Variation of pH-measurement in platelet concentrates

To measure pH in platelet concentrates, blood gas analysers with different calibration principles may be used. In this study, variances observed in pH measurements with two types of blood gas analysers were investigated. pH was measured in crystalloid solutions (platelet additive solution (PAS-II), phosphate-buffered solutions) and two types of platelet concentrates (containing 100% plasma, or 65% PAS-II/35% plasma) with two blood gas analysers: either using liquid and gas calibration (AVL 945), or only liquid calibration (AVL OMNI). These measurements were compared with a reference method. Especially for PAS-II, large variation in pH was observed between AVL 945, AVL OMNI and the reference method: 6.91 +/- 0.02, 7.35 +/- 0.02 and 7.188 +/- 0.010, respectively (mean +/- SD; n = 12, P < 0.0001, paired t-test). A significant difference in pH was also found for platelet concentrates in 65% PAS/35% plasma (6.88 +/- 0.09 on AVL 945 and 7.02 +/- 0.09 on AVL OMNI, n = 134, P < 0.0001). Comparison with the reference method revealed minor differences with AVL 945, whereas AVL OMNI gave a mean difference in pH of + 0.17. Platelets in 100% plasma revealed smaller differences (6.93 +/- 0.13 for AVL 945 and 6.99 +/- 0.13 for AVL OMNI, n = 95, P < 0.0001). We conclude that different blood gas analysers can yield different pH values, especially in weak buffered solutions such as platelet concentrates in PAS-II. Validation of blood gas analysers for pH measurement of these solutions is therefore mandatory.     

WBC-reduced platelet concentrates from pooled buffy coats in additive solution: an evaluation of in vitro and in vivo measures

BACKGROUND: The use of a platelet additive solution (PAS-II, Baxter) may have benefits over plasma for storage of platelets. It was the aim of this study to develop a method to produce WBC-reduced platelet concentrates (PCs) in PAS-II with >240 x 10(9) platelets and <1 x 10(6) WBCs per unit, which can be stored for 5 days at pH >6.8 and that will give sufficient platelet increments after transfusion: a 1-hour CCI of >7.5 and a 20-hour CCI of >2.5. STUDY DESIGN AND METHODS: PCs were made from five pooled buffy coats and 250 g of PAS-II. After centrifugation the PCs were WBC-reduced with a filter (Autostop BC, Pall Biomedical) and stored in a 1000-mL polyolefin container. CCIs were assessed in stable hemato-oncologic patients after 5-day old PCs were transfused. RESULTS: Routinely produced PCs contained a median of 310 x 10(9) platelets (n = 5,363) with 3.5 percent containing <240 x 10(9) platelets, in a median volume of 320 mL (n = 11,834). The median number of WBCs was <0.03 x 10(6) (n = 694). The WBC count exceeded 1 x 10(6) in three PCs, but it was always <5 x 10(6), giving 99-percent confidence that more than 99.5 percent of the units will contain <1 x 10(6) WBCs. The pH remained >6.8 on Day 8, provided the concentration was below 1.1 x 10(9) platelets per mL (n = 32). After 28 transfusions in 28 patients, the 1-hour CCI was 12.6 +/- 4.3 (mean +/- SD, with 2/28 CCIs <7.5) and the 20-hour CCI was 8.9 +/- 5.6 (with 4/28 CCIs <2.5). Limitations of this study include the absence of a control group of patients receiving platelets stored in plasma and of in vivo radiolabeled survival studies, but a comparison of these data with previously published data suggested that the in vivo survival of platelets stored in PAS-II is less than that of platelets stored in plasma. CONCLUSION: The WBC-reduced PCs conformed to specifications. These WBC-reduced PCs could be stored at least 5 days with maintenance of pH, and they gave sufficient increments after transfusion to patients.     

医用电解质溶液作添加液制备汇集少白细胞血小板

目的采用医用电解质溶液作添加液(PAS),建立1种白膜法制备添加液汇集少白细胞血小板(PAS汇集BC-PCs)的方法。方法从400ml全血中分离白膜层,容量35—40ml,放(22±2)℃静置过夜,将ABO同型的6袋白膜汇集,加220g添加液(90%复方电解质注射液、8%ACD-A血液保养液和2%含量为50g/L的碳酸氢钠注射液的混合液)稀释白膜,汇集后的白膜在(22±2)℃中,以300×g离心10min,将上层的富含血小板悬液再经白细胞滤除器过滤去除白细胞,并转移到血小板保存袋内,即制备成1个成人治疗量的PAS汇集BC-PCs,制备过程在一个特制的密闭系统内完成。结果共制备30个成人治疗量的PAS汇集BC-PCs,其容量为(270±32)ml、血小板含量为(2.96±0.31)×1011、WBC混入量为(1.3±0.2)×106、RBC混入量为(5.8±1.1)×109、CD62P表达率为(22.5±10.6)%。保存8d后的pH为7.14±0.04、低渗休克反应率(HSR)为(54.0±8.2)%、CD62P表达率为(45.7±13.8)%。结论由复方电解质注射液、ACD-A保养液和碳酸氢钠注射液的混合液为添加液汇集血小板的方法可行。     

Impedance aggregometric analysis of platelet function of apheresis platelet concentrates as a function of storage time

Multiple electrode (impedance) aggregometry (MEA) allows reliable monitoring of platelet function in whole blood. The aims of the present study were to implement MEA for analyzing aggregation in platelet concentrates and to correlate results with storage time and blood gas analysis (BGA). We investigated the influence of platelet counts, calcium concentrations and agonists on platelet aggregation. Samples of apheresis concentrates up to an age of 12 days were investigated by MEA and BGA. For ASPI- and TRAPtest MEA was reproducible for a platelet count of 400 per 10^?9?L and a calcium concentration of 5?mmol L^?1. Platelets at the age of 2–4 days yielded steady aggregation. Platelet concentrates exceeding the storage time for transfusion showed steady aggregation up to 10 days, but a significant decline on day 12. Weak correlation was found regarding pCO₂ and MEA as well as regarding glucose concentration and MEA. Our results indicate that MEA is applicable for evaluation of aggregation in stored apheresis concentrates. Prolonged storage seems not to be prejudicial regarding platelet aggregation. Platelet concentrates showed acceptable BGA throughout storage time. Further studies are required to evaluate the application of MEA for quality controls in platelet concentrates.     

Washing platelets with new additive solutions: aspects on the in vitro quality after 48 hours of storage

BACKGROUND: Rare clinical conditions cause the need for washed platelet (PLT) concentrates (PCs). Saline-washed PCs can only be stored shortly, however, owing to lack of substrates for PLT metabolism. New PLT additive solutions (PASs) contain such substrates and might be used alternatively. The in vitro quality of apheresis PCs washed with Composol-PS or modified PAS-III (PAS-IIIM) stored up to 48 hours after wash was compared. STUDY DESIGN and METHODS: Twelve blood donors underwent two apheresis procedures (A and B) collecting 6.0 x 10(11) PLTs in 500 mL of plasma with a least 2 weeks in between. The PCs collected by Apheresis A were stored for 3 days and then split in two equal units before washing with Composol-PS or PAS-IIIM. The PCs collected by Apheresis B were split after collection. One unit was released for transfusion and 1 unit was stored unwashed up to Day 6 and used as reference unit. In vitro testing was performed before and after washing as well as 24 and 48 hours after wash. RESULTS: After 48 hours of postwash storage, the units washed with either PAS showed acceptable results for hypotonic shock response (HSR), P-selectin expression, and pH, whereas PLT aggregability was significantly impaired. Throughout the storage, unwashed units showed better in vitro quality. HSR and P-selectin expression were similar before and immediately after the washing procedure. CONCLUSION: Based on these in vitro results, 48-hour postwash storage of washed PCs with the two PASs seems to be feasible. In vivo recovery studies, however, must confirm this finding in the future.     

Platelet storage lesion in interim platelet unit concentrates: A comparison with buffy-coat and apheresis concentrates

Platelet storage lesion is characterized by morphological changes and impaired platelet function. The collection method and storage medium may influence the magnitude of the storage lesion. The aim of this study was to compare the newly introduced interim platelet unit (IPU) platelet concentrates (PCs) (additive solution SSP+, 40% residual plasma content) with the more established buffy-coat PCs (SSP, 20% residual plasma content) and apheresis PCs (autologous plasma) in terms of platelet storage lesions. Thirty PCs (n = 10 for each type) were assessed by measuring metabolic parameters (lactate, glucose, and pH), platelet activation markers, and in vitro platelet aggregability on days 1, 4, and 7 after donation. The expression of platelet activation markers CD62p (P-selectin), CD63 (LAMP-3), and phosphatidylserine was measured using flow cytometry and in vitro aggregability was measured with multiple electrode aggregometry. Higher platelet activation and lower in vitro aggregability was observed in IPU than in buffy-coat PCs on day 1 after donation. In contrast, metabolic parameters, expression of platelet activation markers, and in vitro aggregability were better maintained in IPU than in buffy-coat PCs at the end of the storage period. Compared to apheresis PCs, IPU PCs had higher expression of activation markers and lower in vitro aggregability throughout storage. In conclusion, the results indicate that there are significant differences in platelet storage lesions between IPU, buffy-coat, and apheresis PCs. The quality of IPU PCs appears to be at least comparable to buffy-coat preparations. Further studies are required to distinguish the effect of the preparation methods from storage conditions.     

Feasibility study on donor apheresis red cell and platelet simultaneous collection for blood center routine use.

This study was conducted to determine if single donor platelet and red cell simultaneous collection by apheresis technique can be applied to routine blood product collection at blood centers. Both apheresis red cell product and platelet product were successfully collected and mannitol, adenine, and phosphate (MAP) additive solution was added to the red cell concentrates during collection. During a 49 day storage study period, the red cell product quality was maintained and found to be equivalent to that of red cell products derived from whole blood collected by the traditional method. This study demonstrated the possibility of applying this collection method for routine use for single donor apheresis platelet product and red cell product preparation at blood centers.     

Endogenous glutathione and platelet function in platelet concentrates stored in plasma or platelet additive solution

Platelet function was studied in platelet concentrates by assay of the thrombin-induced release of endogenous serotonin and presence of the swirling phenomenon in relation to endogenous glutathione (GSH) and cysteine. In platelets stored in plasma, addition of cysteamine resulted in only a moderate fall in GSH after 5 days of storage, from an average of 14.91 to 11.46 nmol per 109 platelets. Exogenously added GSH had no effect, and addition of buthionine sulfoximine (BSO) resulted in almost complete depletion of GSH, to an average of 0.65 nmol per 109 platelets. Addition of cysteamine or GSH resulted in increased endogenous cysteine whereas BSO had no effect. In platelets stored in a platelet additive solution (T-sol), complete depletion of GSH was found in the presence of cysteamine, GSH and BSO. Endogenous serotonin was unchanged during storage both in plasma and in additive solution (2.8 nmol per 109 platelets). Despite almost total depletion of endogenous GSH, the thrombin-induced release of serotonin after 5 days' storage was significantly affected only in the presence of BSO in platelets stored in additive solution (mean values 72.3% vs. 63.3% of endogeneous serotonin, P < 0.05). Similarly, addition of cysteamine or GSH had no significant effect on swirling but BSO reduced the swirling score after 5 days' storage in platelet additive solution compared with plasma. After 10 days' storage, there was a significant reduction in swirling in the concentrates where BSO was added (P < 0.05).     

复方电解质注射液作添加液汇集血小板的研究

目的探讨复方电解质注射液作添加液（PAS）汇集多人份混合血小板的可行性。方法从400ml全血中分离白膜层（BC）,容量40～45ml,于22℃±2℃静置过夜,将ABO同型的6袋白膜汇集,加200ml复方电解质注射液稀释白膜,稀释后的白膜在温度22℃±2℃的离心机中,以900r／min离心10min。上层富含血小板悬液经白细胞过滤器去除白细胞,并转移到血小板保存袋内,即制备成1个成人治疗量的PAS汇集BC—PCs。结果共制备10个成人治疗量的PAS汇集BC—PCs,其容量、血小板含量、WBC混入量、RBC混入量分别为：（293±22）ml、（3．01±0．29）×10^11、（1．1±0．2）×10^6、（5．9±1．3）×10^3。保存8d后的pH、低渗休克反应率（HSR）、形变能力（ESC）、CD62P表达率、AnnexinV结合率分别为7．10±0．05、（65．6±7．1）％、（7．1±1．6）％、（27．4±3．3）％、（12．0±1．4）％。结论复方电解质注射液作为添加液汇集血小板的方法可行。     

Evaluation of a whole-blood WBC-reduction filter that saves platelets: in vitro studies

BACKGROUND: In this study, a new WBC-reduction in-line filter that removes WBCs but not platelets was evaluated. Three WBC-reduced blood components were prepared: RBCs, plasma, and platelet concentrates (PCs). STUDY DESIGN AND METHODS: Whole-blood components (n = 30) were filtered within 2 to 4 hours after collection and then were centrifuged and separated into RBCs, plasma, and WBC-reduced buffy coat. Saline-adenine-glucose-mannitol solution was added to the RBCS: The WBC-reduced buffy coats were stored overnight; on the following day, PCs were prepared from pooled WBC-reduced buffy coats and stored in a medium composed of approximately 35 percent CPD plasma and 65 percent platelet additive solution (T-Sol, Baxter). The WBC-reduction capacity of the filter, the recovery of cells after filtration, and the in vitro storage of RBCs (n = 10) and platelets (n = 6) were evaluated. RESULTS: Mean and maximum WBC counts after filtration were 0.08 x 10(6) and 0.3 x 10(6), respectively, per filtered whole-blood unit. Recovery of RBCs (mean values) after filtration was 90 percent in whole-blood components and 73 percent in RBCS: Recovery of platelets (mean values) was 81 percent after filtration and 66 percent in PCS: The in vitro storage study of RBCs showed results comparable with previously published data, except for a lower degree of hemolysis. In the in vitro platelet storage study, results were compared with those of standard preparations. In all essentials, similar results were found. CONCLUSION: The results of the present study suggest that effective WBC reduction meets current standards and satisfactory recovery after filtration. The storage characteristics for RBCs and PCs are similar to those of standard preparations. Use of a whole-blood in-line filter to save platelets is a new option for whole-blood processing, which may simplify WBC reduction and blood component preparation, as well as reduce costs in the future.     

Extended storage of platelets in a new plastic container. I. Biochemical and morphologic changes

A new polyvinyl chloride container plasticized with tri(2-ethylhexyl) trimellitate (PL 1240 plastic) was evaluated for use in extended platelet storage. Six leukocyte-rich platelet concentrates (mean, 0.6 X 10(9) white cells per bag; range, 0.3 to 1.0 X 10(9) per container) were prepared by removing as much of the platelet-rich plasma from blood as possible. The cells were stored at 22 degrees C on an end-over-end agitator. An average of 1.04 +/- 0.19 X 10(11) platelets was recovered, and the mean pH dropped from 7.23 on day 0 to 6.68 by day 5. At the completion of the storage period. PO2 averaged 80 torr, PCO2 was 35 torr, bicarbonate concentration was 0.5 mM, and lactate concentration 29.5 mM. Thirty-one additional units of platelet concentrates, not deliberately prepared to be leukocyte-rich, on day 5 had a pH of 6.75 +/- 0.39 (mean platelet yield, 0.97 +/- 0.21 X 10(11); PO2 and PCO2 averaged 50 and 48 torr, respectively). Following storage, the cells had an average phase microscopic morphology score of 244 (n = 17). Platelets appeared to be preserved well throughout storage when assessed by transmission and scanning electron microscopy. We conclude that platelets can be stored for 5 days in PL 1240 plastic containers with good preservation of pH and cell ultrastructure.     

Phosphatidylserine exposure in platelet concentrates during the storage period: differences between the platelets collected with different cell separators.

BACKGROUND AND OBJECTIVES: Platelet alterations occur during the production and storage of platelet concentrates, the so called "storage lesion". We studied the platelet alterations during the storage period in apheresis concentrates, employing flow cytometry for phosphatidylserine (PS) detection on platelets during the five days of storage. MATERIAL AND METHODS: Twenty-seven single donor platelet concentrates harvested with the Cobe Trima, Baxter Amicus, or Haemonetics MCS+ were analyzed for PS exposure by flow cytometry on the day of production (day 1) and on days 3 and 5 of storage. Furthermore PS expression was analyzed in platelet donors' blood samples withdrawn before plateletpheresis. RESULTS: PS expression on platelets gave the following median values: in blood donors before apheresis it was 1.12% (0.13-1.78) in platelets concentrates on the first day (2 h after apheresis) 2.06% (0.66-15.2), the third day 6.57% (1.98-51.13) and the fifth day 23.04% (3.86-80.23). All differences between median values of PS expression in blood samples before apheresis, and platelets concentrates on days 1, 3 and 5 of storage, are statistically significant. The expression of PS in platelet concentrates was analyzed in relation to the blood cell separator used for the collection procedure and showed the following results: on day 1 the median values of PS in platelet concentrates collected with the three different blood cell separators, Trima, Cobe and MCS, did not show statistically significant differences. On day 3, the platelets concentrates collected with the Trima and with the MCS showed differences that were statistically significant. Those were respectively 10.59% (4.56-51.13) and 3.53% (1.98-12.61), p = 0.005. The PS expression in platelet concentrates collected with the Trima and MCS showed differences that are also statistically significant on day 5 at respectively 32.4% (9.61-80.23) and 8.57% (3.86-48.42), p = 0.005. CONCLUSIONS: PS exposure in platelet concentrates on days 3 and 5 rise to levels that could compromise the quality of the platelet units. Improvements in standardized platelet quality controls, and in platelet collection systems are required to reduce the storage lesions in platelets concentrates.     

白膜放置时间对制备手工浓缩血小板质量的影响

目的评价全血当天分离的白膜(BC)在不同时间分离制备的浓缩血小板(PC)的质量,为手工制备PC提供参考。方法将80袋400 mL全血于采集6 h内分离出BC,将5袋同血型BC由无菌接驳机对接合并成1袋(1个治疗量)后,再均分在3个血小板保存袋内,1袋即刻(0 h组)轻离心分离制备PC,另2袋在22℃血小板保存箱分别振摇4 h(4 h组)和16 h(16 h组)后再分离PC。对所有标本留样进行血小板质量检测,包括Plt、血小板回收率、CD62P、聚集率、RBC混入量、WBC混入量、FHb含量。结果 3组PC制剂RBC混入量、Plt、血小板回收率、CD62P、聚集率差异无统计学意义;WBC混入量:0 h(6.76±1.29)和4 h组变化不明显,16 h(3.78±0.45)组降低明显(P<0.05);FHb含量:随BC处理时间延长有增高趋势,16 h(65.62±11.11)与0 h(33.45±6.95)比差异具统计学意义(P<0.05)。结论随BC放置时间延长对制备PC制剂的质量有一定影响。     

The effects of irradiation on platelet function

Current medical practice involves the irradiation of blood components, including platelet concentrates, before their administration to patients with severe immunosuppression. The authors studied the effect of irradiation on in vitro platelet function and the leaching of plasticizers from the bag, both immediately and after 5 days of storage. The platelet count, white cell count, pH, glucose, lactate, platelet aggregation and release reaction, and serotonin uptake were not altered by the irradiation of random-donor or apheresis units with 2000 rads carried out at 0 and 24 hours and 5 days after collection. The leaching of di(2-ethylhexyl)phthalate from the plastic bags followed by the conversion to mono(2-ethylhexyl)phthalate was not increased by irradiation. Therefore, it is possible to irradiate platelet concentrates on the day of collection and subsequently store them for at least 5 days while maintaining in vitro function. This procedure could have considerable benefit for blood banks involved in the provision of many platelet products.     

Storage of platelets in additive solution for up to 12 days with maintenance of good in-vitro quality

BACKGROUND: Storage of PLT concentrates (PCs) may be extended beyond 5 days, provided in-vitro and in-vivo variables allow longer storage and bacterial screening is performed. The aim of this study was to examine in-vitro storage characteristics of PCs in various storage solutions: plasma only, or mixtures of plasma with PAS-II, PAS-III, PAS-IIIM, and Composol. STUDY DESIGN AND METHODS: PCs from five pooled buffy-coats and WBCs reduced by filtration were stored in 1.3-L butyryl-tri-hexyl-citrate-plasticised PVC containers. First, a paired comparison was made between PAS-II and Composol, with 35-percent final plasma concentration (n = 10). Then, plasma, PAS-III with 30-percent plasma, PAS-IIIM with 20- and 30-percent plasma, and Composol with 20 and 30-percent final plasma concentration were compared (n = 5 pairs). Finally, 50 PCs in Composol with 35-percent final plasma concentration were studied. RESULTS: PCs in PAS-II or Composol had a mean +/- SD pH of 6.95 +/- 0.09 and 6.96 +/- 0.08 at Day 12, respectively. For PCs in PAS-IIIM and Composol with 30-percent final plasma concentration, pH on Day 7 was 7.00 +/- 0.02 and 6.83 +/- 0.05. With 20-percent final plasma concentration, pH was 6.98 +/- 0.02 and 6.81 +/- 0.03 for PAS-IIIM and Composol, respectively. PCs in PAS-III with 30-percent plasma had a pH on Day 7 of 6.87 +/- 0.03, whereas PCs in 100-percent plasma had a pH of 7.05 +/- 0.03. PCs in Composol with 35-percent plasma maintained pH greater than 6.8 in 48 of 50 of the units (96%), averaging 7.00 +/- 0.10 on Day 8. CONCLUSION: In-vitro quality of PCs in AS with at least 35-percent plasma can be maintained for 7 to 12 days after collection.     

In vitro evaluation of COM.TEC apheresis platelet concentrates using a preparation set and pathogen inactivation over a storage period of five days

The aim of the present study was to evaluate in vitro data on platelets collected by apheresis, processed on a preparation set followed by photochemical treatment (PCT). Fifteen single-donor platelet concentrates (PCs) were collected by apheresis (COM.TEC blood cell separator, Fresenius, Bad Homburg, Germany). The platelets were transferred to the preparation set and plasma was removed after centrifugation to resuspend the platelets in approximately 37% plasma and 63% platelet additive solution InterSol. PCT was done by exposing the platelets to amotosalen HCl followed by illumination with ultraviolet light. Blood cell counts and in vitro PLT function were measured up to 5 days. An average of 3.44 +/- 0.28 x 10(11) platelets were collected in a product volume of 351 +/- 21 mL. Plasma removal resulted in a mean platelet loss of 7.8%. After PCT, a progressive decrease in platelet function was observed. LDH level rose through storage (171 +/- 81 U/L) to levels approximating LDH levels observed post-collection (180 +/- 103 U/L). There was a gradual decrease of the platelets to respond to hypotonic shock response from 90 +/- 9 % post-plasma reduction to 48 +/- 16% at day 5. All PLT units met the European requirements for leukoreduction and the pH limit of 6.8 up to day 5 post-collection. The new preparation set was capable of producing platelet units meeting the requirements for PCT. Despite differences observed in in vitro platelet function parameters, PLTs at storage day 5 fit the German and European guidelines.     

Paired comparison of apheresis platelet function after storage in two containers

Platelet quality after storage strongly depends on the pre-storage quality as well as on the storage conditions determined by the storage container. In this paired study, we evaluated two different containers (MedSep CLX and Delmed DPL-110). The Fresenius AS104 cell separator was used to prepare 17 platelet concentrates that were split and distributed into the containers to be compared. Cell counts, blood gas analysis, morphological scores, glucose and lactate levels, platelet activation, and platelet aggregation were measured before splitting at the day of preparation and after storage at day 3 and day 5. At day 3, there was no significant difference between the two bags apart from increased lactate and decreased pCO(2) concentrations in the CLX bags. At day 5 there were significantly higher lactate concentrations, pO(2) levels, and aggregation after stimulation in the CLX group, while the glucose and pCO(2) concentrations were significantly lower in these platelet concentrates as compared to the DPL-110 group. However, these parameters did not influence the functional parameters tested. While the platelet quality decreased during storage in all bags, the functional changes were nearly identical in both bags tested. We conclude that both bags are equivalent for 5-day storage of platelet concentrates.     

Platelet apoptosis and activation in platelet concentrates stored for up to 12 days in plasma or additive solution

Background: Several studies suggest that apoptosis of platelets occurs during storage of platelet concentrates (PC). We sought to determine whether storage of PC in additive solution alters levels of apoptosis during storage beyond the current shelf life (5–7 days). Study design and methods: Pooled buffy coat PC (n = 7) were prepared in either 100% plasma or 70% Composol and stored at 22 °C for 12 days. A third arm of the study stored PC in 100% plasma at 37 °C, which is thought to induce apoptosis. PC were tested for mitochrondrial membrane potential, annexin V binding, microparticles, caspase‐3/7 activity and decoy cell death receptor 2, as well as standard platelet quality tests. Results: Composol units remained ≥pH 6·88, with 36% lower lactate and higher pH vs plasma by day 12 (P < 0·001). Platelet function was better maintained, and activation and apoptotic markers tended to be lower in Composol units towards the end of storage. However, levels of all apoptosis markers assessed were not significantly different in units stored in Composol. Storage at 37 °C saw stronger correlation of apoptotic markers with standard quality tests compared to 22 °C, but loss of correlation of caspase‐3/7 activity with other apoptosis markers. Conclusion: We conclude that storage of platelets in 70% Composol vs 100% plasma does not increase the rate of platelet apoptosis. Our data agree with other studies suggesting that platelet apoptosis is sequential to high levels of activation, but share a significant degree of overlap.     

Platelet ADP response deteriorates in synthetic storage media

BACKGROUND: During storage under blood bank conditions, platelets (PLTs) are known to secrete ADP. PLT stimulation by ADP results in refractoriness to restimulation, making this response one of the most unstable PLT reactions. The goal of this study was to evaluate the ADP-induced responses of PLTs stored in full plasma or in plasma and additive solution (AS). STUDY DESIGN AND METHODS: Surface expression of P-selectin, ADP-induced aggregation, and reconstituted whole-blood thrombus formation were determined on collagen surfaces in a perfusion model with PLTs that were stored for 4 days either in plasma or in the presence of plasma with PAS-II or Composol. RESULTS: After 4 days of storage in PAS-II but not in Composol, the percentage of PLTs that had secreted granule contents (P-selectin) was increased, when compared to PLTs stored in full plasma. Maximal aggregation in response to ADP was reduced for PLTs stored in PAS-II or Composol. Resuspension of these PLTs in plasma at 37 degrees C for 1 hour caused partial recovery of the aggregation response. Addition of apyrase to PLTs in AS preserved the responsiveness toward ADP. Titration experiments indicated that this response gradually decreased with decreasing plasma concentration. The functional significance of these findings was demonstrated by perfusion experiments. Thrombus formation on collagen was significantly higher for PLTs stored in full plasma than for PLTs stored in PAS-II or Composol. CONCLUSIONS: Storage of PLTs in the presence of AS under blood bank conditions induces deterioration of the PLT responsiveness to ADP compared to PLT concentrates in 100 percent plasma. Higher plasma-to-AS ratios result in better preserved responses.     

PAS or plasma for storage of platelets? A concise review

Platelet additive solutions (PASs) are becoming increasingly popular for storage of platelets, and PAS is steadily replacing plasma as the storage medium of platelets. PASs are electrolyte solutions intended for storage of platelets, and they are used to modulate the quality of the platelets by adding specific ingredients. All currently available PASs contain acetate. Acetate reduces the amount of glucose that is oxidised into lactic acid and thereby prevents the lowering of pH, which decreases platelet quality. Furthermore, the oxidation of acetate leads to the production of bicarbonate, which serves as buffer. The presence of potassium and magnesium in PAS prevents the lowering of pH and reduces the degree of spontaneous activation of the platelets during storage. In the hospital, platelets stored in PAS result in about half of the number of allergic transfusion reactions as compared with platelets in plasma. Recovery and survival after transfusion, as well as corrected count increments, are at least as good for platelets in PAS as for plasma, and recent data suggest they may even be better. Therefore, with the current generation of PASs, PAS should be preferred over the use of plasma for the storage of platelet concentrates.