresis after the adaptation of the lines of two different cell separators, namely the Fresenius AS 204 and the Baxter Health Care Amicus. In addition, the preliminary results of multicomponent collection using the Dideco Excel will be presented; in the latter a system of plasma recirculation was introduced, to increase the purity and quality of the platelet product. The results of these studies show that erythrothrombocytapheresis can be carried out with all these apparatuses, but only with Dideco-Excel and the Fresenius AS 204 the procedure is totally automated. There are marginal differences in the quality of the RBC product in terms of percent hematocrit, from 65% with the Excel and AS 204 to ∼ 75% with the Amicus and in terms total content of hemoglobin which averages 58 g per RBC concentrate when RBC collection is carried out during the processing of ∼ 420 ml of whole blood. In terms of platelet collection, the differences are presently moderate, as the platelet yield and WBC contamination are not affected by the concurrent RBC collection. The average platelet yield was 3.98-4.1, and 4.01x1011 and the total WBC contamination was 1.2-2.9, and 1.9X105 rerspectively with the Amicus, the AS 204 and the Excel. These represent a new step in the direction of total apheresis for blood and blood component procurement.

Platelet Additive Solutions: A Review of the Latest Developments and Their Clinical Implications

Summary Platelet additive solutions (PASs) have undergone many reformulations in order to further improve platelet storage. Studies of platelets stored in PAS-F (containing acetate, magnesium and potassium as key constituents) showed that platelets may be stored for 13 days with recovery and survival outcomes that are equal or even superior to 7-day stored platelets in plasma. Clinically, patients transfused with platelets in PAS have fewer allergic reactions, while for febrile reactions data are conflicting. Transfusion-related acute lung injury (TRALI) occurs less frequently if PAS is used for buffy coat-derived platelets, but for apheresis platelets there is no difference. For PAS-B and PAS-C, corrected count increments (CCIs) are lower than for platelets stored in plasma, but for PAS-E (like PAS-F also with acetate, magnesium and potassium but with additional phosphate), though limited data is available in the literature, the CCIs seem to be comparable to those observed for platelets in plasma. With platelets in PAS, there is an accumulated dilution effect of anticoagulant and PAS as well as a loss of number and function (due to storage and/or pathogen inactivation treatment) of platelets, of which it is not clear how this impacts clinical outcomes of patients undergoing massive transfusion. Worst-case in vitro studies, where the entire plasma fraction is replaced by supernatant of platelets in PAS, do show an effect on the ability of reconstituted whole blood to clot, but in a more realistic scenario, functional clotting parameters are not different. In this review, recent laboratory and clinical data are discussed, focusing on studies published after 2010.

Erythrothrombocytapheresis and Plasmathrombocytapheresis with Storage in T-sol of Platelets Collected by the New Amicus Cell Separator

The Amicus cell separator is the latest apparatus introduced into the international market for high-yield, low WBC contamination and short-procedure time thrombocytapheresis. In its original configuration the apparatus collects platelets for subsequent resuspension in plasma and no collection of PRBC can be carried out along with thrombocytapheresis. In this paper we present the results of plasma-thrombocytapheresis and erythro-thrombocytapheresis after the adaptation of the Amicus to the collection and storage of platelets in a non-plasma medium and the concurrent collection of PRBC. From our study it is concluded that PRBC collection doesn't modify the quality of the platelet product obtained from random donors (platelets pre-count 263×10e3/μl) in terms of yield which is 4.6×10e11 platelets, WBC contamination (1.3×10e5) or procedure time (63±26 min.). The quality of the platelet products is satisfactory too, as measured by aggregation induced by collagen and ristocetin or by the substantial stability of membrane glycoproteins (CD62 - 63 - 51 - 36 - 42B). The concentrate had an average content of 58.8 g of hemoglobin per bag, a final volume of 376 ± 13 ml, (after the addition of 100 ml of SAG-M) and a normal mechanic and osmotic fragility.

Transfusion reactions after transfusion of platelets stored in PAS-B, PAS-C, or plasma: a nationwide comparison

BACKGROUND

Platelets (PLTs) stored in PLT additive solution (PAS) are associated with fewer allergic reactions than plasma-stored PLTs. However, earlier studies could not provide conclusive evidence on febrile reactions and did not analyze other transfusion reactions separately due to limited sample size. We therefore compared incidences of all transfusion reactions of PAS-B-PLTs, PAS-C-PLTs, and plasma-PLTs.

STUDY DESIGN AND METHODS

In this observational study, all transfusion reactions reported to the national hemovigilance office of the Netherlands from 2006 to 2015 were included.

RESULTS

During the study period, a total of 2407 transfusion reactions after PLT transfusions were reported. In that period 553,267 pooled buffy coat-derived PLT units were issued, of which 83,884 were stored in PAS-B, 45,728 in PAS-C, and 423,655 in plasma. Regarding transfusion-related circulatory overload, transfusion-related acute lung injury, and "other reactions" no significant differences were observed between the PLT products. When PAS-B-PLT transfusions were compared to plasma-PLT transfusions, the overall relative risk (RR; 95% confidence interval [CI]) of transfusion reactions was 0.99 (0.88-1.11); for allergic and febrile nonhemolytic transfusion reactions (FNHTRs) it was 0.66 (0.55-0.80) and 1.54 (1.27-1.86), respectively. When PAS-C-PLTs were compared to plasma-PLTs, the RR (95% CI) was 0.56 (0.46-0.68) for all transfusion reactions, 0.38 (0.28-0.52) for allergic reactions, and 0.82 (0.59-1.13) for FNHTRs. When PAS-C-PLTs were compared to PAS-B-PLTs, for all reactions the RR (95% CI) was 0.56 (0.45-0.70) for allergic reactions 0.58 (0.40-0.82), and for FNHTRs 0.53 (0.37-0.75).

CONCLUSIONS

PAS-C-PLTs are associated with fewer transfusion reactions compared to plasma-PLTs and compared to PAS-B-PLTs.

Evaluation of Different Preparation Procedures of Pathogen Reduction Technology(Mirasol®)-Treated Platelets Collected by Plateletpheresis

SUMMARY: BACKGROUND: The Mirasol® pathogen reduction technology (PRT) for platelet concentrates (PC) uses riboflavin and UV light (270-360 nm). We evaluated the impact of PRT on platelets in comparison to standard single-donor PC. MATERIAL AND METHODS: Platelets were resuspended in autologous plasma. After 2 h rest without agitation, PC were split into an untreated control unit (C-PC) and an immediately treated unit (T-PC) (series I). In series IV, split PC were stored under agitation over night before PRT was carried out. Platelet quality was assessed by pH, glucose consumption, lactate production rate, LDH, soluble sCD62p and CD62p expression with and without TRAP (thrombin receptor-activating peptide) over 7 days. RESULTS: SERIES I: On day 5, pH values were lower for T-PC (6.8 ± 0.2 vs. 7.4 ± 0.1, C-PC), accompanied by a higher glucose consumption rate of 0.069 ± 0.016 vs. 0.035 ± 0.006 mmol/10(12) platelets/h and lactate production rate of 0.126 ± 0.031 vs. 0.063 ± 0.011 mmol/10(12) platelets/h. CD62p using TRAP was lower for T-PC (50 ± 11 vs. 62 ± 14%). Baseline activation was higher in T-PC (35 ± 12 vs. 28 ± 15%). Longer initial rest time had no impact on these results (series II/III/IV). CONCLUSION: PRT leads to an increase of platelet metabolism and activation independent of the length of the initial rest times. PC resuspended in autologous plasma should be stored at maximum up to day 5.

Buffy-coat platelet variables and metabolism during storage in additive solutions or plasma

BACKGROUND

Buffy-coat processing allows for the use of platelet additive solutions (PASs). PASs reduce plasma-associated transfusion reactions and conserve plasma for transfusion or fractionation. Platelet (PLT) storage in plasma was compared to storage in three commercially available PASs compared to assess their influence on in vitro laboratory variables.

STUDY DESIGN AND METHODS

Platelet concentrates (PCs) were prepared from leukoreduced pools of four buffy coats (BCPs) suspended in autologous plasma or one of PASs (Composol, Fresenius-Kabi; T-Sol, Baxter Corp.; or SSP+, MacoPharma). On Days 1, 2, 3, 5, and 7 of storage, samples were tested for PLT concentration, mean PLT volume (MPV), CD62P, morphology, pO2, pCO2, glucose, lactate and total protein concentration, pH, extent of shape change (ESC), and hypotonic shock response (HSR). Data were analyzed by analysis of variance (ANOVA) with repeated measures and t tests.

RESULTS

PLT recoveries from BCPs were higher (p < 0.05) with plasma than any PAS. Storage medium and duration did not affect PLT concentration or MPV over time. CD62P expression and morphology were significantly different among PCs pooled with different media. ANOVA showed (p < 0.05) differences among the rates of change of pCO2, pH, glucose consumption, lactate production, and ESC; PASs such as Composol and SSP+ offered excellent maintenance of pH and low rates of glucose consumption. PAS performed poorly in ESC and HSR compared to plasma. Correlation studies reveal far more significant correlations between variables of PLTs in PAS than in plasma.

CONCLUSION

Newer PASs, for example, SSP+ and Composol, can maintain PLT integrity and moderate metabolism similarly to plasma but offer consistently lower PLT recoveries and limited osmotic balance.

In vitro function of buffy coat-derived platelet concentrates stored for 9 days in CompoSol, PASII or 100% plasma in three different storage bags

BACKGROUND AND OBJECTIVES

The aim of the study was to compare the in vitro quality of buffy coat-derived platelet concentrates (PC) during extended storage in plasma or additive solution in three different storage bags.

MATERIALS AND METHODS

A pooled and split design was chosen so that identical PCs were produced in either 100% plasma, 70% PASII : 30% plasma or 70% CompoSol : 30% plasma (n = 6 each). This was repeated for three different manufacturers' platelet storage bags (Fresenius, Baxter and Pall). PCs were sampled on days 1, 5, 7 and 9 of storage and tested in vitro using a variety of tests of platelet function. For each bag type, storage in PASII or Composol was compared with plasma (data taken across the entire storage period), and differences occurring with time were analysed for all storage media.

RESULTS

The pH of all PCs was > 6.8 at day 9 of storage. In vitro platelet function, as assessed by markers of platelet activation and metabolism, of PCs stored in CompoSol appeared to be similar to that of PCs stored in plasma over 9 days of storage. In contrast, PCs stored in PASII tended to have significantly higher levels of platelet activation (almost a twofold increase in % platelets positive for CD62P by day 5) and lower hypotonic shock response (approximately 40%, by day 7) compared to either PCs stored in 100% plasma or 70% CompoSol. The magnitude of the differences observed between platelet storage media appeared to be dependent on the type of platelet storage bag with the highest degree of platelet activation and lowest hypotonic shock response values being observed in Fresenius bags in combination with PASII.

CONCLUSIONS

The maintenance of platelet function in vitro during extended storage of PCs in platelet additive solutions is dependent on the combination of type of additive solution and type of platelet storage bag. For all bag types studied, storage in PASII resulted in poorer platelet function in vitro.

In vitro function of platelet concentrates prepared after filtration of whole blood or buffy coat pools

BACKGROUND/METHOD

Data on the quality of platelet concentrates (PC) produced by the buffy coat method and stored beyond 5 days in plasma are limited. We therefore evaluated the quality of PCs prepared by leucocyte depletion of whole blood (Terumo WBSP, n = 10) or a buffy coat pool (Pall Autostop, n = 10), and stored for 7 days in plasma by assessing platelet parameters and markers of platelet activation.

RESULTS

In both types of PC, levels of glucose decreased during storage but were not totally depleted (> 11 mM on day 7). In contrast, lactate levels increased on storage and was consistently < 20 mM throughout, with pH maintained at > 6.8 in all units. Hypotonic shock response scores were > 47% in all units at day 7. On day 1, markers of platelet activation were significantly higher in WBSP PC, but by day 7 were similar for percentage CD63+ and CD62P + (40%) with levels of platelet microparticles and annexin V binding two-fold higher in WBSP. The expression of CD61 did not alter during storage and the percentage of platelets expressing CD42b was > 88% in all units on day 7. RANTES (Regulated on activation, normal, T-cell expressed and secreted) and TGFbeta released from platelets by day 7 was < 800 ng/ml and 90 ng/ml, respectively. C3a(desarg) increased throughout storage in both types of PC, but without a commensurate increase in the terminal complex SC5b-9 or activation of factor XII.

CONCLUSION

Our data indicates that the in vitro characteristics of PCs prepared using these methods is maintained over storage for 7 days in plasma and is not associated with significant deterioration of platelet function. ONE SENTENCE SUMMARY: In vitro function of platelet concentrates prepared by either filtration of whole blood, or pooled buffy coats.

Fully automated processing of buffy-coat-derived pooled platelet concentrates

BACKGROUND

The OrbiSac device, which was developed to automate the manufacture of buffy-coat PLT concentrates (BC-PCs), was evaluated.

STUDY DESIGN AND METHODS

In-vitro characteristics of BC-PC preparations using the OrbiSac device were compared with manually prepared BC-PCs. For standard processing (Std-PC, n = 20), four BC-PCs were pooled using 300 mL of PLT AS (PAS) followed by soft-spin centrifugation and WBC filtration. The OrbiSac preparation (OS-PC, n = 20) was performed by automated pooling of four BC-PCs with 300 mL PAS followed by centrifugation and inline WBC filtration. All PCs were stored at 22 degrees C. Samples were withdrawn on Day 1, 5, and 7 evaluating PTL count, blood gas analysis, glucose, lactate, LDH, beta-thromboglobulin, hypotonic shock response, and CD62p expression.

RESULTS

A PLT content of 3.1 +/- 0.4 x 10(11) (OS-PCs) versus 2.7 +/- 0.5 x 10(11) (Std-PCs, p < 0.05) was found. A CV of 19 percent (Std-PC) versus 14 percent (OS-PC) suggests more standardization in the OS group. At Day 7, the Std-PCs versus OS-PCs showed a glucose consumption of 1.03 +/- 0.32 micro mol per 10(9) PLT versus 0.75 +/- 0.25 micro mol per 10(9) PLT (p < 0.001), and a lactate production of 1.50 +/- 0.86 micro mol per 10(9) versus 1.11 +/- 0.61 micro mol per 10(9) (p < 0.001). The pH (7.00 +/- 0.19 vs. 7.23 +/- 0.06; p < 0.001), pO(2) (45.3 +/- 18 vs. 31.3 +/- 10.4 mmHg; p < 0.01), and HCO(3) levels (4.91 +/- 1.49 vs. 7.14 +/- 0.95 mmol/L; p < 0.001) suggest a slightly better aerobic metabolism within the OS group. Only small differences in CD62p expression was observed (37.3 +/- 12.9% Std-PC vs. 44.8 +/- 6.6% OS-PC; p < 0.05).

CONCLUSION

The OrbiSac device allows an improved PLT yield without affecting PLT in-vitro characteristics and may enable an improved consistency in product volume and yield.

Implementation of the INTERCEPT Blood System for Platelets into routine blood bank manufacturing procedures: evaluation of apheresis platelets

BACKGROUND AND OBJECTIVES

The INTERCEPT Blood System for Platelets utilizes amotosalen-HCl (S-59) in combination with ultraviolet A (UVA) light to inactivate viruses, bacteria, protozoa and leucocytes that may contaminate platelet concentrates (PCs). To facilitate implementation of this technique into routine blood bank manufacturing procedures, this study evaluated the impact of different time settings of photochemical treatment on in vitro platelet function.

MATERIALS AND METHODS

Platelets derived from apheresis (6.5-7.0 x 10(11) platelets) were resuspended in 240 ml of autologous plasma and 360 ml of platelet additive solution (PAS III) and split into two equal-sized PC units. Whereas one unit was not treated, the other was treated with 150 microm amotosalen and 3 J/cm2 UVA light followed by a compound adsorption device (CAD) step for reduction of residual amotosalen and photoproducts. In a first series of experiments (arm A, n = 7), PC units were photochemically treated after an overnight storage period of 16-23 h followed by a CAD step of 4 h. In a second series (arm B, n = 8), photochemical treatment occurred after a short storage time of 4 h with a subsequent CAD step of 16 h. Platelet function was evaluated by assaying blood gas analysis, glucose and lactate concentration, lactate dehydrogenase (LDH), hypotonic shock response (HSR) and the expression of CD62p, over a period of 7 days.

RESULTS

Neither of the photochemical treatment procedures showed differences for pH, pCO2, pO2, HCO3, glucose consumption or platelet activation until the end of day 7. Increased lactate values detected for the treated units of arm A at the end of the storage period were independent from the PCT time setting.

CONCLUSIONS

Photochemical pathogen inactivation with different initial resting periods between 4 and 23 h, and different CAD steps of 4 and 16 h, had no influence on the platelet in vitro function during 7 days of storage.

Influence of cell-free DNA in plasma on real-time polymerase chain reaction for determination of residual leucocytes in platelet concentrates

BACKGROUND AND OBJECTIVES

Real-time quantitative (RQ) polymerase chain reaction (PCR) can be used to determine the number of residual leucocytes in leucocyte-reduced platelet concentrates (LR-PCs), which should contain < 3.3 leucocytes/ micro l. In this study we investigated the extent to which cell-free DNA, known to be present in plasma, might interfere with this determination. In this study, RQ-PCR was employed to determine the following: the influence of filtration of platelet concentrates (PCs) on the amount of cell-free DNA; the variation in concentration of cell-free DNA between the buffy coats (BCs) of different donors; and the amount of cell-free DNA during storage and processing of whole blood.

MATERIALS AND METHODS

PCs were sampled before and after filtration (n = 5), BCs were sampled (n = 100) and whole blood units were sampled < 2 h and 16-20 h after collection, and the BCs were also sampled after processing the whole blood (n = 10). Samples were centrifuged to obtain cell-free plasma in which the amount of cell-free DNA was determined using an RQ-PCR for the albumin gene.

RESULTS

The amount of cell-free DNA was not influenced by filtration of the PCs [1.7 +/- 0.8 vs. 1.5 +/- 0.8 leucocyte-equivalents (eq)/ micro l]. However, the amount of cell-free DNA in plasma of the BCs varied considerably, from 0.1 to 18.2 leucocyte-eq/ micro l (median = 1.5 leucocyte-eq/ micro l; mean +/- SD: 2.2 +/- 2.4 leucocyte-eq/ micro l). In 18% of the BCs the amount cell-free DNA was > 3.3 leucocyte-eq/ micro l. The amount of cell-free DNA increased during storage, from 0.3 +/- 0.3 leucocyte-eq/ micro l (< 2 h after collection) to 0.9 +/- 0.6 leucocyte-eq/ micro l (16-20 h after collection) and, after processing the whole blood, to 2.0 +/- 2.0 leucocyte-eq/ micro l.

CONCLUSIONS

Variable amounts of cell-free DNA in plasma will interfere if RQ-PCR is applied to estimate leucocyte numbers in leucocyte-reduced PCs.

Ultrastructural changes and activation differences in platelet concentrates stored in plasma and additive solution

BACKGROUND

The aim of this study was to demonstrate how ultrastructural morphology of platelets stored in different media correlate with the appearance of particular activation markers on their cell surface.

STUDY DESIGN AND METHODS

Concentrates of buffy coat-derived platelets were stored in plasma or a glucose-free citrate-acetate-NaCl platelet additive solution (PAS2, Baxter Healthcare Corp.). Activation markers on platelets were measured by flow cytometry and compared with changes in the platelet cell surface as demonstrated by electron microscopy. Levels of the vasoactive cytokines vascular endothelial growth factor (VEGF) and RANTES (regulated upon activation, normal T-cell expressed and secreted) were determined in the storage medium of the platelet concentrate.

RESULTS

The activation markers CD62P and CD63 and the binding of thrombospondin measured by flow cytometry were expressed to a higher extent in the PAS2 group compared with the plasma group. The difference reached significance on Day 3 (CD62P: 66.37 +/- 2.44 vs. 37.83 +/- 2.03, p < 0.001; CD63: 42.11 +/- 3.29 vs. 34.84 +/- 2.04, p < 0.05; and thrombospondin binding: 18.84 +/- 3.9 vs. 13.98 +/- 3.87, p < 0.001, respectively). The form factor that is related to changes of the platelet shape was determined by image analysis and correlated significantly with the cell surface expression of CD62P (p < 0.001) and with CD63 (p < 0.05) and with thrombospondin binding (p < 0.05). The chemokines VEGF and RANTES were measured at higher levels in the PAS2 group.

CONCLUSIONS

With exception of baseline activation probably due to necessary handling procedures, platelets remain relatively unaltered and more stable in plasma in comparison to storage in PAS2.

WBC-reduced platelet concentrates from pooled buffy coats in additive solution: an evaluation of in vitro and in vivo measures

BACKGROUND

The use of a platelet additive solution (PAS-II, Baxter) may have benefits over plasma for storage of platelets. It was the aim of this study to develop a method to produce WBC-reduced platelet concentrates (PCs) in PAS-II with >240 x 10(9) platelets and <1 x 10(6) WBCs per unit, which can be stored for 5 days at pH >6.8 and that will give sufficient platelet increments after transfusion: a 1-hour CCI of >7.5 and a 20-hour CCI of >2.5.

STUDY DESIGN AND METHODS

PCs were made from five pooled buffy coats and 250 g of PAS-II. After centrifugation the PCs were WBC-reduced with a filter (Autostop BC, Pall Biomedical) and stored in a 1000-mL polyolefin container. CCIs were assessed in stable hemato-oncologic patients after 5-day old PCs were transfused.

RESULTS

Routinely produced PCs contained a median of 310 x 10(9) platelets (n = 5,363) with 3.5 percent containing <240 x 10(9) platelets, in a median volume of 320 mL (n = 11,834). The median number of WBCs was <0.03 x 10(6) (n = 694). The WBC count exceeded 1 x 10(6) in three PCs, but it was always <5 x 10(6), giving 99-percent confidence that more than 99.5 percent of the units will contain <1 x 10(6) WBCs. The pH remained >6.8 on Day 8, provided the concentration was below 1.1 x 10(9) platelets per mL (n = 32). After 28 transfusions in 28 patients, the 1-hour CCI was 12.6 +/- 4.3 (mean +/- SD, with 2/28 CCIs <7.5) and the 20-hour CCI was 8.9 +/- 5.6 (with 4/28 CCIs <2.5). Limitations of this study include the absence of a control group of patients receiving platelets stored in plasma and of in vivo radiolabeled survival studies, but a comparison of these data with previously published data suggested that the in vivo survival of platelets stored in PAS-II is less than that of platelets stored in plasma.

CONCLUSION

The WBC-reduced PCs conformed to specifications. These WBC-reduced PCs could be stored at least 5 days with maintenance of pH, and they gave sufficient increments after transfusion to patients.

Platelet storage in PAS-2 or autologous plasma: impact on functional parameters

Currently, several platelet additive solutions for long-term platelet storage have been introduced. The aim of this study was to compare the deterioration of functional status of platelets stored for up to 5 days in autologous plasma (AP) only, with platelet stored in PAS-2, a salt solution containing acetate, citrate and sodium chloride. Change in platelet adhesion, aggregation and activation was measured by flow cytometric technique. In addition, beta-Thromboglobulin (beta-TG), lactate and glucose were determined. After 5 days of storage, the expression of P-Selectin was significantly higher, the production of lactate and the consumption of glucose were significantly lower, in platelets stored in PAS-2 than in autologous plasma. No significant differences were detected on day 5 between the two groups with regard to fibrinogen, von Willebrand factor binding capacity, or to beta-TG release. It can be concluded that neither storage medium was consistently better for the parameters tested. However, it must be emphasized that platelets stored in autologous plasma exhibited less lesion, in terms of P-Selectin expression compared with platelets stored in PAS-2.

New plasma-reduced synthetic media, Fukushima cocktails, for the storage of platelets for transfusion

BACKGROUND

Donor plasma proteins are associated with non-hemolytic allergic reactions, such as urticaria or laryngeal edema, in platelet-transfusion recipients. Replacement of plasma with synthetic media from platelet concentrates (PCs) is considered to be effective in preventing such reactions. However, platelets preserved in media depleted of less than 10% plasma are reported to have functions inferior to those preserved in plasma.

METHODS

Fukushima Cocktails (FCs) contain glycerol (25, 50 or 100mM), sodium acetate, glucose and other components. To test the effect and determine the most suitable concentration of glycerol for platelet preservation, functions of platelets including aggregation, hypotonic shock response and swirling pattern and released biochemicals were measured with platelets preserved in Fukushima Cocktails. The effects of residual plasma on platelet functions were also evaluated. Autologous platelets stored for 3 days in solution containing 50 mM glycerol were transfused into healthy volunteer donors to evaluate their safety and survival.

RESULTS

The functions (aggregation and hypotonic shock response) of platelets preserved in Fukushima Cocktails with 10% residual plasma were preserved for 5-7 days as well as plasma controls, whereas platelets stored for 9 days in a medium lacking glycerol became swollen and beta-thromboglobulin and thromboxane B(2) increased. When the residual plasma was more than 5%, platelet functions including aggregation, hypotonic shock response and swirling pattern were well preserved for 7 days. The in vivo platelet survival rates at 24 and 48 h after transfusion of platelets stored for 3 days in Fukushima Cocktail were 77% and 60%, respectively, which were not less than autologous plasma-stored platelets.

CONCLUSION

Glycerol at a concentration of around 50 mM has a beneficial effect on platelet preservation for more than 7 days. The results of these experiments indicate that platelets stored in Fukushima Cocktail should be useful clinically.

The flow rate significantly influences the leukocyte depletion rate during prestorage in-line filtration of platelet concentrates

BACKGROUND

White cell reduction of blood products minimizes the risks of alloimmunization against HLA-antigens, the transmission of viral diseases and the incidence of platelet transfusion reactions. One modern strategy is leukocyte depletion with an integrated filter system immediately after preparation and prior to storage.

STUDY DESIGN AND METHODS

We evaluated the efficiency of a novel in-line filter system Sepacell PLX-5 BPS for leukocyte reduction of platelet concentrates (PC) from pooled buffy-coats. A total of 44 PCs were investigated with regard to different filtration flow rates (25-110 ml/min) and leukocyte depletion and thrombocyte recovery rates were analysed. Furthermore, we studied the influence of filtration on PCs over a storage period of 6 days (n = 12) by investigation of pH, lactate and glucose. Platelet function was determined by means of hypotonic shock response, external shape change and expression of CD62p.

RESULTS

The mean leukocyte depletion rate was > log 5. After filtration the mean leukocyte count was 0.12 +/- 0.21 x 10(6). In 60% of the PCs the leukocyte count lay below the detection level of the Nageotte chamber, which is < 0.3 x 10(5). The flow rate correlates significantly with the leukocyte count in the PCs (r = 0.325; p = 0.033) and therefore with the leukocyte depletion rate (r = -0.422; p = 0.01). Flow rates under 40 ml lead to a significantly lower leukocyte contamination. Only in one PC, at a flow rate of 84 ml/min, was the leukocyte threshold of 1 x 10(6) exceeded. We did not find a significant correlation between filtration flow rate and thrombocyte recovery (r = 0.315; p = 0.069). The mean platelet count in the PC was 2.88 +/- 0.47 x 10(11). Compared with the thrombocyte count in the pooled buffy coat, the recovery was 68.6%. We observed a decrease of pH, glucose, external shape change and hypotonic shock response over the storage period while lactate and the expression of CD62p increased.

CONCLUSION

The filter system Sepacell PLX-5 BPS proved to be suitable for in-line filtration of platelet concentrates prior to storage. Filtration flow rates of up to 40 ml/min allowed efficient leukocyte depletion without significant loss in the quality of the platelet concentrates and the platelet function in vitro.

Dry platelets with the Dideco Excel apparatus

Dry platelets are required to prevent hemolytic and nonhemolytic febrile reactions after transfusion to ABO mismatched recipients, to reduce the risk of HLA immunization and to prevent allergic or anaphylactic reactions. Previously we have shown that the collection of single donor platelets almost free of plasma is possible with different cell separators. With the systems we described for the CS 3000+/Amicus and AS 104-204 apparatuses collection of dry platelets implies their resuspension in non plasma solutions after opening the circuit. With the new system developed by Dideco for the Excel apparatus this moreover is no longer required since the platelet bag can be connected to the resuspending medium through a dedicated line with an antibacterial filter. Platelets are collected cyclically and the resuspending solution is added when the procedure is over. In this study 53 collections were evaluated, 21 of which were erythrothrombocytapheresis. In 60-65 min 4.21 of anticoagulated blood (1/12) were processed with platelet collection automatically done after 6-700 ml cycles. The platelet yield averaged 4.67 +/- 0.7 x 10(11), with a platelet efficiency per minute of 7.18 +/- 0.9 x 10(9). The WBC contamination averaged 2.6 +/- 0.7 x 10(5) and contamination did not exceed 0.87 x 10(6). The quality of platelets was satisfactory as measured by aggregation, morphology score, and CD 62 membrane glycoprotein externalization. These results were comparable to those obtained with three other Excel apparatuses used in the conventional way to collect platelets resuspended in plasma or with the Amicus used to collect dry platelets using an open system.

In-process cell counts during preparation of platelet concentrates from buffy coats

To ensure the quality of platelet concentrates (PCs), we studied in-process recoveries of blood cell counts in pooled PCs derived from four or five buffy coats (BCs) from Biopack Compoflex Systems in Bern (PC-BC/4 or PC-BC/5) and from five BCs from Optipac (Baxter) in Zurich (PC-BC/5). BCs were pooled employing a sterile connecting device and flushing them with 300 mL of platelet additive solution. The pools were centrifuged for 12 min at 500 g at 20 degrees C and filtered with PALL's Auto-Stop BC-leukocyte removal filter. Automated platelet counting was performed on whole blood donation, on single BC, on pooled BC and in the final product. Four out of 10 PC-BC/4 (= 40%) and 29 out of 30 PC-BC/5 (= 97%) had a total platelet count of > 200 x 10(9) platelets. Average percentage recoveries in PC compared to the pre-centrifugation BC pools were similar with the Biopack Compoflex and the Optipac systems, 62% and 57% respectively, whereby the absolute platelet count per one donation was similar, i.e. 49.5 x 10(9), 55 x 10(9) and 53 x 10(9) in PC-BC/4 and PC-BC/5 from Bern and PC-BC/5 from Zurich. There was a significant positive correlation between the inital number of BCs taken for pooling and the final platelet counts in the PCs. In order to recover a minimal platelet content of 200 x 10(9) platelets per pooled unit, it is safer to start out with five rather than with four donations unless recoveries during the production steps can be improved.