Pooled Platelet Concentrates Prepared by the Platelet-Rich-Plasma Method and Filtered with Three Different Filters and Stored for 8 Days

Pooled platelet concentrates (PC) prepared by the platelet-rich plasma (PRP) method were filtered with three different filters and stored for 8 days at room temperature. The effect of filtration on leukocyte contamination, platelet concentration, and the in vitro function, morphology, metabolism and activation of platelets were studied. Eight pools of 20 PRP-PC were used, each pool was split into 4 equal volumes; 3 were filtered over a PL50HF, a PL-10A and a Bio P10 filter, the 4 served as a control. After filtration, leukocyte counts exceeded 3×10⁵ in none of the pooled PC. Platelet loss induced by filtration was about 17%. During storage, no differences in pH, PCO₂, and lactate and glucose concentration were found between the filtered and the unfiltered units, nor were any differences observed between filtered and unfiltered pooled PC in aggregation upon stimulation with collagen and/or ADP, adhesion capacity to collagen in flowing blood, nucleotide content of the platelets and nucleobase concentration in the plasma, expression of activation-dependent antigens, or platelet morphology as observed by light microscopy and by the swirling effect. Selective removal of β-thromboglobulin (22%) by the PL50HF filter was observed. Pooled PC prepared by the PRP-method can be filtered and stored for 8 days without detrimental effect on platelet function, metabolism or activation.     

A Comparative Study of Platelets Stored in Polyvinyl Chloride Containers Plasticised with Butyryl Trihexyl Citrate or Triethylhexyl Trimellitate

Platelet concentrates (PCs), stored for 5 days in PL 2209, a new polyvinyl chloride (PVC) storage container plasticised with butyryl trihexyl citrate, were compared with those stored in PL 1240, a PVC platelet container plasticised with triethylhexyl trimellitate. In part 1 of the study, pooled platelet-rich plasma (PRP) was aliquoted into each type of pack and pH, pCO₂, pO₂, hypotonic shock response, aggregation responses, lactate, glucose and ATP concentrations, and lactate dehydrogenase and β-thromboglobulin release were compared at days 1, 3 and 5. In part 2, 12 volunteers gave a unit of blood on two separate occasions and PCs produced by the PRP method were stored in PL 2209 or PL 1240 for 5 days before autologous reinfusion of a ¹¹¹In-labelled sample. In vitro results demonstrated that PL 2209 was more gas permeable than PL 1240. In part 2 of the study, at day 5, pCO₂ was 3.13±0.62 versus 5.14±0.69 (p<0.001), whilst pO₂ was not significantly different for PL 2209 versus PL 1240, respectively. pH was better maintained in PL 2209 than in PL 1240 (7.38±0.13 vs. 7.24±0.10, respectively, p<0.01) after storage for 5 days. These results were confirmed by those from part 1. In vivo data were similar for PC stored in the two plastics with a multiple-hit recovey of 40.9±12.1% for PL 2209 and 37.4±11.3% for PL 1240, and a multiple-hit survival of 4.89±1.20 days and 5.28±2.06 days for PL 2209 and PL 1240, respectively. γ-Camera imaging of volunteers showed similar biodistribution of radiolabeled platelets stored in each container. These results demonstrate that PL 2209 is a suitable container for storage of PCs for 5 days.     

Normal Viability of Platelet Concentrates Obtained from CPDA-1 Blood after Storage in CL-3000 Blood Containers

Platelet concentrates were obtained from blood anticoagulated with CPDA-1 and their viability after storage in CL-3000 containers for 72 h at 22°C and for 24 and 48 h at 4°C was studied using autologous reinfusion of ⁵¹Cr-labeled platelets. Yield and t_1/2 values after such storage were similar to those previously reported for other containers and anticoagulants. Survival of platelets stored at 22°C for 3 days was essentially normal with the expected yields for that duration of storage. As has been described for other containers, adenine has no adverse or beneficial effect on platelet viability when assessed with these methods.     

Clinical Evaluation of the Effects of Storage Time and Irradiation on Transfused Platelets

Platelet concentrates stored for up to 5 days at room temperature or irradiated with 15 Gy immediately prior to transfusion were evaluated for their ability to increase the platelet count in thrombocytopenic patients. Platelets irradiated with a dose of 15 Gy immediately prior to transfusion achieved corrected increments (CI) at 1 and 20 h after transfusion no different from those achieved by non-irradiated platelets. Storage for 5 days reduced the mean 1-hour CI to 5.7 compared with a mean of 12.3 achieved by platelets transfused after only 1-day storage (p = 0.008). Similarly, the frequency of a repeat transfusion being indicated within 24 h increased with increasing storage time (p = 0.005).     

Ultraviolet-B irradiation of platelets induces a dose-dependent increase in the expression of platelet activation markers with storage

Summary. Ultraviolet B (UVB) irradiation of platelet concentrates (PCs) has been proposed as a novel technology to prevent HLA sensitization. We have recently reported that 2 J/cm² of UVB radiation abolishes alloreactive lymphocyte responses in vitro. In order to increase the efficacy of UV irradiation for the prevention of HLA sensitization, we exposed PCs to 4 or 8 J/cm² of UVB and evaluated the effect of UV radiation on platelet integrity during storage. We report here that UV exposed platelets show a progressive increase in the expression of activation markers P-selectin (GMP-140; CD62) and LIMP-CD63 (GP-53; CD63) on the platelet membrane over time in a dose-dependent manner compared to age-matched controls. Platelet metabolism was also enhanced as evidenced by significant changes in lactate and pH during post-irradiation storage. Based on these findings we transfused PCs within 4 h after UV irradiation. PCs exposed to 4 J/cm² showed normal post-transfusion recoveries and haemostatic functions, while poor platelet recoveries were found after administration of PCs exposed to 8 J/cm². We hypothesize that the rapid expression of P-selectin on platelets exposed to the higher dose of UVB leads to an increased binding of these platelets to leucocytes in the circulation resulting in poor platelet recoveries.     

The effects of selective serotonin reuptake inhibitors on platelet function in whole blood and platelet concentrates

Several studies report that patients who are treated with selective serotonin reuptake inhibitors (SSRIs) for depression may have increased risk of bleeding, particularly from the gastrointestinal tract. This may be related to low intraplatelet serotonin concentrations. Several blood banks do not store platelets from donors using SSRIs for transfusion, although the possible effects of SSRIs on platelet storage are not documented. We conducted a case-control pilot study of apheresis platelet concentrates prepared from donors using SSRIs (n?=?8) and from donors without medication (n?=?10). The platelet concentrates were stored for 5 days. Light transmission aggregometry (LTA), thrombelastography (TEG), and flow cytometric analyses were preformed for in vitro measurements of platelet function. Platelet function and platelet serotonin content were investigated in whole blood and in platelet concentrates stored for up to 5 days. LTA, TEG, and flow cytometric analysis of glycoprotein expression did not reveal any significant differences between the two groups. All 18 platelet concentrates performed well according to the standards set for platelet quality in relation to transfusion. Blood donors using SSRIs had significantly lower platelet serotonin compared to blood donors without medication. The results from our pilot study indicate that platelets from donors using SSRIs may be suitable for transfusion after storage for 5 days, but further laboratory and clinical studies are necessary to confirm this.     

The effects of selective serotonin reuptake inhibitors on platelet function in whole blood and platelet concentrates

Several studies report that patients who are treated with selective serotonin reuptake inhibitors (SSRIs) for depression may have increased risk of bleeding, particularly from the gastrointestinal tract. This may be related to low intraplatelet serotonin concentrations. Several blood banks do not store platelets from donors using SSRIs for transfusion, although the possible effects of SSRIs on platelet storage are not documented. We conducted a case-control pilot study of apheresis platelet concentrates prepared from donors using SSRIs (n=8) and from donors without medication (n=10). The platelet concentrates were stored for 5 days. Light transmission aggregometry (LTA), thrombelastography (TEG), and flow cytometric analyses were preformed for in vitro measurements of platelet function. Platelet function and platelet serotonin content were investigated in whole blood and in platelet concentrates stored for up to 5 days. LTA, TEG, and flow cytometric analysis of glycoprotein expression did not reveal any significant differences between the two groups. All 18 platelet concentrates performed well according to the standards set for platelet quality in relation to transfusion. Blood donors using SSRIs had significantly lower platelet serotonin compared to blood donors without medication. The results from our pilot study indicate that platelets from donors using SSRIs may be suitable for transfusion after storage for 5 days, but further laboratory and clinical studies are necessary to confirm this.     

Clinical Experience with Transfusion of Cryopreserved Platelets

S ummary . Multiple units of platelet concentrate obtained by plateletpheresis of normal, 'random'or HL-A matched donors were pooled and frozen in polyolefin bags using 5% dimethylsulphoxide (DMSO) as a cryoprotective agent and a controlled freezing rate of 1°/min. The platelets were stored at approximately — 120° C for as long as 201 days, thawed rapidly at 37°, washed once and resuspended in ACD plasma prior to transfusion. Two different final concentrations of platelets (˜ 2.7 and 9.0 × 10¹²/1.) were studied. Twenty-three thrombocytopenic patients have received a total of 40 frozen platelet transfusions. The mean freeze-thaw loss was 21% and was similar for both platelet concentrations. All transfusions were well tolerated and there were no side effects attributable to the small amounts of DMSO infused. Increments in platelet counts I h after transfusion ranged from 0 to 102 × 10⁹/1. with an overall mean corrected increase in evaluable patients of 12 800 (increase × surface area (m²)/number of platelets transfused × 10¹¹). Corrected increases tended to be greater with the low concentration of platelets. Overall, the increase in count for the frozen platelet transfusions was 65% of the increments obtained with fresh platelet transfusions administered within I week of the frozen platelets. Bleeding times were partially corrected after four out of six transfusions with post-transfusion counts greater than 50 × 10⁹/1., and active haemorrhage was controlled in some patients by frozen platelet transfusions. These results indicate that pooled platelets can be frozen, thawed and transfused with reasonable efficiency. The frozen platelets can circulate and function haemostatically and may eventually play an important role in supportive care.     

Removal of Leukocytes from Whole Blood and Erythrocyte Suspensions by Filtration through Cotton Wool

Abstract. Units of packed red cells, derived from CPD blood, were stored for 2 or 7 days at 2°C. Using the filtration method described earlier, practically all leukocytes were removed. After filtration, the erythrocyte suspensions were again stored for 2 or 7 days at 2°C. The red cells were then labelled with Na₂ ⁶¹CrO₄ and infused into the original donors. The survival of the red cells was determined 24 and 48 h after infusion.
Comparison to the data obtained after transfusion of labelled but unfiltered packed cells derived from CPD blood and stored for 14 or 17 days in PVC bags showed no differences in viability.     

Platelet concentrates irradiated with ultraviolet light retain satisfactory in vitro storage characteristics and in vivo survival

We have previously reported that platelet concentrates (PC) may be irradiated with ultraviolet light (UVL) in a cryostorage pack such that mixed lymphocyte reactions (MLR) are abolished whilst satisfactory platelet function is retained during subsequent storage using Fenwal PL-1240 containers. We have now studied both platelet structure and function after irradiation in DuPont Stericell bags which are both UV-permeable and biocompatible. The irradiation dosage was 3000 Joules/m2 of UVL at a mean wavelength of 310 nm; a dose previously shown to abolish MLR. No detriment to platelet function was observed when compared to control as measured by aggregation responses to adenosine diphosphate (ADP), collagen and ristocetin, hypotonic shock response and pH during 5 d of storage. Lactate levels were significantly higher (P less than 0.01) and glucose levels lower (P less than 0.01) in UV-treated PC, although in the majority the lactate level did not exceed 20 mmol/l. Betathromboglobulin and platelet factor 4 levels were higher during storage in the UV group, the latter reaching significance (P less than 0.05). When whole platelets and platelet membranes were stained with Coomassie blue or Periodic Acid-Schiff's reagent after electrophoresis in polyacrylamide gels no obvious alterations to major membrane constituents were observed on days 1 and 5 of storage. Paired in vivo autologous studies in healthy volunteers using 111Indium-labelling were performed at the end of 5 d of storage. The UV-treated platelets gave satisfactory and equivalent results for recovery, half life and survival when compared to controls. We conclude that PC irradiated with UVL and stored for 5 d in DuPont Stericell containers appear suitable for transfusion and may prove to be nonimmunogenic. Further in vivo studies of haemostatic efficacy and recipient alloimmunization are now warranted.     

Post-transfusion recovery of function of 5-day stored platelet concentrates

Summary Platelets show a rapid reduction in their responsiveness to aggregating agents during storage for transfusion, but little is known about reversal of this defect in vivo after transfusion. In this study, fresh and stored platelets from the same donor ( n =12) were labelled with ¹¹¹In or ⁵¹Cr, respectively, mixed, and simultaneously infused. Blood samples were taken for up to 5 d post-infusion, and the functional behaviour of the labelled platelets ex vivo was measured by retention on glass bead columns, and by whole blood aggregability to ADP, epinephrine and ristocetin. Aggregation was determined by filtering aggregated samples through a column of cotton wool to remove the aggregates, and quantitated as per cent decrease in radioactive counts. The study showed that, although infused radiolabelled 5 d stored platelets had a significantly lower aggregability towards ADP and epinephrine immediately (1 h) after infusion (32% and 29%, respectively, of fresh platelet values), a complete restoration to fresh platelet levels was found 24–72 h post-infusion, with no further change observed over the ensuing 5 d with either fresh or stored labelled platelets. A slightly (6–9%) lower adhesion to both uncoated and collagen-coated beads was found for the stored platelets throughout the 5 d period of study post-infusion.
In conclusion, these studies show that, with ex vivo testing, platelets stored for 5 d quickly recovered adhesion and aggregability capabilities similar to that of fresh platelets, suggesting that the functional lesion developed during storage is quickly and completely reversed after infusion.     

Preparation of Leucocyte-Poor Platelet Concentrates from Buffy Coats

To study survival and function of leukocyte-poor platelet concentrates (lp-PC) prepared from buffy coats, random platelet transfusions requested for thrombocytopenic patients were evaluated. The lp-PC issued were stored at 22 degrees C for either 1, 3 or 5 days before transfusion. From 31 transfusions, posttransfusion corrected count increments (CCI), corrected for body surface (m2) and divided by number of platelets transfused (1011), were calculated. The mean +/- SEM of the 1-, 24- and 48- hour CCI was 12.2 +/- 0.45, 11.2 +/- 0.51 and 8.8 +/- 0.58, respectively. No significant differences in CCI 24 h after transfusion were observed for 1p-PC stored for 1, 3 or 5 days. Hemostatic activity was observed in all 9 evaluable patients. It is concluded that platelets from 1p-PC survive well in patients, regardless of storage for 1, 3 or 5 days and that the platelets are hemostatically active after transfusion.     

The Effect of Clinical Prostacyclin Infusions in Advanced Arterial Disease on Platelet Function and Plasma 6-keto PGF1α Levels

S ummary . We have infused synthetic prostacyclin (PGI₂) continuously for approximately 72 h at the maximum tolerated dose (ranging from 5 to 60 ng/kg/min) into nine patients with advanced arterial disease. Prior to the infusion seven out of nine patients had spontaneous platelet aggregation and five out of six patients tested had an abnormal circulating platelet aggregate ratio. During the infusion only one patient still had spontaneous aggregation and all the abnormal circulating platelet aggregate ratios returned to the normal range. However, none of the patients showed any suppression of ADP induced aggregation. The level of exogenous PGI₂ required in vitro prior to the infusion to completely inhibit ADP induced aggregation was 5–10 ng/ml in three of the four patients tested. Ten healthy adults showed complete inhibition with 1 ng/ml of PGI₂. It appears that the platelets of some patients with arterial disease are more resistant to the anti-aggregating properties of PGI₂.     

A randomized study of buffy coat platelets in platelet additive solution stored 1–5 versus 6–7 days prior to prophylactic transfusion of allogeneic haematopoietic progenitor cell transplant recipients

Background and Objective  Storage of platelets > 5 days provides improved availability, logistical management and decreased outdating. Promising results on in vitro parameters and on in vivo post-transfusion recovery and survival of autologous platelets in healthy volunteers have earlier been shown. To provide additional verification, randomized patient transfusion studies are needed.
Materials and Methods  Sixty allogeneic haematopoietic progenitor cell transplant recipients were randomized to receive buffy-coat (BC) platelets stored in platelet additive solution (PAS) for 1–5 days the first time a prophylactic transfusion was needed after transplantation, followed the second time by platelets stored for 6–7 days or vice versa. The corrected count increment (CCI) for 1 and 24 h were calculated.
Results  CCI 1 h and CCI 24 h were higher for platelets stored 1–5 days as compared to 6–7 days, 10·4 ± 5·1 vs. 7·4 ± 3·8 ( P <  0·001) and 5·4 ± 4·1 vs. 2·6 ± 2·6 ( P <  0·001), respectively. Time to next platelet transfusion was significantly longer after a transfusion of platelets stored for 1–5 days as compared to platelets stored for 6–7 days: 2·2 ± 1·1 vs. 1·6 ± 0·8 days, respectively ( P <  0·005). No differences in bleeding events and no transfusion reaction were recorded.
Conclusion  The advantage of an extension of platelet storage time beyond day 5 should be balanced against the increased need for platelet transfusions that may occur and the conceivable risk of transfusion failure.     

A multicenter randomized study of the efficacy of transfusions with platelets stored in platelet additive solution II versus plasma

Randomized studies testing the clinical efficacy of platelet additive solutions (PASs) for storage of platelets are scarce and often biased by patient selection. We conducted a multicenter, randomized study to investigate clinical efficacy of platelets stored in PAS II versus plasma, also including patients with clinical complications associated with increased platelet consumption. A total of 168 evaluable patients received pooled buffy coat-derived platelet concentrates (PCs) suspended in either plasma (n = 354) or PAS II (n = 411) stored up to 5 days. Both univariate as well as multivariate analysis showed a significant effect of used storage medium in regard to 1- and 24-hour count increments and corrected count increments, in favor of plasma PCs. However, there were no significant differences between the groups regarding bleeding complications and transfusion interval. Adverse transfusion reactions occurred significantly less after transfusions with PAS II PCs (P = .04). Multivariate analysis showed no significant effect of the used storage medium on the incidence of 1- and 24-hour transfusion failure. We showed safety and efficacy of PAS II PCs in intensively treated patients; however, plasma PCs show superior increments.     

Comparison of posttransfusion recoveries achieved with either fresh or stored platelet concentrates

Summary The effectiveness of platelet concentrate transfusion depends on such variables as blood bag material, donor — recipient compatibility, and time elapsed between donation and transfusion. To study the latter a corrected thrombocyte increment for recovery in the recipients was evaluated with 108 platelet transfusions in 31 patients. In 83 treatment programs, the mean recovery at the one-hour post-transfusion time point was 8.6×10⁹ platelets/l with fresh platelets and 5.9×10⁹ platelets/l with stored platelets. Significantly better recovery was achieved with freshly prepared platelet over the total of platelet concentrates stored for up to 96 hours; however, if the recoveries in different patient groups given stored platelets were considered separately in terms of storage times of up to 48 h or 48–96 h, the good recovery with fresh platelets was significantly better only when compared to the older (p=0.034) but not to the younger group of stored platelets. In patients with signs indicating enhanced platelet destruction (fever, splenomegaly, disseminated intravascular coagulation) the transfusion with fresh platelet concentrates gave a significantly better recovery compared to stored platelet concentrates (p=0.028), whereas in the absence of such signs the recovery produced by fresh concentrates was not significantly higher than with stored concentrates. These findings may be relevant for the logistics in blood banking.     

Assessment of the hemostatic effectiveness of human platelets treated with aminomethyltrimethyl psoralen and UV A light using a rabbit ear bleeding time technique

The photochemical aminomethyltrimethyl psoralen (AMT), in conjunction with UV A light (UVA), has been shown to inactivate human immunodeficiency virus-1 and model viruses in platelet suspensions under conditions that have only a minimal effect on in vitro platelet properties. A rabbit ear bleeding time technique was used to assess the hemostatic effectiveness of human platelet suspensions treated with AMT/UVA. New Zealand White rabbits were made thrombocytopenic by a combination of irradiation and heterologous antirabbit platelet antiserum. Reticuloendothelial function in these rabbits was suppressed by the intravenous administration of ethyl palmitate. The hemostatic function of 1- and 5-day-old human platelet suspensions (14.5% plasma) that had been treated on day 1 with 40 micrograms/mL AMT and 24 kJ/m2 UVA (1 x UVA) was evaluated by measuring microvascular bleeding times after a standard incision. Comparable bleeding times were observed after infusion with both control and AMT/UVA-treated platelets stored for either 1 or 5 days. With the transfusion of AMT/1 x UVA-treated platelets stored for 5 days, the mean (+/- SD) bleeding time was 156.3 +/- 39.2 seconds (n = 10). With untreated platelets (no AMT/no UVA), stored for 5 days, the mean bleeding time was 189.2 +/- 36.4 seconds (n = 10). Neither AMT nor 1 x UVA treatment alone influenced the observed bleeding times. In contrast, the hemostatic effectiveness of human platelet suspensions was diminished if they were exposed to three times the standard UVA dose (72 kJ/m2) on day 1 and stored for 4 more days, regardless of whether AMT was present, with the mean bleeding time increasing to 442.2 +/- 122.6 seconds (n = 15, AMT present) or 396.0 +/- 45.9 seconds (n = 10, AMT absent). These results are consistent with data obtained from in vitro studies and indicate that virucidal AMT/1 x UVA treatment does not influence platelet hemostatic function. However, the final conditions to achieve these results must be carefully controlled.     

Effects of Ethanol Administration on Platelet Function in the Rat

When ethanol is administered to rats chronically by inhalation for 5–7 days to produce a final ethanol concentration in plasma of about 50 TTIM platelet agggregation in vitro to collagen is markedly inhibited. Platelet aggregation to ADP is relatively unaffected and there is no evidence of thrombocytopenia or morphological change in platelets on scanning and transmission electron microscopy. The changed sensitivity to collagen is not simply due to the presence of ethanol in plasma during the in vitro tests because in vitro addition of a similar concentration of ethanol produces a much smaller inhibition of platelet aggregation to collagen in platelet-rich plasma from control animals. The acute or subacute administration of ethanol either by injection (3 g/kg^-1 intraperitoneally) or by inhalation (4–6 h) produced very variable results, platelets from some animals being inhibited with respect to collagen as much as those from animals chronically exposed to ethanol, whereas others showed no inhibition other than that attributable to the presence of ethanol in plasma. When ethanol was administered chronically by inhalation for 30 days, thrombocytopenia was apparent and platelets from these animals were unresponsive to all aggregating agents tested. It is concluded that even relatively short periods of ethanol intake may lead to significant inhibition of platelet function, specifically aggregation to collagen. This may be of relevance to the suggested protective effect of ethanol intake in cardiovascular disease.     

Physiologic concentrations of arginine vasopressin activate human platelets in vitro

Arginine vasopressin (AVP) is a neurohypophyseal peptide hormone with protean effects. Previous reports had shown that AVP stimulates platelets, but only at concentrations 3–6 logs higher than the normal plasma concentrations in humans. In this study we tested the hypothesis that AVP, at physiologic concentrations, stimulated the expression of an activation-dependent platelet antigen. Platelets obtained from normal volunteers were incubated with increasing concentrations of AVP and the expression of the activation-dependent platelet antigen P-selectin (CD62) was determined by monoclonal antibodies and flow cytometry. There was a concentration-dependent increase in CD62 expression with increasing AVP concentration; at 1 p m AVP, 24.5% (1.3–88.5%) [median (range)] of platelets expressed CD62. The selective vasopressin V₁ receptor antagonist d(CH₂)₅-Tyr(me)AVP (TM-AVP) completely abolished AVP-stimulated CD62 expression. We conclude that AVP can activate platelets at concentrations found in normal humans, at least in vitro, and that this response is mediated by the platelet V₁ receptor. AVP may be a physiologic platelet agonist.     

Pathogen reduction technology (Mirasol®) treated single-donor platelets resuspended in a mixture of autologous plasma and PAS

Background and Objectives  Mirasol^® pathogen reduction technology (PRT) for platelet concentrates uses riboflavin and ultraviolet light. Previously, we described increased metabolism and activation for PRT platelets stored in 100% plasma. To improve platelet quality, we resuspended platelets in a mixture of plasma and platelet additive solution (PAS).
Materials and Methods  Single-donor platelets were resuspended in plasma and split into an untreated control and a PRT-treated single product. One hundred and fifty millilitre PAS (SSP+) was added to both. Over 7 days, we assayed pH, glucose consumption-, lactate production rate and CD62p with and without TRAP.
Results  On day 5, PRT units showed a significantly lower pH (7·087 ± 0·105 vs. 7·288 ± 0·200) accompanied by a higher lactate production (0·104 ± 0014 vs. 0·063 ± 0·017 mmol/10¹²/h) and glucose consumption rate (0·039 ± 0005 vs. 0·028 ± 0·009 mmol/10¹² platelets/h). CD62p expression was higher in treated units (44·5 ± 13·0 vs. 16·5 ± 7·6%).
Conclusion  In comparison to PRT platelets resuspended in 100% plasma, a mixture of plasma and PAS improves pH and platelet metabolism but not platelet activation. Prolonged shelf-life for up to 7 days may be possible.