Frozen and cold-stored platelets: reconsidered platelet products.

Platelet transfusion, both prophylactic and therapeutic, is a key element in modern medicine. Currently, the standard platelet product for clinical use is platelet concentrates at room temperature (20-24°C) under gentle agitation. As this temperature favors bacterial growth, storage is limited to 5-7 days, which result in high wastage rate, and complicates inventory and product availability at remote areas. Frozen and/or cold storage would ameliorate those disadvantages by reducing the risk of bacterial contamination and by extending the product shelf-life to weeks or even years. Consequently, the usefulness in transfusion medicine of platelet cryopreservation and refrigeration, two old and scarcely used platelet storage approaches, is reemerging. Indeed, there have been substantial recent research efforts to characterize both cold and cryopreserved platelets. Most recent studies indicate that cryopreserved and cold platelets display a pro-coagulant profile that may produce the rapid hemostatic response which is needed in bleeding patients. Thus, it seems appropriate that blood banks and blood transfusion centers explore the possibility of split platelet inventories consisting of platelets stored at room temperature and cryopreserved and cold-stored platelets.

Compliance with temperature and time requirements during in-hospital distribution of blood components: A national survey among transfusion services.

INTRODUCTION: Temperature and time conditions during storage and distribution of blood components (BC) and their permissible deviations are strictly regulated. The degree of compliance with these requirements in daily practice of transfusion services (TS) is not well known. MATERIALS AND METHODS: We conducted a survey among Spanish hospital TS covering different aspects of BC management in their daily activity. RESULTS: Eighty-three TS managing 56 % of total transfusions answered the survey. Monitoring of red blood concentrates (RBC) temperature during in-hospital distribution was routinely performed by only 12 % of the TS. The main criterion for BC re-entry into the stock was the total time spent outside controlled temperature. Up to 41 % of the TS apply the "30-minute rule" to distributed RBC, while most services use a 60-minute rule for PC. No adverse events were detected when RBC that had remained longer than 30 or 60 min outside the TS were transfused. Fresh frozen plasma is usually thawed 2 h preissue and stored at 4 °C up to 24 h. DISCUSSION AND CONCLUSIONS: In the Spanish context, the 30- and 60-minute rules for re-entry of RBC and PC into the TS stock are loosely followed. Feedback for a large number of TS suggests that the extension of the 30-minute RBC rule to at least 60 min is feasible, if other safety requirements are met. Flexibility with some requirements could help reduce product loss without deleterious effect on BC safety.

Proteomic analysis of extracellular vesicles derived from platelet concentrates treated with Mirasol® identifies biomarkers of platelet storage lesion.

In blood banks, platelets are stored until 7 days after a pathogen reduction technology (PRT) treatment, Mirasol® (vitamin B2 plus UVB light) in the present case. The storage time under these conditions may have an impact on platelets and their releasate leading to potential adverse reactions following transfusion to patients. The aim of this study was to analyze the proteome of extracellular vesicles generated by platelets at different storage days (2 and 7) to gain deeper information on the platelet concentrates state at those moments. EVs were isolated by a centrifugation-based approach and characterized by dynamic light scattering and transmission electron microscopy. Proteomic analysis was by LC-MS/MS and quantification by SWATH. In this way, 151 proteins were found up-regulated at day 7 of storage. This group includes CCL5 and Platelet Factor 4, chemokines with power to attract neutrophils and monocytes, which could generate transfusion adverse reactions. In addition, other glycoproteins and platelet activation markers were also found elevated at day 7. Proteins related to glycolysis and lactate production were found altered with high fold changes, showing a deregulation of platelet metabolism at day 7. The obtained results provide novel information about possible effects of platelet-derived EVs on transfusion adverse reactions. SIGNIFICANCE: We performed the first proteomic analysis of extracellular vesicles derived from platelets upon storage at different time points on blood bank conditions after Mirasol® treatment. We identified a high number of proteins related to platelet activation and platelet storage lesion that could have a role in possible transfusion adverse reactions.

Assessment of the Clinical Performance of Platelet Concentrates Treated by Pathogen Reduction Technology in Santiago de Compostela.

INTRODUCTION: This study assessed the feasibility, performance, and safety of Mirasol®-treated platelet concentrates (M-PC) stored for up to 7 days. METHODS: This prospective observational study was approved by the ethical committee of the University Clinic of Santiago de Compostela. Informed consent was asked from patients receiving M-PC. M-PCs were treated with the Mirasol system according to the manufacturer's instructions. Thrombocytopenic patients were transfused according to the Spanish transfusion guidelines. Post-transfusion platelet counts were measured at 1 h and/or 24 h after transfusion. Post-transfusion surveillance of patients was maintained during the study. RESULTS: Data from 54 evaluable patients and 135 transfusions were analyzed. The mean age of patients was 58 years. The mean age of M-PC at transfusion was 3.6 days. The mean platelet dose was 3.7 × 1011. The transfusion responses measured as mean corrected count increment 1 h after transfusion (CCI1h) and CCI24h were 9,659 and 4,751, respectively. 65% of transfusions resulted in CCI1h values ≥ 7,500. 51% of transfusions resulted in CCI24h values ≥ 4,500. CONCLUSION: The use of M-PC in the supportive treatment proved to be safe and effective for this cohort of thrombocytopenic patients.

Collection, storage, inspection and quality control of platelet concentrates obtained by apheresis: The situation in Spain.

BACKGROUND: Diverse variables are involved in apheresis platelet collection, processing and storage. This survey shows how these are realized in Spain. METHOD: An analysis of collected data was performed in a questionnaire completed by ten Transfusion Centers (TC) which perform between 50 and 520 apheresis procedures per month. This information comprises the procedures used to collect, inspect and store apheresis platelet concentrates (PC), and quality control data. RESULTS: Macroscopic inspection of PC is performed in all TC, especially during the first few hours post-collection and before distribution. The type of processor, duration of post-collection resting periods and temperature from the time of collection until distribution are similar in all TC. In 80% of TC, PC with small and scarce aggregates are distributed to transfusion services. The presence of clumps is influenced by type of processor, female donor, cold ambient temperature and collection of hyperconcentrated platelets, and is often recurrent in the same donor, although some TC have not found any influential variables. Overall, no objective inspection methods are followed, although there are exceptions. The degree of compliance with quality control parameters, such as the number of units studied, mean platelet yield, residual leukocyte counts and pH at expiry date, is acceptable in all TC. Compliance in terms of number of microbiological culture samples is variable. DISCUSSION: The usual practice in Spanish TC with respect to the collection, post-collection handling and storage of apheresis PC can be considered uniform, although some specific aspects of analyses should follow more objective methods.

In vitro evaluation of platelet concentrates suspended in additive solution and treated for pathogen reduction: effects of clumping formation.

BACKGROUND: Platelet concentrates may demonstrate visual, macroscopic clumps immediately after collection following aphaeresis or production from whole blood, independently of the preparation method or equipment used. The relationship between the occurrence of clumping and their effect on in vitro quality of platelets was investigated. MATERIAL AND METHODS: Platelet concentrates, suspended in SSP+ additive solution (Macopharma), were obtained by automated processing and also from routine processing. A total of twelve units were allocated to the test group (n=12) due to the presence of clumps. Platelet concentrates without clumps were used as controls (n=10). All platelet units were treated for pathogen reduction following storage under continuous agitation for in vitro testing over a 9-day storage period. RESULTS: No significant differences were found throughout storage between the groups. The lactate dehydrogenase levels increased in both groups; this increase was higher in the test group on the last day of testing, without there being a significant difference on day 2. In contrast, pH values on day 2 were significantly different between the test and control groups. Platelet-derived cytokines increased comparably during storage. DISCUSSION: The results confirm good in vitro quality and storage stability of platelets suspended in SSP+ and treated with the Intercept pathogen reduction system. The presence of "non-compacted" clumps in platelet concentrates does not appear to affect the in vitro quality of the platelets.

Treatment of buffy coat platelets in platelet additive solution with the mirasol(®) pathogen reduction technology system.

BACKGROUND: The Mirasol pathogen reduction technology (PRT) system uses riboflavin and ultraviolet light and is currently approved and used in Europe for the treatment of platelets and plasma. Mirasol treatment is intended to reduce the infectious pathogen load and to inactivate leukocytes in blood products. Our objective was to evaluate buffy coat platelet concentrates (BCPCs) prepared with platelet additive solution (PAS) and treated with the Mirasol system and to examine the effects on platelet cell quality during storage. METHODS: 26 BCPCs were prepared and split, creating 13 paired control and test units. The test units were treated with the Mirasol system and the platelet quality was assessed in all units over 7 days of storage. RESULTS: All products met the incoming specifications for Mirasol treatment, and the pH of all Mirasol-treated BCPCs in PAS met the requirements of the Council of Europe guidelines throughout storage. Analysis of lactate production and glucose consumption rates, CD62p expression and cytokines indicates enhanced cellular metabolism in treated platelets, but the levels were within previously published ranges. CONCLUSION: While Mirasol-treated BCPCs in PAS had increased metabolism and activation compared to controls, the results indicate that these units can be stored for 7 days with acceptable cell quality.

Guía sobre la transfusión de componentes sanguíneos / Guide for thransfusion of blood components

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