Platelet Additive Solution Research Articles

The effects of pathogen reduction technology on apheresis platelet concentrates stored in PAS.

The impact of pathogen reduction technology (PRT) such as Mirasol, and the effect of platelet additive solutions (PAS) on the activity and hemostatic profile of transfused apheresis platelets remain largely unknown. The aim of this study was to assess the in vitro hemostatic and metabolic profile of Mirasol treated platelets in PAS during a 7-day storage period. Ten split bags containing apheresis platelets stored in PAS were split into two groups; control platelets (No.=10 units) and PRT-treated platelets (No.=10 units). In vitro evaluation of the platelet components was performed on the 1st, 3rd, 5th, and 7th days of the storage period. Several metabolic parameters including pH, glucose, and lactate levels were evaluated, while assessment of their hemostatic capacity was performed using light transmission aggregometry (LTA) and viscoelastic studies such as rotational thromboelastometry (ROTEM) and thromboelastography (TEG). Last, Annexin V levels were measured though flow cytometry for evaluation of platelet activation. Clot strength, as reflected by the maximum clot firmness (MCF) and the maximum amplitude (MA) parameters of the viscoelastic studies was significantly decreased in the PRT-treated platelets compared to the control platelets (p<0.05). Clot strength based on MCF and MA values was also found to be decreasing over storage time in PRT-treated platelets (p<0.001), while this was not evident in control platelets. Moreover, the comparison between pH, glucose, and lactate levels were indicative of increased metabolic activity in PRT-treated platelets compared to control platelets (p<0.001). Last, Annexin-V was significantly higher in PRT-treated platelets compared to control platelets on the 7th day of the storage period (p<0.001). The results of this study indicate that increased PSL induced by PRT treatment leads to a decreased in vitro platelet hemostatic efficacy and increased metabolic activity. However, the clinical impact of these alterations needs further investigation.

Genetic engineering of transfusable platelets with mRNA-lipid nanoparticles is compatible with blood banking practices

AbstractPlatelets contribute to a variety of physiological processes, including inflammation, sepsis, and cancer. However, because of their primary role in hemostasis, platelet transfusions are largely restricted to managing thrombocytopenia and bleeding. One way to expand the utility of platelet transfusions would be to genetically engineer donor platelets with new or enhanced functions. We have previously shown that lipid nanoparticles containing mRNA (mRNA-LNP) can be used to genetically modify authentic platelets in a nonclinical crystalloid solution. Currently, platelets collected for transfusion are stored in plasma or in plasma supplemented with platelet additive solution (PAS) at supraphysiological concentrations at room temperature, or at 4°C if intended for use in acute hemorrhage. Here, we describe a new plasma-optimized mRNA-LNP for transfecting platelets directly in plasma and plasma supplemented with PAS that is scalable to physiological and supraphysiological platelet concentrations. Transfecting platelets in clinical solutions with mRNA-LNP does not affect aspects of in vitro physiology, and transfected platelets are storable. The compatibility of this transfection system with current clinical practices could enable future mRNA-LNP–based platelet products and cell therapies.

Delayed cold-stored vs. room temperature stored platelet transfusions in bleeding adult cardiac surgery patients—a randomized multicentre pilot study (PLTS-1)

BackgroundPlatelets stored at 1–6 °C are hypothesized to be more hemostatically active than standard room temperature platelets (RTP) stored at 20–24 °C. Recent studies suggest converting RTP to cold-stored platelets (Delayed Cold-Stored Platelets, DCSP) may be an important way of extending platelet lifespan and increasing platelet supply while also activating and priming platelets for the treatment of acute bleeding. However, there is little clinical trial data supporting the efficacy and safety of DCSP compared to standard RTP.MethodsThis protocol details the design of a multicentre, two-arm, parallel-group, randomized, active-control, blinded, internal pilot trial to be conducted at two cardiac surgery centers in Canada. The study will randomize 50 adult (≥ 18 years old) patients undergoing at least moderately complex cardiac surgery with cardiopulmonary bypass and requiring platelet transfusion to receive either RTP as per standard of care (control group) or DCSP (intervention group). Patients randomized to the intervention group will receive ABO-identical, buffy-coat, pathogen-reduced, platelets in platelet additive solution maintained at 22 °C for up to 4 days then placed at 4 °C for a minimum of 24 h, with expiration at 14 days after collection. The duration of the intervention is from the termination of cardiopulmonary bypass to 24 h after, with a maximum of two doses of DCSP. Thereafter, all patients will receive RTP. The aim of this pilot is to assess the feasibility of a future RCT comparing the hemostatic effectiveness of DCSP to RTP (defined as the total number of allogeneic blood products transfused within 24 h after CPB) as well as safety. Specifically, the feasibility objectives of this pilot study are to determine (1) recruitment of ≥ 15% eligible patients per center per month); (2) appropriate platelet product available for ≥ 90% of patients randomized to the cold-stored platelet group; (3) Adherence to randomization assignment (> 90% of patients administered assigned product).DiscussionDCSP represents a promising logistical solution to address platelet supply shortages and a potentially more efficacious option for the management of active bleeding. No prospective clinical studies on this topic have been conducted. This proposed internal pilot study will assess the feasibility of a larger definitive study.Trial registrationNCT 06147531 (clinicaltrials.gov).

Isohemagglutinin titration in pooled and apheresis platelets.

Platelet inventory constraints necessitate ABO-incompatible platelet transfusion. Many minimize the hemolytic impact by confirming low titre (LT) donor isohemagglutinins. This process is costly. Pathogen-reduced platelets (PRP) in platelet additive solutions (PAS) will dilute plasma and decrease high-titre isohemagglutinins (HT). We determined the proportion of HT platelets and incompatible transfusions for units suspended in plasma to reassess the need for titres following introduction of PRP/PAS. Our titre method is manual tube (1:50) dilution of platelet supernatant from apheresis or whole blood derived buffy coat pools suspended in plasma, tested with A1/B red cells. Testing included 49,058 pooled and 11,738 apheresis platelets over 4 years. The HT proportion, rate of out-of-group transfusions, and hemolytic reactions were determined. The impact of PAS dilution was estimated. Totally 60,796 platelet units were tested. Group O pooled and group B apheresis platelets had HT in 6.6% and 5.7%, respectively. Group A pooled and apheresis platelets included 2% with HT. Approximately 25% of platelets transfused were ABO-incompatible and no hemolytic reactions were reported. Based on the proportions of PAS-E and plasma for PRP platelets, plasma from each donor comprises 11 mL (6% of total volume) vs 20-257 mL in untreated pools. PAS-E will replace and dilute residual plasma by at least 50%. Rare platelet pools may demonstrate HT. PRP platelets with PAS will reduce titres and may abrogate the need for titration. A strategy of group specific transfusion or transfusion of group A PRP platelet transfusions may be a safe alternative.

Comparable bacterial growth in platelet concentrates suspended in plasma and platelet additive solution and improved detection of bacterial contamination using a new generation automated culture system.

Microbial screening of platelet concentrates (PC) with automated culture methods is widely implemented to reduce septic transfusion reactions. Herein, detection of bacterial contamination in PC was compared between units prepared in plasma and a mix of plasma and platelet additive solution (PAS) and between the BACT/ALERT 3D and next generation BACT/ALERT VIRTUO systems. Double apheresis units were split into single units, diluted in either PAS (PAS-PC) or plasma (plasma-PC), and tested for in vitro quality and sterility prior to spiking with ~30 CFU/unit of Staphylococcus epidermidis, Staphylococcus aureus, Serratia marcescens, and Klebsiella pneumoniae or ~10 CFU/mL of Cutibacterium acnes. Spiked PC were sampled for BACT/ALERT testing (36 and 48 h post-spiking) and colony counts (24, 36, and 48 h post-spiking). Times to detection (TtoD) and bacterial loads were compared between PC products and BACT/ALERT systems (N = 3). Bacterial growth was similar in plasma-PC and PAS-PC. No significant differences in TtoD were observed between plasma-PC and PAS-PC at the 36-h sampling time except for S. epidermidis which grew faster in plasma-PC and C. acnes which was detected earlier in PAS-PC (p < .05). Detection of facultative bacteria was 1.3-2.2 h sooner in VIRTUO compared with 3D (p < .05) while TtoD for C. acnes was not significantly different between the two systems. Comparable bacterial detection was observed in plasma-PC and PAS-PC with PC sampling performed at 36-h post blood collection. PC sampling at ≤36 h could result in faster detection of facultative pathogenic organisms with the VIRTUO system and improved PC safety.

Temperature Dependence of Platelet Metabolism.

Temperature plays a fundamental role in biology, influencing cellular function, chemical reaction rates, molecular structures, and interactions. While the temperature dependence of many biochemical reactions is well defined in vitro, the effect of temperature on metabolic function at the network level is poorly understood, and it remains an important challenge in optimizing the storage of cells and tissues at lower temperatures. Here, we used time-course metabolomic data and systems biology approaches to characterize the effects of storage temperature on human platelets (PLTs) in a platelet additive solution. We observed that changes to the metabolome with storage time do not simply scale with temperature but instead display complex temperature dependence, with only a small subset of metabolites following an Arrhenius-type relationship. Investigation of PLT energy metabolism through integration with computational modeling revealed that oxidative metabolism is more sensitive to temperature changes than glycolysis. The increased contribution of glycolysis to ATP turnover at lower temperatures indicates a stronger glycolytic phenotype with decreasing storage temperature. More broadly, these results demonstrate that the temperature dependence of the PLT metabolic network is not uniform, suggesting that efforts to improve the health of stored PLTs could be targeted at specific pathways.

The platelet storage lesion, what are we working for?

Platelet concentrate (PC) transfusions are crucial in prevention and treatment of bleeding in infection, surgery, leukemia, and thrombocytopenia patients. Although the technology for platelet preparation and storage has evolved over the decades, there are still challenges in the demand for platelets in blood banks because the platelet shelf life is limited to 5 days due to bacterial contamination and platelet storage lesions (PSLs) at 20-24°C under constant horizontal agitation. In addition, the relations between some adverse effects of platelet transfusions and PSLs have also been considered. Therefore, understanding the mechanisms of PSLs is conducive to obtaining high quality platelets and facilitating safe and effective platelet transfusions. This review summarizes developments in mechanistic research of PSLs and their relationship with clinical practice, providing insights for future research. Authors conducted a search on PubMed and Web of Science using the professional terms "PSL" and "platelet transfusion." The obtained literature was then roughly categorized based on their research content. Similar studies were grouped into the same sections, and further searches were conducted based on the keywords of each section. Different studies have explored PSLs from various perspectives, including changes in platelet morphology, surface molecules, biological response modifiers (BMRs), metabolism, and proteins and RNA, in an attempt to monitor PSLs and identify intervention targets that could alleviate PSLs. Moreover, novel platelet storage conditions, including platelet additive solutions (PAS) and reconsidered cold storage methods, are explored. There are two approaches to obtaining high-quality platelets. One approach simulates the invivo environment to maintain platelet activity, while the other keeps platelets at a low activity level invitro under low temperatures. Understanding PSLs helps us identify good intervention targets and assess the therapeutic effects of different PSLs stages for different patients.

Indocyanine Green-Labeled Platelets for Survival and Recovery Studies

Plain Language SummaryWe developed a simple, reproducible method according to Good Manufacturing Practice guidelines for labeling of platelets from platelet concentrates (PCs) with indocyanine green (ICG) as a non-radioactive alternative. PCs are medicinal drugs that are transfused to prevent or treat bleeding. They consist of the blood cells’ platelets which are responsible for clotting processes in the body. Manufacturing procedures of PCs are continuously refined, and for in vivo testing, these platelets have to be labeled to track and to distinguish them from proband’s or patient’s own cells. Radioactive labeling, for a long time the gold standard for cell labeling, is no longer accepted. ICG is a fluorescent dye approved by the drug authorities and already used for diagnostic purposes in humans. We used ICG to label platelets from PCs. With our method, we achieved a labeling efficiency of 99.8%. We used whole blood (WB) as an ex vivo matrix to monitor the labeling stability of ICG-labeled platelets. After the addition of ICG-labeled platelets to WB, the labeling efficiency decreased to 81% after 24 h. However, we were still able to distinguish the ICG-labeled platelets from the WB platelets. We could also show that platelet function was not impaired by the labeling processes. The good tolerance of ICG indicates a short path to clinical application in healthy volunteers and investigations of novel PC-manufacturing procedures. As a read-out system, flow cytometry systems equipped with NIR lasers and filters could offer the possibility of rapid visualization, cell tracking, re-isolation, and ex vivo studies.

P‐BB‐17 | Biochemical Parameters at Day 7 of Storage of Pathogen Reduced (UVA/Amotosalen) and Conventional Platelets in Additive Solution With or Without Irradiation

P‐BB‐17 | Biochemical Parameters at Day 7 of Storage of Pathogen Reduced (UVA/Amotosalen) and Conventional Platelets in Additive Solution With or Without Irradiation

P‐TS‐19 | Comparison of Platelet Increment with Conventional Versus Psoralen‐treated Platelets Suspended in Platelet Additive Solution or Plasma

P‐TS‐19 | Comparison of Platelet Increment with Conventional Versus Psoralen‐treated Platelets Suspended in Platelet Additive Solution or Plasma

P‐BB‐20 | Can We Consider Platelets in Platelet Additive Solution as “High‐Titer Negative” for Anti‐A/B?

P‐BB‐20 | Can We Consider Platelets in Platelet Additive Solution as “High‐Titer Negative” for Anti‐A/B?

P‐CB‐6 | Composition of Platelet Additive Solution Impacts Bioenergetic Status of Platelets Following Cold Storage: Role of pH and Fuel Substrates

P‐CB‐6 | Composition of Platelet Additive Solution Impacts Bioenergetic Status of Platelets Following Cold Storage: Role of pH and Fuel Substrates

Nutrient supplementation of culture media improves the detection of Cutibacterium acnes in platelet components by an automated culture system.

Platelet concentrates (PCs) contaminated with Cutibacterium acnes are often transfused prior to detection by the BACT/ALERT system. Though C. acnes is implicated in mild transfusion reactions, delayed clinical effects are unknown. This study assessed the ability to enhance C. acnes detection by supplementing culture media with Tween 80 (T80, an oleic acid source) and a commercial nutrient supplement. Anaerobic culture bottles (BPN) were supplemented with T80 or oleic acid. T80-supplemented BPN bottles were inoculated with four C. acnes isolates (10 or 100 colony-forming units [CFU]/bottle) or other transfusion-relevant bacteria (10 CFU/bottle). Samples of plasma containing SSP+ (platelet additive solution [PAS]) (PAS-plasma) at different concentrations, plasma-PCs and PAS-PCs, spiked with two C. acnes isolates (10 CFU/bottle), were inoculated into T80-supplemented BPN bottles. Furthermore, plasma-PCs were spiked with C. acnes and tested in BPN bottles supplemented with the BD Difco Supplement VX (BDVx). Bottles were incubated in the BACT/ALERT system and times to detection (TtoD) were compared (N = 3). A reduction in TtoD of ≤3.5 days was observed for C. acnes in T80-supplemented BPN, while other species did not show the same effect. However, false positives were observed when T80-supplemented BPN was inoculatedwith PAS-plasma (except for 70% PAS:30% plasma), plasma-PCs or PAS-PCs. Oleic acid supplementation also resulted in false positives. Interestingly, BDVx-supplemented BPN reduced the TtoD of C. acnes in PCs by ≤1.2 days (p < 0.05), with no false-positive results. BDVx supplementation for detection of C. acnes from PCs could result in timely unit retrieval, preventing the transfusion of contaminated products. In clinical settings, T80 supplementation could significantly enhance C. acnes detection from non-blood-derived samples.

Evaluation of Platelet Storage Lesion (PSL) Markers in SSP+ Platelet Additive Solution Added Canine Platelet Concentrates (CPC)

Background: To evaluate the Platelet Storage Lesion (PSL) markers and extended storage time for SSP+ added Canine Platelet Concentrates (CPC) beyond five days at 22°C.Fresh Canine CPCundergo certain metabolic and morphologic changes during storage. Estimation of PSL markers helps us better understand quality of the canine PC and to estimate the efficacy of SSP+ in increasing the life span of stored CPC. Method:CPC was prepared from 350 ml of whole blood, collected from 6 apparently healthy donor dogs by buffy coat methodin a quadruple bag closed system. CPC was divided into four aliquots of 15 ml each with one control and three test groups with SSP+ additive solution in different concentrations (65%, 75%, 85%). TheIn vitro PSL markers including swirling, pH, glucose, lactate, bicarbonate, pO2, pCO2, platelet concentration, MPV and PDWwere evaluated on day 1, 5, 9 and 13 of storage. Result:The results were analysed by Two-way ANOVA wherein swirling, pH, glucose, lactate, bicarbonate, pO2, pCO2, platelet concentration, MPV showed significant difference (p less than 0.01) between the groups. Interaction between the additive concentrations and the days of storage revealed a pH on day 9 for 65% SSP+ to be similar to day 5 for Plasma stored CPC while swirling, lactate and bicarbonate were also better maintained for 65% SSP+ PAS added CPC till day 9.Addition of 65% SSP+ PAS to CPC evidenced increased shelf life up to 9 days at 22°C under agitation without significant deterioration in product quality.

Lipidomic analysis of differently prepared platelet concentrates in additive solution during storage.

Structural and biochemical changes in stored platelets are influenced by collection and processing methods. Lesions may appear during platelet concentrate storage, some of which may be involved in adverse transfusion reactions. The preparation and storage of platelet concentrates (PC) may modify and even damage the lipid mediator content. The aim of this study was to investigate the lipidomic profile identified in the supernatants of PCs according to processing and storage conditions, both after leukocyte filtration and contained in platelet additive solution (PAS), comparing single donor apheresis (SDA) products with pooled buffy coat (BC) products. We investigated the accumulation of various lipid mediators including lysophospholipids (LP) and eicosanoids in SDA and BC products stored for 0-5 days. All products were processed following French Blood Establishment (EFS) procedures in accordance with EDQM/GTS European Standards. Both SDA and BC were leukocyte reduced and conserved in 35% autologous donor plasma and 65% platelet additive solution. Lipidomic analysis was performed on PC supernatants using LS/MS spectrometry. Our data demonstrate that lysophosphatidylcholine (LPC) levels were higher in BCs compared to SDAs, with no difference in lysophosphatidic acid (LPA) expression between the two preparation methods. Results for other eicosanoids showed greater similarity; indeed, no clear pattern emerged from analysis of eicosanoids in terms of storage time and process. In general, we observed longitudinal lipid mediator modulation for both SDAs and BCs, particularly at later time points. The expression of LPC and some eicosanoids in BCs could be used as novel biomarkers of PC quality. Future studies are needed to explore their impact on adverse transfusion reactions.

Evaluation of platelet additive solution for prolonging storage of functional canine platelet concentrate.

To assess storage lesion development, platelet function, and bacterial growth in canine platelet concentrates (PCs) stored in a platelet additive solution (PAS) or a plasma control at 4°C for 21days. Prospective, ex vivo, experimental controlled study. University veterinary teaching hospital. Ten units of canine PCs collected from blood bank donations. The PCs were separated into 2 bags, 1 containing 100% plasma and the other containing 35% plasma and 65% of a PAS (Plasma-Lyte A), and stored at 4°C for 21days. At days 0, 7, 14, and 21, PCs were analyzed for the presence of swirling, aggregate formation, platelet counts, platelet indices, glucose, lactate, lactate dehydrogenase, Pvco2 , Pvo2 , aggregation via light aggregometry, activation percentages using flow cytometry, and bacterial growth. Cold-stored PCs in both PAS and plasma control maintained mean pH >6.8 and mean lactate <9.0mmol/L over 21days, with no difference in glucose utilization. Swirl was maintained in both solutions for most days (76/80 combined total samples), with no difference in aggregate formation between solutions. The Pvco2 was higher in plasma on all days (P<0.001), with no difference in Pvo2 . Platelet indices did not reflect significant storage lesion development in either solution. Lactate dehydrogenase did not differ between solutions but did increase from day 7 to day 21. Mean maximal aggregation percentage was reduced overall but with no significant difference between solutions. The only observed difference in mean activation percentage between solutions was in PAS on day 7, which was significantly higher than plasma (P<0.05). No bacterial growth occurred during storage. Cold storage in PAS and plasma allowed PCs to be stored for up to 21days with minimal storage lesion development, maintenance of platelet function, limited platelet activation, and no bacterial growth within stored bags.

Platelet Additive Solutions as an Alternative Storage Medium of Apheresis Platelets to Reduce ABO Antibody Titer for ABO-Incompatibility Platelet Transfusion.

Introduction Platelet additive solutions (PASs) are nutrient media commonly used to replace and reduce the need for storage plasma. They are an alternative medium to maintain high-quality platelets lasting longer on the shelf for about seven days. Platelets with high titer of ABO antibody can pose a hemolytic transfusion reaction (HTR) risk if units are given across the ABO barrier. The risk of complication is greater when group O platelet is released to non-group O patients. The PAS has been known as a safe medium, where the titer of ABO antibodies is expected to be diluted. In this study, we compared the anti-A and anti-B antibody titers of apheresis platelets in PAS and non-PAS (plasma) as the suspending media. Methods A total of 20apheresis platelet donors were selected, with seven from blood group A, eight from blood group B, and five from blood group O. The platelets were collectedusing an Amicus cell separator. They were suspended in PAS and plasma before being stored at a temperature range of 22-24ºC. Anti-A (blood group B and O)and Anti-B(blood group A and O) antibody titers were measured and compared between the two suspending media. Wilcoxon signed-rank test is used for statistical analysis, and a p-value <0.05 is considered significant. Results The median titer of the anti-A antibody of apheresis platelets showed a significant difference between suspended in PAS (2.50) and plasma (4.00), p=0.002. Similar findings were also seen with the median titer of the anti-B antibody of apheresis platelet, in which it showed a significant difference between suspended in PAS (2.00) and plasma (4.00), p=0.004. It was observed that there was a significant reduction in both anti-A and anti-B antibody titers in the PAS as compared to the plasma group. Conclusion The decrease in ABO antibody titer in apheresis platelets stored with PAS can be beneficial for patients. This reduces the risk of HTRs if ABO-incompatible platelet units need to be issued. Thus, using PAS as a storage medium significantly improves platelet inventory management without compromising patient safety.

Quantitative increases of extracellular vesicles in prolonged cold storage of platelets increases the potential to enhance fibrin clot formation.

Platelet derived extracellular vesicles (EVs) display a pro-coagulant phenotype and are generated throughout platelet concentrate (PC) storage. Cold storage (CS) of PCs is thought to provide a superior haemostatic advantage over room temperature (RT) storage and could prolong the storage time. However, the effect of storage conditions on EV generation and PC function is unknown. We investigated EV production under CS and RT conditions and assessed whether these EVs exhibited a more pro-coagulant phenotype in model experiments. Buffy-coat-derived PCs in a platelet additive solution (PAS) to plasma ratio of approximately 65:35 were stored at RT (22 ± 2°C) or CS (4 ± 2°C) for a prolonged storage duration of 20 days. Impedance aggregometry assessed platelet function. EVs were isolated throughout storage and quantified using nanoparticle tracking analysis. EVs were applied to a coagulation assay to assess the impact on fibrin clot formation and lysis. CS produced significantly larger EVs from day 4 onwards. EV concentration was significantly increased in CS compared to RT from day 15. EVs, regardless of storage, significantly reduced time to clot formation and maximum optical density measured compared to the no EV control. Clot formation was proportionate to the number of EV applied but was not statistically different across storage conditions when corrected for EV number. EVs in CS and RT units showed similar clot formation capacity. However, the higher number of larger EVs generated in CS compared to RT suggests PC units derived from CS conditions may overall exhibit a haemostatically superior capacity compared to RT storage.

Feasibility evaluation of two novel systems for the automated preparation and extended storage of DMSO cryopreserved platelets.

Manufacturing methods for dimethyl sulfoxide (DMSO)-cryopreserved platelets (CPPs) are manual and labor intensive. Thawing and prepare-for-transfusion steps are in an open system that requires transfusion within 4 h. A fill-and-finish system (CUE) can automate the manufacturing process. A newly configured bag system allows freezing, thawing, and use of resuspension solutions while maintaining the functionally closed system, and extending the post-thaw shelf life beyond 4 h. Our objective is to evaluate the feasibility of the CUE system and the functionally closed bag system. DMSO was volumetrically added to double-dose apheresis platelets, concentrated, and delivered to a 50- or 500-mL ethylene-vinyl acetate (EVA) bag by the CUE (n = 12). The functionally closed bag system contained 25 mL platelet additive solution 3 (PAS-3) in a 50-mL EVA bag. Control CPP (n = 2) were manually prepared. PAS-3 and CPP were thawed together. CPP were stored up to 98 h (20-24°C) and tested using a standard assay panel. CUE prepared CPP met the design targets: volume, platelet content, and DMSO concentration. CUE CPP P-selectin was high. CD42b, phosphatidylserine (PS) expression, and live cell percentage were favorable compared to controls and favorably maintained over storage. The thrombin generation potency was slightly reduced compared to controls. The 50 mL EVA bag maintained pH for up to 30 h, and the 500 mL EVA bag beyond 76 h. The CUE system presents a technically feasible method to prepare CPP. A functionally closed bag system with resuspension solution was successful and can extend the post-thaw storage time of CPP.

Two cases of Streptococcus dysgalactiae subspecies equisimilis infection transmitted through transfusion of platelet concentrate derived from separate blood donations by the same donor.

Transfusion-transmitted bacterial infections (TTBIs) in Japan have been largely prevented due to a short shelf life of 3.5 days after blood collection for platelet concentrate (PC) and washed PCs (WPCs; PC in which 95% plasma is replaced by platelet additive solution). Case 1: In January 2018, a woman in her 50s with aplastic anaemia who received WPC transfusion and developed a fever the next day and Streptococcus dysgalactiae subspecies equisimilis (SDSE) was detected in the residual WPC. Case 2: In May 2018, a man in his 60s with a haematologic malignancy who received PC transfusion and developed chills during the transfusion. SDSE was detected in the patient's blood and residual PC. The contaminated platelet products were both manufactured from blood donated by the same donor. The multi-locus sequencing typing revealed that SDSE detected in case 1 was identical to that from case 2; however, whole blood subsequently obtained from the donor was culture negative. WPC and PC produced from two blood donated 106 days apart by the same donor were contaminated with SDSE of the same strain and both caused TTBIs. Safety measures should be considered regarding blood collection from a donor with a history of bacterial contamination.