Buffy-coat-derived platelet concentrates prepared from half-strength citrate CPD and CPD whole-blood units. Comparison between three additive solutions: in vitro studies

Platelet storage: Progress so far

There is a crucial need for platelet transfusion during an emergency-surgery and treatment of platelet disorders. The unavailability of donors has furthermore increased the demand for platelet storage. Platelets have limited shelf life due to bacterial contamination and storage lesions. Temperature, materials, oxygen availability, media, platelet processing and manufacturing methods influence the platelet quality and viability during storage. The conception of various platelet additive solutions along with the advent of plastic storage during the 1980s led to enormous developments in platelet storage strategies. Cold storage of platelets gained attention despite its inability to contribute to platelet survival post-transfusion as it offers faster haemostasis. Several developments in platelet storage strategies over the years have improved the quality and shelf-life of stored platelets. Despite the progress, the efficacy of platelets during storage beyond a week has not been achieved. Antioxidants as additives have been explored in platelet storage and have proven to enhance the efficacy of platelets during prolonged storage. However, the molecular interactions of antioxidants in platelets can provide a better understanding of their mechanism of action. Optimization of dosage concentrations of antioxidants is also a critical parameter to be considered as they tend to exhibit toxicity at certain levels. This review provides comprehensive insights into the critical factors affecting platelet storage and the evolution of platelet storage. It also emphasizes the role of antioxidants as additives in platelet storage solutions and their future prospects towards better platelet banking.

Metabolomic analysis of platelets during storage: a comparison between apheresis- and buffy coat-derived platelet concentrates

BACKGROUND

Platelet concentrates (PCs) can be prepared using three methods: platelet (PLT)-rich plasma, apheresis, and buffy coat. The aim of this study was to obtain a comprehensive data set that describes metabolism of buffy coat-derived PLTs during storage and to compare it with a previously published parallel data set obtained for apheresis-derived PLTs.

STUDY DESIGN AND METHODS

During storage we measured more than 150 variables in 8 PLT units, prepared by the buffy coat method. Samples were collected at seven different time points resulting in a data set containing more than 8000 measurements. This data set was obtained by combining a series of standard quality control assays to monitor the quality of stored PLTs and a deep coverage metabolomics study using liquid chromatography coupled with mass spectrometry.

RESULTS

Stored PLTs showed a distinct metabolic transition occurring 4 days after their collection. The transition was evident in PLT produced by both production methods. Apheresis-derived PLTs showed a clearer phenotype of PLT activation during early days of storage. The activated phenotype of apheresis PLTs was accompanied by a higher metabolic activity, especially related to glycolysis and the tricarboxylic acid cycle. Moreover, the extent of the activation differed between bags resulting in interbag variability in the storage lesion of apheresis-prepared PLTs. This may be related to donor-related polymorphism.

CONCLUSION

This study demonstrated two discrete metabolic phenotypes in stored PLTs prepared with both apheresis and buffy coat methods. PLT activation occurs during the first metabolic phenotype and might lead to a low reproducibility of the apheresis PCs.

The role of bicarbonate in platelet additive solution for apheresis platelet concentrates stored with low residual plasma

BACKGROUND

Complex platelet additive solutions (PASs) are required to store platelet (PLT) concentrates with plasma levels below 30%. Previously, apheresis PLTs stored with 5% plasma in acetate- and bicarbonate-containing PAS maintained stable pH and bicarbonate levels during 7-day storage. Due to this observation, the necessity of added bicarbonate in PAS was investigated and whether the concurrent increase in PAS pH after bicarbonate addition had any effect on PLT storage.

STUDY DESIGN AND METHODS

Apheresis PLTs were stored in 5% plasma-95% high- or low-pH PAS, with or without bicarbonate (n=10 per arm). Bicarbonate PAS PLTs were paired and nonbicarbonate PAS PLTs were paired (split from same double-dose collection). PLTs were evaluated for in vitro variables on Days 1 and 7 and up to Day 14 if the Day 7 pH was higher than 6.2.

RESULTS

PLT pH was maintained above 7.3 to Day 14 in bicarbonate PAS PLTs while pH failures below 6.2 were observed in 4 of 10 and 2 of 10 units on Day 7 in low- and high-pH nonbicarbonate PAS arms, respectively. Day 7 in vitro variables in nonbicarbonate PAS PLTs with pH values of higher than 6.2 were comparable to Day 7 variables in bicarbonate PAS PLTs. The pH of bicarbonate PAS did have a small effect on pH and bicarbonate levels in PLT units, but did not have an effect on functional variables and metabolism.

CONCLUSION

Bicarbonate was not required to maintain in vitro PLT function in 5% plasma-95% PAS, but was required as a pH buffer and increased PAS pH did not significantly contribute to this effect.

Precise pH measuring of platelet concentrates containing additive solution--the impact of the temperature

BACKGROUND AND OBJECTIVES

  Blood gas analysers measuring pH at 37°C (pH37) are widely used for pH determination of platelet (PLT) concentrates (PCs). For reporting pH at 22°C (pH22), converting of pH37 using the correct conversion factor is mandatory. For PCs stored in PLT additive solution (PAS), such conversion factors are not yet widely available. We studied pH in samples of PCs with different PAS/plasma ratios during warming from 22 to 37°C.

MATERIALS AND METHODS

  We measured pH in 39 samples containing modified PAS-III (PAS-IIIM) with a plasma carryover of 20%, 30% or 40% or no PAS-IIIM. Differences between pH22 and pH37 (dpH) were compared within and between study groups. Correlation between pH22 and dpH was tested. Additional measurements in 33 samples with three different PLT counts were performed to study the influence of PLT count on dpH.

RESULTS

  pH22 and pH37 within each group and dpH or dpH/dT between study groups differed significantly. The dpH was 0·135 ± 0·040, 0·021 ± 0·009, 0·033 ± 0·011 and 0·048 ± 0·017 for samples containing 100%, 20%, 30% or 40% plasma, respectively. Correlation between dpH and pH22 was strong in 100% (r = 0·696, P < 0·001), weaker in 30% and 40% (r = 0·367, P = 0·022 and r = 0·345, P = 0·032, respectively) and not existing in 20% plasma (r = 0·153, P = 0·354). PLT count did not influence the dpH significantly.

CONCLUSION

  The dpH is dependent on different PAS-IIIM/plasma ratios and pH range. For precise reporting of pH22, the respective dpH must be used if converting is necessary. Preferably, the pH should be reported at 37°C or measured directly at 22°C.

Preparation, storage and quality control of platelet concentrates

Patients with thrombocytopaenia need transfusions of platelet concentrates to prevent or stop bleeding. A platelet transfusion should provide platelets with good functionality. The quality of platelet concentrates (PCs) is affected by the preparation method and the storage conditions including duration of storage, type of storage container, and storage solution (plasma or an additive solution). Different in vivo and in vitro techniques can be used to analyse PCs. Platelets can be collected by apheresis technique, and from whole blood using either the buffy-coat or the platelet-rich plasma method. PCs can be gamma irradiated to prevent occurrence of graft-versus-host disease in the recipient. Pathogen inactivation procedures have been developed to prevent transmission of bacteraemia.

Extracellular accumulation of bioactive substances during preparation and storage of various platelet concentrates

BACKGROUND

Side effects of platelet transfusion may be associated with infusion of bioactive substances. We therefore studied extracellular accumulation of histamine, plasminogen activator inhibitor (PAI)-1, vascular endothelial growth factor (VEGF), and interleukin (IL)-6 during preparation and storage of various platelet concentrates.

METHODS

Twenty buffy-coat-derived platelet pools (BCPC) were prepared and stored in platelet additive solutions (PAS). Twelve apheresis platelet (APC) units were prepared using the COBE Spectra LRS, and 14 were prepared using the Fenwal Amicus Separator. After preparation half of the content was drawn from each APC unit. The normal ranges of the substances were determined in plasma from all donors, and the extracellular concentrations of the substances were determined in supernatants collected on days 0, 1, 3, 5, and 7 of storage from all platelet preparations.

RESULTS

The platelet counts were not significantly different in BCPC units and APC units. The BCPC units had a significantly higher white cell count than the APC units (P < 0.0001), but the count was significantly higher in the Amicus APC units than in the COBE APC units (P < 0.0001). The extracellular histamine concentration was significantly (P < 0.001) increased in BCPC units after preparation and without further increase during storage, while there was no accumulation of histamine in APC units. After preparation the PAI-1 concentration was significantly (P < 0.02) higher in BCPC units than in APC units, but during storage PAI-1 increased significantly (P < 0.05) more in APC units than in BCPC units. Similarly, VEGF concentration was significantly (P < 0.05) higher in BCPC units than in APC units after preparation. During storage, however, VEGF increased more in BCPC units compared with COBE Spectra APC units (P < 0.05), but compared with Amicus Separator APC units only for the first 3 days of storage. At days 5 and 7 of storage the VEGF concentration was significantly higher in the Amicus APC units than in the COBE APC units (P < 0.05). IL-6 was not detectable in any of the concentrates after preparation or during storage.

CONCLUSION

Platelet concentrates prepared by the apheresis method may contain less white cell derived bioactive substances than platelet concentrates prepared by the buffy-coat method. However, a substantial storage time dependent platelet derived bioactive substance accumulation takes place in all platelet concentrates tested, presumably due to platelet disintegration.

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.

A system for the supply of platelets suspended in a storage medium including buffy-coat-derived platelet concentrates in combination with "split" apheresis platelets

Our objective was to create a system for the supply of platelet concentrates (PCs) based on leukocyte-filtered PCs suspended in a storage medium (PAS-II) including: (1) pooled buffy-coat-derived (BC) PCs and (2) "split" apheresis PCs. The same standards were intended for the two preparations with regard to composition and blood cell counts. In preliminary studies, similar in vitro data were found for leukocyte-filtered and non-filtered reference BC PCs. Slightly inferior in vitro results than for BC PCs restricted the shelf-life of apheresis PCs to 5 days compared to 7 days for BC PCs. With the present platelet supply system in use as a routine service for one year, the experience was very satisfactory, meeting the demands for PCs very efficiently and resulting in a low out-dating rate (5%).