Platelet Storage Lesion Research Articles

Proteome Changes in Platelets After Pathogen Inactivation—An Interlaboratory Consensus

Pathogen inactivation (PI) of platelet concentrates (PCs) reduces the proliferation/replication of a large range of bacteria, viruses, and parasites as well as residual leucocytes. Pathogen-inactivated PCs were evaluated in various clinical trials showing their efficacy and safety. Today, there is some debate over the hemostatic activity of treated PCs as the overall survival of PI platelets seems to be somewhat reduced, and in vitro measurements have identified some alterations in platelet function. Although the specific lesions resulting from PI of PCs are still not fully understood, proteomic studies have revealed potential damages at the protein level. This review merges the key findings of the proteomic analyses of PCs treated by the Mirasol Pathogen Reduction Technology, the Intercept Blood System, and the Theraflex UV-C system, respectively, and discusses the potential impact on the biological functions of platelets. The complementarities of the applied proteomic approaches allow the coverage of a wide range of proteins and provide a comprehensive overview of PI-mediated protein damage. It emerges that there is a relatively weak impact of PI on the overall proteome of platelets. However, some data show that the different PI treatments lead to an acceleration of platelet storage lesions, which is in agreement with the current model of platelet storage lesion in pathogen-inactivated PCs. Overall, the impact of the PI treatment on the proteome appears to be different among the PI systems. Mirasol impacts adhesion and platelet shape change, whereas Intercept seems to impact proteins of intracellular platelet activation pathways. Theraflex influences platelet shape change and aggregation, but the data reported to date are limited. This information provides the basis to understand the impact of different PI on the molecular mechanisms of platelet function. Moreover, these data may serve as basis for future developments of PI technologies for PCs. Further studies should address the impact of both the PI and the storage duration on platelets in PCs because PI may enable the extension of the shelf life of PCs by reducing the bacterial contamination risk.

Platelet Utilization: A Canadian Blood Services Research and Development Symposium

Considerable progress has been made in recent years in understanding platelet biology and in strengthening the clinical evidence base around platelet transfusion thresholds and appropriate platelet dosing. Platelet alloimmunization rates have also declined. Nevertheless, controversies and uncertainties remain that are relevant to how these products can best be used for the benefit of platelet transfusion recipients. Platelets are unique among the blood products directly derived from whole blood or apheresis donations in requiring storage, with shaking, at ambient temperature. Storage is accordingly constrained between the need to limit the growth of any microbes in the product and the need to minimize losses in platelet function associated with storage. Proteomic and genomic approaches are being applied to the platelet storage lesion. Platelet inventory management is made challenging by these constraints. Although bacterial screening has enhanced the safety of platelet transfusions, pathogen reduction technology may offer further benefits. Continuing clinical investigations are warranted to understand the value of transfusing platelets prophylactically or only in response to bleeding in different patient groups and how best to manage the most grievously injured trauma patients. Patients refractory to platelet transfusions also require expert clinical management. The engineering of platelet substitute products is an active area of research, but considerable hurdles remain before any clinical uses may be contemplated. Roles for platelets in biological areas distinct from hemostasis are also emerging. Platelet utilization is variably affected by all of the above factors, by demographic changes, by new medications, and by new patient care approaches.

An Inhibition of p38 Mitogen Activated Protein Kinase Delays the Platelet Storage Lesion

Background and ObjectivesPlatelets during storage undergo diverse alterations collectively known as the platelet storage lesion, including metabolic, morphological, functional and structural changes. Some changes correlate with activation of p38 mitogen activated protein kinase (p38 MAPK). Another MAPK, extracellular signal-related kinase (ERK), is involved in PLT activation. The aim of this study was to compare the properties of platelets stored in plasma in the presence or absence of p38 and ERK MAPK inhibitors.Materials and MethodsA single Trima apheresis platelet unit (n = 12) was aliquoted into five CLX storage bags. Two aliquots were continuously agitated with or without MAPK inhibitors. Two aliquots were subjected to 48 hours of interruption of agitation with or without MAPK inhibitors. One aliquot contained the same amount of solvent vehicle used to deliver the inhibitor. Platelets were stored at 20–24°C for 7 days and sampled on Days 1, 4, and 7 for 18 in vitro parameters.ResultsInhibition of p38 MAPK by VX-702 leads to better maintenance of all platelet in vitro storage parameters including platelet mitochondrial function. Accelerated by interruption of agitation, the platelet storage lesion of units stored with VX-702 was diminished to that of platelets stored with continuous agitation. Inhibition of ERK MAPK did not ameliorate decrements in any in vitro platelet properties.ConclusionSignaling through p38 MAPK, but not ERK, is associated with platelet deterioration during storage.

Decreasing phosphodiesterase 5A activity contributes to platelet cGMP accumulation during storage of apheresis‐derived platelet concentrates

Platelet storage lesion (PSL) considerably decreases the quality of platelets (PLTs) in concentrates characterized by a loss of signaling responses to agonists and impaired PLT activation, secretion, and aggregation. To understand the role of inhibitory signaling pathways in the mechanism of PSL, the basal state of the cyclic nucleotide (CN)-dependent signaling systems in stored PLTs was investigated. Whole blood samples (WB) and apheresis-derived PLT concentrates (APCs) were obtained from healthy volunteers. Washed PLTs were prepared from WB on Day 0 and from APCs on Days 0, 2, and 5. The basal phosphorylation of the vasodilator-stimulated phosphoprotein (VASP) and phosphodiesterase 5A (PDE5A) levels were quantified by Western blot. CN and PDE5A activity were measured by enzyme-linked immunoassay kits. Fibrinogen binding and aggregation were measured in PLT-rich plasma of WB or APC samples. Unpaired t test was used for statistical analysis. Basal VASP phosphorylation levels were comparable in WB and APCs on Day 0. VASP phosphorylation increased significantly during storage of APCs, more pronounced at Ser(239) than at Ser(157) . Similarly, intracellular cGMP, but not cAMP, concentration continuously increased in stored PLTs, whereas PDE5A levels and activity significantly decreased accompanied by diminished thrombin receptor activator peptide 6-induced fibrinogen binding and aggregation. Storage of APCs leads to intracellular cGMP accumulation that could be caused by degradation of PDE5A. Enhanced cGMP level supports subsequent cGMP-dependent protein kinase-mediated increase of VASP phosphorylation resulting in reduced fibrinogen binding and aggregation.

Evaluation of amotosalem treated platelets over 7 days of storage with an automated cytometry assay panel

Pathogen Inactivation allows to overcome microbial contamination and growth related to storage of platelets concentrates (PC) at room temperature. The aim of our study was to evaluate the platelet storage lesion extending the storage period of pathogen inactivated platelet concentrates over 7days using an automated cytometry assay panel. We analyzed 43 concentrates subjected to pathogen inactivation (CPPI) at 3, 5 and 7days evaluating: platelet count, mean platelet volume, platelets at low optical density, platelets at high density, GPIIb-IIIa glycoprotein, platelet microparticles, lactate dehydrogenase. The collection bags (Fenwal) and the IBS kit made in PL2410/PL2411 are approved for the conservation of PC up to 7days. Data analysis was performed with anova test. All the parameters except small platelets and PMP were statistically different among day 7 vs. 3 and day 7 vs. 5. Our study showed a progressive modification of pathogen inactivated platelet concentrates observed up to 7days. The persistence of the secretory pool and the presence of the platelet membrane fibrinogen receptor suggest the persistence of a potential hemostatic efficacy. Clinical studies are necessary to directly correlate this type of analysis to 24h recovery or survival of transfused platelets in humans.

Impact of glucose and acetate on the characteristics of the platelet storage lesion in platelets suspended in additive solutions with minimal plasma

Glucose and acetate have been proposed to be required elements in platelet storage media. This study investigated the role of these compounds on the varied elements that comprise the platelet storage lesion. For each replicate, four pooled and split ABO group-specific buffy coat-derived platelet concentrates were suspended in an in-house additive solution with minimal plasma and varying final concentrations of acetate or glucose. Units were sampled on days 2, 3, 6, 8 and 10 and tested for markers of platelet morphology, activation, function, metabolism and indicators of cell death. The absence of glucose was associated with a decrease in ATP, falling to a mean of 1·1±0·1μmol/10(11) plts in units with no added glucose compared with 4·2±0·6μmol/10(11) plts (P<0·001) in units with 30mm glucose. As glucose became depleted, the decrease in ATP to levels below 3μmol/10(11) plts was associated with an increase in both annexin V binding and intracellular free calcium. In units lacking exogenous acetate, ATP levels on day 10 were 5·2±1·5μmol/10(11) plts compared with 2·7±0·9μmol/10(11) plts in units with 56mm acetate (P=0·006). Higher concentrations of exogenous acetate were associated with a lower hypotonic shock response and higher surface expression of CD62P suggestive of a dose dependency. Under current physical storage conditions, glucose appears necessary for the maintenance of platelets stored as concentrates in minimal volumes of plasma. The addition of acetate was associated with increased platelet activation and reduced ATP levels.

Proteomic analysis of platelets treated with gamma irradiation versus a commercial photochemical pathogen reduction technology

Several strategies are currently being tested to reduce the risk of pathogen transmission associated with platelet (PLT) transfusion. Within the framework of the Italian Platelet Technology Assessment Study, we investigated the variations of the protein profiles (proteomics) of apheresis PLT concentrates (PCs) upon treatment with riboflavin and ultraviolet (UV) light (Mirasol; 6.24 J/mL; 280-400 nm). Control, gamma-irradiated, and Mirasol-treated apheresis PCs were assayed on Days 1 and 5 of storage by means of gel-based analytical approaches (two-dimensional gel electrophoresis) and mass spectrometry-based identification of significant (p < 0.05 analysis of variance) differential proteins. Supernatants were then assayed for metabolism and oxidative stress-related metabolites through multiple reaction monitoring mass spectrometry. Only a handful of modifications could be observed in the PLT proteome profiles in response to the Mirasol treatment, which included proteins involved in oxidative stress responses, PLT metabolism, and activation. Results confirmed increased metabolic rate and oxidative stress in the supernatants of treated PLTs (both gamma irradiated and Mirasol treated). From this investigation, it emerges that, from a proteomics standpoint, gamma irradiation results in the acceleration of PLT storage lesions and the Mirasol treatment only moderately exacerbates these phenomena.

Stored platelets alter glycerophospholipid and sphingolipid species, which are differentially transferred to newly released extracellular vesicles

Stored platelet concentrates (PLCs) for transfusion develop a platelet storage lesion (PSL), resulting in decreased platelet (PLT) viability and function. The processes leading to PSL have not been described in detail and no data describe molecular changes occurring in all three components of stored PLCs: PLTs, PLC extracellular vesicles (PLC-EVs), and plasma. Fifty PLCs from healthy individuals were stored under standard blood banking conditions for 5 days. Changes in cholesterol, glycerophospholipid, and sphingolipid species were analyzed in PLTs, PLC-EVs, and plasma by mass spectrometry and metabolic labeling. Immunoblots were performed to compare PLT and PLC-EV protein expression. During 5 days, PLTs transferred glycerophospholipids, cholesterol, and sphingolipids to newly formed PLC-EVs, which increased corresponding lipids by 30%. Stored PLTs significantly increased ceramide (Cer; +53%) and decreased sphingosine-1-phosphate (-53%), shifting sphingolipid metabolism toward Cer. In contrast, plasma accumulated minor sphingolipids. Compared to PLTs, fresh PLC-EVs were enriched in lysophosphatidic acid (60-fold) and during storage showed significant increases in cholesterol, sphingomyelin, dihydrosphingomyelin, plasmalogen, and lysophosphatidylcholine species, as well as accumulation of apolipoproteins A-I, E, and J/clusterin. This is the first detailed analysis of lipid species in all PLC components during PLC storage, which might reflect mechanisms active during in vivo PLT senescence. Stored PLTs reduce minor sphingolipids and shift sphingolipid metabolism toward Cer, whereas in the plasma fraction minor sphingolipids increase. The composition of PLC-EVs resembles that of lipid rafts and confirms their role as carriers of bioactive molecules and master regulators in vascular disease.

Early storage lesions in apheresis platelets are induced by the activation of the integrin αIIbβ3 and focal adhesion signaling pathways

Production and storage of platelet concentrates (PC) induce protein changes in platelets leading to impaired platelet function. This study aimed to identify signaling pathways involved in the development of early platelet storage lesions in apheresis-PCs stored in plasma or additive solution (PAS). Apheresis-PCs from four donors were stored in plasma or in PAS at 22°C (n=4 each). Platelets were analyzed at day 0 (production day) and after 1, 6 and 9 days of storage. Platelet response to agonists (TRAP, collagen, ADP) and to hypotonic shock decreased, CD62P expression increased in both storage media over time. Using DIGE 1550 protein spots were monitored and compared to baseline values at day 0. Platelets in plasma displayed changes in 352 spots (166/day 1, 263/day 6 and 201/day 9); in PAS 325 spots changed (202/day 1, 221/day 6, 200/day 9). LC-ESI-MS/MS analysis of 405 platelet proteins revealed 32 proteins changed during storage in plasma (9/day 1, 15/day 6 and 26/day 9) and 28 in PAS (5/day 1, 20/day 6, 26/day 9). Ingenuity pathway analysis found integrin-αII(b)β(3) and focal adhesion signaling pathways involved in early alterations, being confirmed by Western blotting. Corresponding mRNAs in platelets were identified by next generation sequencing for 84 changed proteins. Integrin-αII(b)β(3) and focal adhesion signaling cause irreversible early storage lesions in apheresis platelets. This article is part of a Special Issue entitled: Integrated omics.

Shaking hands with the future through omics application in transfusion medicine and clinical biochemistry.

Shaking hands with the future through omics application in transfusion medicine and clinical biochemistry.

Characteristics of the THERAFLEX UV-Platelets pathogen inactivation system – An update

Considerable progress has been made in the last decade in producing purer, safer, leucocyte and plasma reduced platelet concentrates (PC) with an extended shelf life. The development of different pathogen inactivation technologies (PIT) has made a substantial contribution to this trend. Preceding platelet PIT (INTERCEPT Blood System/Cerus Corporation, Concord, CA, USA; MIRASOL/Caridian BCT, Lakewood, CO, USA) are based on adding a photosensitive compound to PC. The mixture is then activated by UV light in the UVB and/or UVA spectral regions. A novel procedure, THERAFLEX UV-Platelets (MacoPharma, Mouvaux, France), was recently developed that uses short-wave ultraviolet light (UVC), without addition of any photoactive agent. This technology has proven to be highly effective in sterilising bacteria (the major cause of morbidity/mortality after platelet transfusion) as well as inactivating other transfusion transmitted DNA/RNA containing pathogens and residual leucocytes.Any PIT reflects a balance between the efficacy of pathogen inactivation and preservation of platelet quality and function. A broad spectrum of in vitro tests have become available for the assessment of platelet storage lesion (PSL), aiming to better predict clinical outcome and untoward effects of platelet therapy. Recent paired studies on the release of platelet-derived cytokines, as new platelet performance indicators, revealed a parallel increase in both THERAFLEX UV-treated and control PC throughout storage, supporting the notion that the bioavailability of platelet function is not grossly affected by UVC treatment. This is corroborated by some newer technologies for proteomic analysis, showing that the THERAFLEX UV-Platelets system results in limited disruption of integrin-regulating extracellular disulfide bonds and minimal protein alterations when compared to UVB and gamma irradiation. Moreover, standard in vitro parameters reflecting activation, metabolic activity and function of platelets are useful indicators of the overall performance of processing and storage and may be used as surrogate markers of platelet quality in vivo. However, there is some doubt as to what degree each marker alone or in combination reflects the true clinical outcome of transfused platelets. Therefore, an appropriate clinical programme has been initiated. The preclinical evaluation demonstrated tolerability and immunological safety of THERAFLEX UV-Platelets using an animal model. Additionally, the system has successfully completed two autologous Phase I trials on recovery and survival. Preliminary results suggest that the recovery and survival rates are consistent with other pathogen reduced platelet products that are licensed and in use. The method is currently under evaluation for safety and tolerability of UVC-treated platelets in healthy volunteers. Presently the THERAFLEX UV-Platelets system is the simplest and purest PIT easily adaptable to the existing blood bank setting. In the future, extension of the application range of the THERAFLEX UV-Platelets system is expected, in order to make this new technology compatible with a broad spectrum of collection and processing platforms, and with other blood products.

Current status of additive solutions for platelets

The storage of platelets in additive solution (PAS) had lagged behind red cell concentrates, especially in North America. The partial or complete removal of anticoagulated plasma and storage of platelet concentrates in AS presents many advantages. The PAS can be formulated to optimize aerobic metabolism or decrease platelet activation, thus abrogating the platelet storage lesion and potentially improving in vivo viability. Plasma removal has been shown to reduce allergic reactions and the plasma harvested could contribute to the available plasma pool for transfusion or fractionation. PAS coupled to pathogen reduction technology results in a platelet product of equivalent hemostatic efficacy to conventionally stored platelets. Given the above, the likely future direction of platelet storage will be in new generation designer PAS with an extended shelf life and a superior safety profile to plasma stored platelets. J. Clin. Apheresis, 2012. © 2012 Wiley Periodicals, Inc.

Immunomodulatory Mediators in Platelet Transfusion Reactions

Our appreciation of the roles that platelets play in vascular biology is constantly expanding. One of the major roles of platelets is in initiating and accelerating immune responses. Platelet transfusion may be associated with adverse inflammatory outcomes manifested as fever, discomfort, tachycardia, and respiratory issues. This may in part be due to immune mediators either expressed by activated platelets or released into the platelet media during platelet storage. This review will highlight some more recent knowledge gained regarding the platelet storage lesion and potential mediators of platelet transfusion reactions.

Kindlin-3 Undergoes Endoproteolysis in Stored Platelets and After Platelet Stimulation

Abstract 1255Kindlins are a family of FERM domain proteins that are essential for inside-out integrin activation. In particular, kindlin-3 is required for the conversion of the major platelet integrin αIIbβ3 from its resting conformation to its active ligand binding conformation. Moreover, naturally-occurring kindlin-3 mutations result in the inherited disorder leukocyte adhesion deficiency III, one component of which is defective platelet function that mimics Glanzmann thrombasthenia. Despite the importance of kindlin-3 in initiating αIIbβ3 function in platelets, little is known about its regulation in resting platelets or its fate in activated platelets. To address these questions, we purified full-length kindlin-3 from outdated human platelets where it is present in substantial amounts and also developed a procedure to synthesize substantial amounts of recombinant kindlin-3 in SF9 cells. We found that in stored human platelets, kindlin-3 is cleaved into two fragments as a function of the time of storage. We also found that kindlin-3 is cleaved into identical fragments when fresh human platelets are stimulated with the thrombin receptor activating peptide (TRAP) for 5 minutes. To identify the site of kindlin-3 cleavage, as well as the responsible protease, we used a proteomics method in which an engineered peptide ligase, subtiligase, was used to selectively biotinylate the unblocked α amines of proteins obtained from platelet lysates (Mahrus et al, Cell 134:866–76, 2008). Biotinylated proteins were digested with trypsin and the resulting biotinylated peptide fragments were then captured using avidin agarose and identified using tandem mass spectrometry. Using this method, we identified the kindlin-3 peptide (G)SAPTDVLDSLTTIPELKDHL in lysates of stored platelets, thereby mapping the cleavage site to residues 335–336. We obtained identical results using proteins isolated from TRAP-stimulated platelets. Further, we were able to recapitulate these results in vitro using purified kindlin-3 and the calcium-activated protease calpain, implying that calpain is the responsible protease in vivo. Kindlin-3 is thought to initiate αIIbβ3 function by binding to the distal NITY motif in the β3 cytosolic tail in an interaction that also involves S752. Previously, we reported a model for αIIbβ3 regulation based on an NMR structure of the β3 cytosolic tail (Metcalf et al, PNAS 107:24775–83, 2010). In this structure, the NITY motif is located in a distal dynamic amphiphilic helix where the motif is transiently masked by interacting with the membrane. To validate this model, we have studied the interaction of both purified and recombinant kindlin-3 with the β3 tail using surface plasmon resonance (SPR). A peptide corresponding to β3 residues 719–762, encompassing the complete β3 tail, was immobilized on a CM5 chip and kindlin-3 was flowed over the chip surface. The resulting sensorgrams could then be fit to two binding events with dissociation constants of 2.2 nM and 2.8 μM. The biphasic behavior could have resulted from heterogeneity of the β3 tail on the chip surface or heterogeneity of the interaction between kindlin-3 and the carboxymethylated dextran. Similar SPR experiments measuring binding of the talin-1 FERM domain to the β3 tail also could be fit to two binding events with dissociation constants of 155 nM and 3.5 μM. Thus, under these experimental conditions, kindlin-3 binds approximately 70-fold more tightly to the β3 tail than does the talin-1 FERM domain. In summary, these studies demonstrate that kindlin-3 undergoes calpain-mediated endoproteolysis during platelet storage, an event that may contribute to the development of the platelet storage lesion. Kindlin-3 also undergoes an identical cleavage following platelet stimulation by agonists such as thrombin. Since high affinity binding of kindlin-3 to the β3 cytosolic tail is required for physiologic αIIbβ3 activation, it is possible that kindlin-3 cleavage attenuates αIIbβ3 activity. Disclosures:No relevant conflicts of interest to declare.

In vitro quality of single‐donor platelets treated with riboflavin and ultraviolet light and stored in platelet storage medium for up to 8 days

The Mirasol pathogen reduction technology system is known to increase the activation and metabolic rate of platelets (PLTs). Storage of Mirasol PLTs in PLT storage medium (PSM) has the potential to slow this accelerated PLT storage lesion. We investigated the quality of Mirasol-treated PLTs stored in either 50% SSP+ or 50% Composol for 8 days. Single-donor double hyperconcentrates were divided between control and Mirasol-treated arms and after treatment were suspended in approximately 50% (vol/vol) SSP+ (n = 8) or Composol (n = 7). In vitro markers of PLT activation and/or apoptosis were measured over an 8-day storage period. Mirasol treatment resulted in increased spontaneous PLT activation and glycolysis and these effects were worsened when PLTs were treated below a certain volume (150 mL). At higher treatment volumes there were no significant differences between treated units stored in either Composol or SSP+. When low-volume units were stored in Composol the median pH fell below 6.4 on Day 5 and bicarbonate was undetectable, whereas in SSP+ the median pH value was greater than 6.9 and bicarbonate remained at detectable levels, despite other markers of in vitro function being similar to those of Composol. Mirasol treatment of PLTs followed by storage in PSM results in increased PLT activation and metabolism to a level similar to that reported for PLTs treated and stored in plasma. Units treated at a low volume (<150 mL) showed poor in vitro quality.

Determination of thromboxane formation, soluble CD40L release and thrombopoietin clearance in apheresis platelet concentrates

All deleterious changes in platelet morphology, structure and function that occur in platelet concentrates (PC) during storage are titled as the ‘platelet storage lesion’. No single in vitro test currently available is sufficient in assessing these changes of platelet quality. The release of soluble CD40 Ligand (sCD40L), the formation of thromboxane (TXB2) and the thrombopoietin (TPO) clearance reflect different aspects of platelet metabolism and activitiy, and were used to examine platelet quality in apheresis platelet products. At days 1, 3 and 5, in single-donor apheresis platelet products (n = 10) under routine storage conditions, sCD40L (measured by ELISA) and TXB2 (measured by RIA) were determined after platelet stimulation (recalcification and clot formation). TPO (measured by ELISA) was determined after an incubation time of 5 h at 37°C with platelet-rich plasma (adjusted initial TPO concentration of about 500 pg/mL). Results were related to a therapeutic unit (TU = 2 × 1011 platelets). Immediately after platelet preparation, sCD40L release was 41 ± 7.6 ng/TU, TXB2 formation 1688 ± 374 ng/TU and TPO clearance 1.22 ± 0.32 ng/h/TU. At days 1, 3 and 5, sCD40L was reduced to 89 ± 7%, 71 ± 12% and 57 ± 9%, TXB2 release to 91 ± 6%, 74 ± 12% and 58 ± 9% and TPO clearance to 90 ± 15%, 84 ± 5% and 79 ± 10% of the respective control values. In conclusion, in single-donor apheresis PC, sCD40L release and TXB2 formation as well as TPO clearance by the platelets were dependent on storage duration and reduced to about 60% to 80% of the respective control values after a storage period for 5 days. These findings are in line with literature data, indicating that a loss of platelet functionality of about 30% will occur after 5 days of storage.

Statement of Retraction: Gupta A, Chandra T, Kumar A. “Platelet storage lesion: Current proteomics approach”

Statement of Retraction: Gupta A, Chandra T, Kumar A. “Platelet storage lesion: Current proteomics approach”

Overview on platelet preservation: Better controls over storage lesion

Platelet storage lesion (PSL), correlating with reduced in vivo recovery/survival and hemostatic capacity after transfusion, is characterized essentially by morphological and molecular evidence of platelet activation and energy consumption in the medium. Processes that limit shelf-life are multifactorial, and include both necrosis and apoptosis. PSL is greatly influenced by factors including duration of storage, temperature, ratio of platelet number to media volume, solution composition with respect to energy content and buffering capacity, and gas permeability of the container. Recent progress for slowing PSL has been made with storage media that more effectively fuel ATP production and buffer the inevitable effects of metabolism. Improved oxygen-permeability of containers also helps to maintain aerobic-dominant glycolysis. Patients stand to benefit from platelet products of higher intrinsic quality that store well until the moment of transfusion.

The effect of pathogen reduction technology (Mirasol) on platelet quality when treated in additive solution with low plasma carryover

Pathogen reduction technologies (PRT) for platelets are now compatible with both plasma and platelet additive solutions (PAS). The aim of this study was to examine the effect of PRT on the platelet storage lesion, in the presence of PAS with low plasma carryover. PRT-treated (Mirasol) and untreated buffy coat-derived platelet concentrates prepared in 28% plasma/PAS-IIIM were evaluated using in vitro cell quality parameters on days 1, 2, 5, and 7 post-collection. At day 5, there were no significant differences between control and PRT treated platelets for swirl, viability, pO(2) , pCO(2) , mean platelet volume and adenosine diphosphate-induced aggregation. PRT treatment did not affect the functional integrity of the mitochondria. However, PRT resulted in a decrease in pH and enhancement of platelet glycolysis and activation, evidenced by increased glucose consumption and lactate production rates, increased expression of CD62P, CD63, annexin V staining and increased secretion of cytokines (P < 0.05). Hypotonic shock response and aggregation in response to collagen were also significantly reduced in PRT treated platelets (P < 0.05). Despite the observed differences in platelet metabolism and activation observed following PRT treatment in PAS and low plasma carryover, the results suggest that treatment and storage of platelets in PAS is no more detrimental to platelets than treatment and storage in plasma.

In vitro storage characteristics of platelet concentrates suspended in 70% SSP+TM additive solution versus plasma over a 14‐day storage period

The non-paired two-arm study compared the in vitro storage characteristics of platelets suspended as concentrates in either 100% plasma or a mixture of additive solution (SSP+™, MacoPharma, Mouveaux, France) and autologous plasma in a 70:30 ratio over a 14-day storage period. The buffy coat-derived pooled platelet concentrates were sampled on days 1, 2, 3, 6, 8, 10 and 14 and tests performed to determine platelet morphology, function, metabolism, activation and apoptosis-like activity. Swirling remained strong (score=3) in SSP+™, whilst scores of 1 and 0 were noted for plasma units by end of storage. In contrast to units in plasma, pH levels remained above seven in SSP+™ units, increasing after day 10. Percent positive expression of CD62P was similar in both groups on day 1 (median of 54% and 56% for plasma (n=13) and SSP+™ (n=12), respectively), with SSP+™ units showing a more moderate increase in activation after day 10. A progressive decrease in mitochondrial membrane potential was evident in both groups from day 1, whilst annexin V binding was relatively stable from days 1 to 3, with median values remaining below 6%. Subsequent to this, the percentage of platelets binding annexin V increased to approximately 30% by day 14. Platelets suspended in a medium of 70:30 SSP+™ to plasma ratio performed at least as well as platelets in 100% autologous plasma for up to 10 days of storage. Further, results are suggestive of an apoptosis-like process being involved in the platelet storage lesion.