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Background and Objectives: Previous studies with p38MAPK inhibitors at room temperature demonstrated that they improve a large number of platelet storage parameters, but cannot substantially inhibit p38MAPK activation nor protect against widespread decrements in platelet quality parameters during 4 °C storage. In this study, platelet quality parameters and inhibition of p38MAPK by VX-702 were studied after incubation of platelets at 16 °C without agitation, suboptimal storage conditions which produce moderate platelet decrements., Materials and Methods: Trima apheresis units were collected and aliquoted into three 60-ml CLX storage bags: (i) a control aliquot which was held at 20-24 °C with constant agitation; (ii) a test aliquot which was held at 20-24 °C with agitation until Day 2, when it was reincubated at 16 ± 1 °C for 24 ± 0·5 h without agitation and then returned 20-24 °C with agitation; (iii) a test aliquot containing 1 μm VX-702 stored in an identical fashion as aliquot 2. Aliquots were tested for an array of platelet storage parameters and p38MAPK activation on Days 1, 4 and 7., Results: Many platelet storage parameters and p38MAPK activation were adversely affected by 24-h incubation at 16 °C without agitation. With the exception of ESC, addition of VX-702 prevented p38MAPK activation and the decrements in most observed parameters., Conclusion: Unlike 4 °C storage, VX-702 prevents activation of p38MAPK and decrements in many platelet storage parameters after exposure to 16 °C without agitation for 24 h., (© 2014 International Society of Blood Transfusion.)

Background: Bacterial sepsis is still a complication in patients transfused with stored platelets (PLTs). We have recently demonstrated that selected antimicrobial peptides (AMPs) have bactericidal activity in bacteria-spiked PLTs. In a subsequent preclinical study, we have also shown that these AMPs do not elicit antibody response in rabbits and treatment of PLTs before transfusion does not affect their in vivo recovery and survival in severe combined immunodeficient mice. Here we have selected two such AMPs, Arg-Trp (RW) repeats of tri- and tetra-peptides (RW3 and RW4) in combination (i.e., cocktail), and evaluated their effect on the in vitro properties of PLTs., Study Design and Methods: Leukoreduced ABO- and D-identical whole blood-derived PLT concentrates were pooled and divided into two 60-mL aliquots in CLX storage bags. On Day 0, one bag received a peptide cocktail of RW3 plus RW4 at 0.01 mmol/L final concentration (test) and the other bag received only phosphate-buffered saline (PBS), the AMP solvent (control). The treated PLTs were stored for 7 days at 20 to 24°C. Samples were collected on Days 1, 5, and 7 to evaluate the in vitro properties of PLTs with standard assays., Results: In vitro properties of the RW3 plus RW4 cocktail-treated PLTs were similar to those incubated with PBS only. There were no significant differences between the control and test PLTs during the 7-day storage., Conclusion: Leukoreduced whole blood-derived PLTs treated with a mixture of RW3 and RW4 peptides maintain their in vitro properties during 7 days of storage., (Published 2014. This article is a U.S. Government work and is in the public domain in the USA.)

Background: Nitric oxide (NO), a potent signaling molecule, is known to inhibit platelet (PLT) function in vivo. We investigated how the levels of NO and its metabolites change during routine PLT storage. We also tested whether the material of PLT storage containers affects nitrite content since many plastic materials are known to contain and release nitrite., Study Design and Methods: For nitrite and nitrate measurement, leukoreduced apheresis PLTs and concurrent plasma (CP) were collected from healthy donors using a cell separator. Sixty-milliliter aliquots of PLT or CP were stored in CLX or PL120 Teflon containers at 20 to 24°C with agitation and daily samples were processed to yield PLT pellet and supernatant. In a separate experiment, PLTs were stored in PL120 Teflon to measure NO generation using electron paramagnetic resonance (EPR)., Results: Nitrite level increased markedly in both PLT supernatant and CP stored in CLX containers at a rate of 58 and 31 nmol/L/day, respectively. However, there was a decrease in nitrite level in PLTs stored in PL120 Teflon containers. Nitrite was found to leach from CLX containers and this appears to compensate for nitrite consumption in these preparations. Nitrate level did not significantly change during storage., Conclusion: PLTs stored at 20 to 24°C maintain measurable levels of nitrite and nitrate. The nitrite decline in nonleachable Teflon containers in contrast to increases in CLX containers that leach nitrite suggests that it is consumed by PLTs, residual white blood cells, or red blood cells. These results suggest NO-related metabolic changes occur in PLT units during storage., (© 2012 American Association of Blood Banks.)

Background: A previous study demonstrated that several in vitro storage properties of apheresis platelets (PLTs) that are isolated by sedimentation against the collection container and subsequently resuspended can benefit from a rest period before continuous agitation. This study examines whether the in vitro storage properties of apheresis PLTs isolated by collection from the buffy coat layer benefit from a rest period before agitation., Study Design and Methods: Freshly collected apheresis PLTs (Trima, GambroBCT) were divided into five 60-mL aliquots. One aliquot was immediately placed on a flat-bed agitator; the other aliquots were held on a laboratory bench for 1, 2, 4, and 6 hours before continuous agitation. Samples were obtained on Days 1, 5, and 7 for standard in vitro PLT assays. The experiment was repeated 12 times., Results: For each sampling day, no significant differences were observed in aliquots held with or without a rest period for any of the following PLT properties: PLT content, mean PLT volume, pH, pCO2, bicarbonate, glucose, lactate, hypotonic shock response, extent of shape change, aggregation, morphology, CD62P, CD63, and CD42b. Although regression analysis identified several in vitro properties whose mean levels appeared to improve with increasing length of the rest period, maximum differences in mean levels were small (<6%)., Conclusion: The in vitro storage properties of Trima apheresis PLTs isolated from the buffy coat layer do not benefit from a rest period., (© 2012 American Association of Blood Banks.)

Background: A comparative study evaluated the retention of apheresis platelet (A-PLT) in vitro properties prepared with PLT additive solution (PAS)-III or 100% plasma and stored with continuous agitation (CA) and without continuous agitation (WCA)., Study Design and Methods: PLTs collected with the Amicus cell separator (Fenwal, Inc.) were utilized to prepare two matched components, each with approximately 4 × 10(11) PLTs. In the primary study, one component contained 65% PAS-III/35% plasma and the other 100% plasma. Four storage scenarios were used, one with CA and three with periods without agitation under simulated shipping conditions. In vitro assays were used early and after 5 days of storage., Results: pH levels after 5 days with CA were less with PAS-III components than 100% plasma components, with levels always above 6.6 in any component. With CA, a number of other variables were reduced even early during storage with PAS-III including morphology, extent of shape change, hypotonic stress response, adhesion, and aggregation. Storage WCA resulted in only a limited increase in the magnitude of the assay differences between PAS-III and 100% plasma components. Periods WCA did not reduce the pH below 6.6. The thromboelastograph variable associated with the strengthening of clots by PLTs was essentially comparable with PAS-III and plasma components throughout storage with CA or WCA., Conclusion: The data indicate that a 100% plasma medium provides for better retention of specific in vitro PLT properties, with CA and WCA, although the clinical significance of these in vitro decrements due to PAS-III is unknown., (© 2011 American Association of Blood Banks.)

Background: Amicus apheresis platelets (PLTs) can be collected using either a single- (SN) or a double-needle (DN) procedure. To investigate whether the method of PLT collection using the same instrument influences PLT quality, the in vitro storage properties of Amicus PLTs were evaluated in the same donors collected by SN and DN procedures., Study Design and Methods: Single apheresis PLT collections with concurrent plasma were performed on donors using the Amicus with a target yield of 4 × 10(11). A PLT unit was collected from a donor assigned to either a SN or a DN procedure; a subsequent donation from the same individual was collected by the other procedure (n = 10). Units were stored at 20 to 24°C with continuous agitation, assayed for 19 PLT storage variables, and analyzed by paired t test, with differences between values obtained with SN and DN collections considered significant with p values of less than 0.001., Results: PLT units collected by SN procedure had contents and concentrations similar to those collected by DN procedures (4.1 × 10(11) ± 0.3 × 10(11) vs. 4.0 × 10(11) ± 0.3 × 10(11) and 1396 × 10(9) ± 131 × 10(9) vs. 1367 × 10(9) ± 110 × 10(9) PLTs/L). On Day 7, SN and DN PLTs had comparable pH values (7.07 ± 0.09 vs. 6.99 ± 0.17), morphology (52.4 ± 18.7% vs. 56.0 ± 13.3% discoid), aggregation (87.1 ± 11.5% vs. 91.3 ± 5.4%), and activation (45. ± 11.9% vs. 48.2 ± 8.7% CD62P), as well as all other variables (p > 0.05; Day 7 CO(2) , p = 0.0304)., Conclusion: The in vitro storage properties of apheresis PLTs collected from the same donors using a SN and DN procedure with the Amicus instrument were maintained through 7 days of storage and yielded comparable results., (© 2011 American Association of Blood Banks.)

Background: pH measurements of platelet (PLT) components remain a key parameter when assessing how storage and shipping conditions influence the retention of PLT properties. Studies were conducted to characterize variations in pH measured with two pH meters and a blood gas analyzer., Study Design and Methods: Samples were obtained from apheresis PLT units that were stored with or without continuous agitation to measure a range of pH values. pH values were determined with pH meters at room temperature (20-24°C) upon placing of samples in 5-mL sterile polypropylene tubes and with the blood gas analyzer at 37°C upon injection of identical samples, with conversion to 22°C., Results: The calculated coefficient of variation (%CV) of pH measurements using pH meters (n = 10) was 0.43% or less. The %CV values were comparable with different samples having pH values ranging from 6.0 to 7.4. The %CV levels with the blood gas analyzer were comparable to those observed with the pH meters. The difference in the mean pH values for the two pH meters was no greater than 0.10 units, with 9 of 10 samples having differences in values of 0.05 or less; however, greater differences of values (0.1 to 0.2) were observed between pH measured using the blood gas analyzer and pH meters., Conclusion: Our data show good precision and comparability of pH measurements with two pH meters. Differences in pH values were greater on comparison of the blood gas analyzer with the pH meters., (© 2011 American Association of Blood Banks.)

We have previously conducted studies investigating maintenance of apheresis platelet in vitro quality measures during storage under simulated shipping conditions in which agitation was interrupted. This study examines the effect of increasing bag surface area on the preservation of in vitro platelet properties during storage with continuous agitation and with a 30 h interruption of agitation. Apheresis platelets were collected in 100% plasma with the Amicus separator to provide two identical platelet products, each with approximately 4-5 x 10(11) platelets. After collection, the volume was divided equally between 1.0 and 1.3 L PL2410 containers. In an initial study, both products were continuously agitated. In a second study, both products were subjected to a single 30-h period of interrupted agitation between Days 2 and 3 of storage by placement in a standard shipping box at room temperature. In each study, units were assayed during storage for standard in vitro platelet quality measures. Platelets stored in the 1.3 L container maintained slightly greater mean pH during 7 day storage with either continuous agitation (n=6) or with a 30-h interruption of agitation (n=12) than those of similarly treated identical platelets stored in the 1.0 L container. Most noteworthy, in experiments with products stored in the 1.0 L container in which there was a large decrease in pH to levels <6.7 or <6.3 on days 5 or 7, respectively, the pH in the matched product stored in the 1.3 L container was substantially greater (0.17+/-06 and 0.37+/-0.09 pH units greater, n=4, respectively). Other measures showed either small differences or comparability of platelet in vitro parameters with storage in the two containers after an interruption of agitation., ((c) 2010 Elsevier Ltd. All rights reserved.)

Background: Many platelet (PLT) components undergo multiple periods of shipment before transfusion. We have previously conducted studies investigating maintenance of apheresis PLT in vitro quality measures during a single 24- or 30-hour interruption of agitation, but data are not available for multiple periods without agitation., Study Design and Methods: Apheresis PLTs were collected with both the Amicus (Fenwal, Inc.) and the Trima (Gambro BCT) cell separators to provide two identical PLT products, each with approximately 4 x 10(11) to 5 x 10(11) PLTs. One product was subjected to a single contiguous 24- or 30-hour period of interrupted agitation between Days 2 and 3 of storage by placement in a standard shipping box at room temperature. The matched product was not agitated on each of 3 days (Days 0, 1, and 3) for specified intervals totaling an identical period of time., Results: Interrupting agitation for three periods resulted in greater maintenance of pH during storage than that observed using one contiguous period. These differences were significant for units held without agitation for 24 hours (Day 5, 0.08 pH units, p < 0.0001; Day 7, 0.10 pH units, p = 0.0059) and were also significant for units held without agitation for 30 hours (Day 5, 0.15, p < 0.0001; Day 7, 0.20, p < 0.0001). The two different interruption of agitation scenarios did not result in significant differences in the extent of shape change and hypotonic shock response variables after 5 or 7 days of storage., Conclusion: Apheresis PLTs subjected to three periods without agitation maintained overall pH levels slightly greater than those of matched units subjected to one contiguous period without agitation. Other measures showed comparability of PLT in vitro variables with the two scenarios for interruption of agitation.

Background and Objectives Previous studies with p38 MAPK inhibitors at room temperature demonstrated that they improve a large number of platelet storage parameters, but cannot substantially inhibit p38 MAPK activation nor protect against widespread decrements in platelet quality parameters during 4 °C storage. In this study, platelet quality parameters and inhibition of p38 MAPK by VX-702 were studied after incubation of platelets at 16 °C without agitation, suboptimal storage conditions which produce moderate platelet decrements. Materials and Methods Trima apheresis units were collected and aliquoted into three 60-ml CLX storage bags: (i) a control aliquot which was held at 20-24 °C with constant agitation; (ii) a test aliquot which was held at 20-24 °C with agitation until Day 2, when it was reincubated at 16 ± 1 °C for 24 ± 0·5 h without agitation and then returned 20-24 °C with agitation; (iii) a test aliquot containing 1 μm VX-702 stored in an identical fashion as aliquot 2. Aliquots were tested for an array of platelet storage parameters and p38 MAPK activation on Days 1, 4 and 7. Results Many platelet storage parameters and p38 MAPK activation were adversely affected by 24-h incubation at 16 °C without agitation. With the exception of ESC, addition of VX-702 prevented p38 MAPK activation and the decrements in most observed parameters. Conclusion Unlike 4 °C storage, VX-702 prevents activation of p38 MAPK and decrements in many platelet storage parameters after exposure to 16 °C without agitation for 24 h. [ABSTRACT FROM AUTHOR]