Extent Of Shape Change Research Articles

Quality validation of platelets obtained from the Haemonetics and Trima Accel automated blood-collection systems.

Platelet transfusion is required to treat haemo-oncology or trauma patients. Platelet apheresis (PA) performed with apheresis equipment has increased rapidly in recent years. Leucocyte-reduced platelet apheresis (LRPA) can reduce the risk of platelet refractoriness and febrile nonhemolytic transfusion reactions (FNHTRs) for transfusion. Accordingly, this study aimed to investigate and compare the platelet metabolic and functional responses between PA performed with Haemonetics and LRPA performed with Trima Accel cell separator. The qualities of platelets collected through PA and LRPA were evaluated in terms of visual appearance, morphology, platelet-aggregation changes, metabolic activities, and bacterium-screening test during 5-day storage. Statistical analyses included two-sample t-test and generalised estimating equation(GEE) method. During 5-day storage in LRPA, residual leucocytes were all <1.0×106, and the parameters of platelet function were as follows: platelet aggregated to agonists such as adenosine 5'-diphosphate (ADP) and collagen, and the extent of shape change and pO2 showed no statistically significant difference between PA and LRPA. The hypotonic shock reaction (HSR) on days 0, 1, and 3 were significantly higher in LRPA than in PA (71.78±6.92 vs. 64.10±7.42; P=0.002; 71.53±8.98 vs. 62.96±9.84; P=0.007; 68.05±7.28 vs. 57.76±6.80; P<0.0001, respectively). Values of mean platelet volume (MPV) were statistically larger in PA than in LRPA on days 0, 1, and 3. On day 5, the swirling score was higher in LRPA than in PA. The mean lactate levels had no statistically significant difference between PA and LRPA. Moreover, no growth was observed through bacterium-screening test conducted on 40 samples. Comparison of LRPA and PA products collected from the Trima Accel and Haemonetics automated blood-collection systems, respectively, revealed that both products possessed good platelet qualities even though additional processes are needed to reduce leucocytes. Furthermore, investigating the outcomes of other apheresis instruments with focus on the safety of donors, products, and recipients is necessary.

Influence of apheresis collection device and container on the storage properties of platelets in 90% PAS-5/10% plasma.

The storage properties of apheresis platelets suspended in the experimental additive solution PAS-5 and 10% plasma may be affected by the collection instrument or storage container. The same consenting 12 donors provided A or T platelets with concurrent plasma on four occasions in 100% plasma. Following collection and resting, the platelets were centrifuged, and plasma was expressed and resuspended in PAS-5 to yield units with 10% plasma. Platelets were either maintained in the original storage container or transferred to another of the manufacturer's storage containers. On days 1, 5 and 7, units were assayed for an array of in vitro tests. Average unit volume, yield and percent plasma was 291±11 mL, 3.7±0.4×1011, and 10.3±0.7%, respectively, and were comparable between collections with either of the apheresis instruments and stored with either of the manufacturer's containers. Day 1 platelet activation (CD62P+) was 40±22% and was similar in either of the collection instruments or containers. Except for pH (days 1, 5), CO2 (days 1, 5, 7), and extent of shape change (day 5), every other in vitro parameter was similar between apheresis platforms or the manufacturer's container. pH values of all units on all days of storage were ≥6.8, except one unit that was collected on T and stored in an A container, which had pH values of 6.8 and 5.7 on days 5 and 7, respectively. Storage of platelets suspended in PAS-5 with 10% plasma is feasible in the original manufacturer's container for seven days. Based on CO2 levels, T containers have greater gas exchange than A containers.

RhoA/ROCK signaling contributes to sex differences in the activation of human platelets

Studies of sex-dependent differences in platelet aggregation and glycoprotein (GP)IIb/IIIa activation have demonstrated that platelets from females are more sensitive to agonists than those from males. To date, there is little understanding of these differences at a molecular level. Here, sex differences in reactivity of platelets from 86 women and 86 men were investigated. Platelet degranulation (CD62P expression) and activation of GPIIb/IIIa (PAC-1 binding), with and without ADP, were assessed. Extent of shape change (ESC) in response to ADP was measured. Basal CD62P and PAC-1 expression did not differ between the sexes. In response to ADP activation, mean PAC-1 binding in platelets from female donors was 17.9±3.5% vs. 14.0±4.1% in platelets from male donors, and ESC was significantly greater in platelets from females (p<0.05). Evaluation of basal expression of signaling molecules along the ADP receptor pathway leading to GPIIb/IIIa activation and subsequent RhoA/ROCK signaling via GPIIb/IIIa 'outside-in' signaling showed that platelets from females produce 3-fold greater levels of phosphorylated protein kinase C (PKC) substrates. There was a 2.5-fold greater level of activated RhoA, and platelet sub-fractionation analysis demonstrated 2.7-fold more RhoA in the membrane fraction of female vs. male platelets. Similarly, there was a 2.8-fold increase in levels of phosphorylated myosin light chain (MLC) in platelets from females vs. males. The increased signaling activity in platelets from females mirrors their greater sensitivity to agonists. These findings further our understanding of the molecular differences between platelets from males and females.

Correlation of the hypotonic shock response and extent of shape change with the new ThromboLUX ™.

ThromboLUX (TLX)-Score was compared with hypotonic shock response (HSR) and extent of shape change (ESC) in 99 samples from 42 platelet concentrates. Tests were performed in parallel and duplicate. Mean values for TLX Score, HSR and ESC were 30.3 ± 3.8%, 69.0 ± 12.2% and 23.2 ± 4.9%, respectively. We found no significant correlation between TLX Score and HSR or ESC (r = -0.158, P = 0.118 and r = -115, P = 0.255, respectively), whereas HSR and ESC correlated significantly (r = 0.351, P < 0.001). As TLX Score did not show significant correlation with HSR and ESC, the value of TLX for platelet quality testing remains unclear. Studies comparing these parameters with transfusion outcome are needed.

A rest period does not affect in vitro storage properties in apheresis platelets collected from the buffy coat layer

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. 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. 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%). The in vitro storage properties of Trima apheresis PLTs isolated from the buffy coat layer do not benefit from a rest period.

High‐yield Platelet units revealed immediate pH decline and delayed mitochondrial dysfunction during storage in 100% plasma as compared with storage in SSP+

Initial elevated and prolonged high carbon dioxide levels related to mitochondrial dysfunction are recently being suggested as a contributing factor to rapid pH decline in platelet (PLT) units. The use of different storage environments may influence this phenomenon. This study has two objectives (i) to investigate the relationship of mitochondrial function and apoptotic events with different storage environments capability of pH control and (ii) to examine the cause and relationship between pH decline in PLT units, carbon dioxide levels and mitochondrial function. Platelet units were prepared for storage in (A) 70% SSP+, 300-400 × 10(9) /unit, (B) 70% SSP+, 550-600 × 10(9) /unit, (C) 100% plasma, 550-600 × 10(9) /unit, and (D) additional 100% plasma, >600 × 10(9) /unit. In vitro variables including mitochondrial function (JC-1), reactive oxygen species (ROS) and caspase 3 activity were analysed on days 2, 5 and 7. Glucose/lactate was higher, pH, ATP, Hypotonic shock response (HSR) and extent of shape change (ESC) decreased (P < 0·001 on day 7), CD62P (P < 0·001 on day 7) increased, the JC-1-positive PLTs were lower (P < 0·001 on day 7), and ROS was higher (P < 0·001 days 2-7) in the plasma (C) units as compared with the SSP+ (A) and (B) units. All plasma (D) units showed rapid pH and pCO(2) decline from day 2 but by means of >80% maintenance of mitochondrial function until day 7. The use of SSP+ instead of plasma may reduce the risk of triggering pro-apoptotic events in high-yield PLT units. A rapid decline in pH in PLT units cannot be explained with initial elevated and prolonged high carbon dioxide levels and mitochondrial dysfunction.

Effects of immediate or delayed addition of platelet additive solution on the in vitro quality of apheresis platelets

There is little knowledge how different hold times of hyperconcentrated platelet (PLT) suspensions (HPSs) before the addition of platelet additive solution (PAS) might affect PLT quality. We compared the in vitro quality of single-donor PLT concentrates (SDPs) with immediate or delayed PAS addition and studied the quality of collected concurrent plasma (CP). We collected 6×10(11) PLTs in 175 of mL plasma and CP from 31 donors. The HPSs were split into two parts, with 162 mL of modified PAS III (PAS-IIIM) added immediately (0hr-SDP) or 2 hours later (2hr-SDP). Final SDPs had a targeted concentration of 1.2×10(12) PLTs/L and a PAS proportion of 65%. On Days 1, 5, and 7 we determined glucose and lactate concentration, pH, P-selectin expression, hypotonic shock response (HSR), and extent of shape change (ESC). Clotting Factor V (FV) and VIII (FVIII) activities and D-dimer concentration were determined in CP and donor. Glucose utilization, lactate production, and pH were similar for both kinds of products. Low P-selectin expression indicated no relevant PLT activation during storage. HSR and ESC were similarly well preserved. Recoveries of FV and FVIII were 100.0±14.0 and 98.6±14.9%, respectively. Concentrations of D-dimers in the donor and CP were 173.7±90.1 and 177.6±91.2 ng/dL, respectively. Adding PAS immediately or 2 hours after collection does not result in different in vitro quality of PLTs stored up to 7 days. The good recovery of clotting factors with no signs of activation indicates a good quality of CP.

Development of a quality monitoring program for platelet components: a report of the first four years' experience at Canadian Blood Services

A quality monitoring program (QMP) for platelet concentrates (PCs) was implemented at Canadian Blood Services (CBS) to improve standards and to better understand platelet (PLT) products by supplementing routine quality control (QC). Annual surveys of PCs from CBS production sites were conducted, with four completed to date (QMP Cycles 1-4) spanning two different PC production methods: PLT-rich plasma (PRP) and buffy coat (BC). Randomly selected PCs were sent to a central laboratory and tested 1 day after expiry. An expanded panel of tests including CD62P expression by flow cytometry, mean PLT volume, PLT count and morphology, extent of shape change, and PLT metabolic parameters, were applied. QMP data on the implementation of the BC production method across CBS indicated that BC PCs have less variable in vitro quality measures than PRP PCs. For the QC parameters pH and PLT count per unit, the range of mean values from each site for QMP 3 and 4 fell well within the range defined by regulatory standards, a first step in defining quality benchmarks for PCs. Of the extended panel of quality parameters, CD62P expression was the most sensitive indicator of change and identified an issue with the implementation of the BC PC production method at one site, which was subsequently remedied. A QMP was found to be useful to monitor production processes across sites and highlights best practice approaches while deepening understanding of the quality of PLT products at CBS.

Comparative in vitro evaluation of apheresis platelets stored with 100% plasma or 65% platelet additive solution III/35% plasma and including periods without agitation under simulated shipping conditions

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). 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. 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. 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.

In vitro variables of apheresis platelets are stably maintained for 7 days with 5% residual plasma in a glucose and bicarbonate salt solution, PAS‐5

Platelet additive solutions (PASs) facilitate improved recovery of plasma and may reduce the severity and/or frequency of plasma-associated transfusion reactions. Current apheresis platelet (PLT) PAS products contain approximately 30 to 40% residual plasma. In an effort to further decrease the residual plasma, two in vitro studies were conducted with PLTs suspended in 5% plasma and a reformulated PAS-3, named PAS-5, that contains additional salts, glucose, and bicarbonate. In Study 1, PLTs suspended in 5% plasma/95% PAS-5 were prepared directly on a separator (Amicus, Fenwal, Inc.) without additional centrifugation or washing. In Study 2, a double unit of hyperconcentrated Amicus PLTs in plasma was collected, divided, and centrifuged to prepare a control unit in 100% plasma and a paired test unit in 5% plasma/95% PAS-5. The in vitro properties of PLTs were assessed in both studies during 7-day storage at 20 to 24°C with continuous agitation. In Study 1, PLT concentration, pH, mean PLT volume (MPV), HCO(3)(-), pCO(2), pO(2), lactate dehydrogenase, and hypotonic shock response (HSR) did not significantly change during storage. By Day 7, glucose levels and morphology scores modestly decreased (17.6 and 14.4%, respectively) and lactate levels modestly increased (to 7.2 mmol/L). In Study 2, MPV, pH, glucose, pO(2), HSR, and morphology were comparable in control and test PLTs during 7-day storage. Glucose consumption and lactate production were significantly less in test versus control PLTs (p≤0.0015). Extent of shape change and %CD62P-positive test PLTs were less than those of controls (p<0.001). Apheresis PLTs suspended in 5% plasma/95% PAS-5 maintained in vitro properties during 7-day storage.

Storage of aliquots of apheresis platelets for neonatal use in syringes with and without agitation

To facilitate volume control in neonates, platelets (PLTs) are aliquoted and stored for short periods in non-gas-permeable syringes before infusion. Although agitation of PLTs during storage in gas-permeable bags is performed to maintain their quality, the effect of syringe agitation during storage is unknown. Double apheresis PLTs (n = 6) were collected and split, providing two identical products. On Days 2 and 4 of storage, aliquots from one bag of each pair were transferred to two syringes and stored for 6 hours on flatbed agitator or were left at 20 to 24 °C without agitation. A series of in vitro tests was performed on Days 0, 2 (Hours 0 and 6), and 4 (Hours 0 and 6). Control samples were obtained from the second matched bag that was stored on the agitator. Data were analyzed by one-way analysis of variance with differences considered significant if the p value was less than 0.05. Comparable results for several PLT variables were obtained with or without agitation of the syringes. On Day 4 Hour 6, pH values were 7.18 ± 0.12 (agitated syringes) and 7.19 ± 0.1 (nonagitated syringes), and extent of shape change and hypotonic shock response measurements were not significantly different between agitated syringes and nonagitated syringes (23.7 ± 6.4 and 74.3 ± 9.8% vs. 23.3 ± 5.4 and 76.0 ± 7.6%), respectively. Based on in vitro testing, apheresis PLT aliquots can be stored in syringes for at least 6 hours without agitation before transfusions.

Characterization of blood components separated from donated whole blood after an overnight holding at room temperature with the buffy coat method

With buffy coat (BC) processing of whole blood (WB) donations, increase in WB storage time to facilitate overnight holding before the separation of blood components would be a logistically attractive development. This study undertakes a comparative in vitro characterization of blood components prepared from WB samples that were either processed within 8 hours or stored overnight at room temperature before processing by the BC method. The WB units (400 mL) collected were either processed within 8 hours (fresh blood) or stored overnight (overnight blood) at room temperature. WB units were separated into individual-component red blood cells (RBCs), BC, and plasma. The in vitro quality of these blood components (RBCs, pooled platelet concentrates [PCs], and plasma) was analyzed during storage. Levels of 2,3-diphosphoglycerate (2,3-DPG) were found to be significantly lower immediately after processing, compared with the fresh WB samples, in RBCs that had been separated from an overnight-hold sample. However, this difference was not apparent after 14 days of storage. In pooled PCs, measurements for glucose, lactate, PO(2), PCO(2), extent of shape change, and hypotonic shock response were similar. The platelet yield in PCs prepared from an overnight-hold WB sample was significantly higher, while CD62P expression and annexin V binding were lower (p < 0.05). For frozen plasma (FP), no significant differences were observed for the coagulation factors (F)II, FVII, FV, F IX, FX, and FXI; fibrinogen; and von Willebrand factor content between the 8- and 24-hour FP. The FVIII was the component that was most sensitive to the prolongation of production time and it only had 80% of the activity of the 8-hour FP. These data suggest that blood components (RBCs, pooled PCs, and FP) separated from WB that has been stored overnight at room temperature by the BC method are of acceptable quality.

In vitro effects on platelets irradiated with short‐wave ultraviolet light without any additional photoactive reagent using the THERAFLEX UV‐Platelets method

A novel short-wave ultraviolet light (UVC) pathogen reduction technology (THERAFLEX UV-Platelets; MacoPharma, Mouvaux, France) without the need of any additional photoactive reagent has recently been evaluated for various bacteria and virus infectivity assays. The use of UVC alone has on the one hand been shown to reduce pathogens but may, on the other hand, have some impact on the platelet (PLT) quality. The purpose of this study was to determine the potential effects on PLT quality of pathogen inactivation treatment using the novel UVC method for PLT concentrates. Buffy-coat-derived PLTs suspended in SSP+ were irradiated with UVC light in plastic bags (MacoPharma) made of ethyl vinyl acetate, considered to be highly permeable to UVC light. The UVC-treated (test, n=8) as well as the untreated (reference, n=8) PLT units were stored in PLT storage bags composed of n-butyryl, tri n-hexyl citrate-plasticized polyvinyl chloride (MacoPharma) on a flat bed agitator for in vitro testing during 7 days of storage. No significant difference in PLT counts and lactate dehydrogenase between the groups was detected. During storage, glucose decreased more and lactate increased more in the test units. Statistically significant differences were found for glucose (P<0·01) and lactate (P<0·05) on day 7. ATP levels were higher (P<0·01 from day 5) in the reference units. With exception of day 7 (P<0·01 reference vs. test), hypotonic shock response reactivity was not different between groups. Extent of shape change was lower (P<0·01), and CD62P (P<0·05 day 5) was higher in the test units. CD42b and CD41/61 showed similar trends throughout storage, without any significant difference between the units. pH was maintained at >6·8 (day 7) and swirling remained at the highest level (score = 2) for all units throughout storage. Our results suggest that irradiation with UVC light has a slight impact on PLT in vitro quality and appears to be insignificant with regard to current in vitro standards.

Storage of interim platelet units for 18 to 24 hours before pooling: in vitro study

The Atreus 3C system (CaridianBCT) automatically produces three components from whole blood (WB), a red blood cell (RBC) unit, a plasma unit, and an interim platelet (PLT) unit (IPU) that can be pooled with other IPUs to form a PLT dose for transfusion. The Atreus 3C system also includes a PLT yield indicator (PYI), which is an advanced algorithm that provides an index that is shown to correlate well with the amount of PLTs that finally end up in the IPU bag. The aim of our in vitro study was to compare the effects of holding WB overnight versus processing WB fresh (2-8 hr), both with 18- to 24-hour storage of the IPUs before pooling into a transfusable PLT dose. WB was processed either fresh (within 8 hr after collection, Atreus F) or after overnight storage (14-24 hr, Atreus S) without agitation at 22 ± 2 °C. After a subsequent resting time of 18 to 24 hours on a flat-bed shaker, five IPUs were selected for pooling with 200 mL of PAS II for in vitro quality assessments during a 7-day storage period (n = 10 in each arm). IPUs were selected for pooling using the PYI of the Atreus 3C system. During storage, the glucose concentration was lower (p < 0.05) and the lactate concentration was higher (p < 0.05) in Atreus S pools, but no differences in the glucose consumption rate were noted. Adenosine triphosphate levels and hypotonic shock response reactivity were higher in Atreus S (p < 0.05). No significant differences in PLT counts, contents, mean PLT volume, lactate dehydrogenase, pO(2) , pCO(2) , extent of shape change, and CD62P between groups were detected. pH was maintained higher than 6.8 (Day 7). With exception of 2 units in the Atreus S arm, swirling remained at greater than 2 in all units at all times. Our results suggest that PLTs prepared from fresh or overnight-stored WB and pooled after 18 to 24 hours meet necessary in vitro criteria without any relevant differences between both groups. Using the PYI, comparable yields can be obtained between WB processed within 2 to 8 hours and WB stored overnight.

Storing apheresis platelets without agitation with simulated shipping conditions during two separate periods: immediately after collection and subsequently between Day 2 and Day 3

Apheresis platelet (PLT) units are not routinely agitated during transit. Our study compared the in vitro properties of apheresis PLT units that were stored with continuous agitation (CA) and without continuous agitation (WCA) during two separate periods, immediately after collection and between Day 2 and Day 3 of storage. Two identical apheresis PLTs units were prepared from collections with Amicus (n = 11, Fenwal, Inc.) and Trima (n = 10, CaridianBCT) cell separators. One apheresis PLT unit was continuously agitated, starting routinely within 30 minutes of collection, and an identical apheresis PLT unit was held without agitation initially for 7 to 8 hours and subsequently for 24 hours between Day 2 and Day 3 of storage. The apheresis PLT units were maintained WCA at 20 to 24 °C in a shipping box. In vitro PLT properties were evaluated on Day 1 (day after collection), after 5 and 7 days of storage. With both Amicus and Trima apheresis PLT units, the mean PLT content and concentration of CA and WCA were comparable and essentially constant throughout storage. Mean pH levels (± 1 SD) after 5 days for Amicus apheresis PLT units were 6.97 ± 0.20 (WCA) and 7.13 ± 0.16 (p < 0.001, CA) and for Trima apheresis PLT units 6.97 ± 0.21 (WCA) and 7.22 ± 0.17 (p < 0.001, CA). In vitro variables, including percentage of disc PLTs, extent of shape change, and hypotonic stress levels, after 5 days of storage, showed mean differences between WCA and CA that were less than 15%. The in vitro results show that apheresis PLT units can be stored without agitation for 7 to 8 hours immediately after collection and also subsequently during storage for 24 hours with minimal influence on in vitro PLT properties compared to continuously agitated PLTs.

Storage of Buffy-coat-derived platelets in additive solutions: in vitro effects on platelets prepared by the novel TACSI system and stored in plastic containers with different gas permeability

The novel TACSI system is designed for automated preparation of platelets (PLTs) from pooled buffy coats (BCs). One TACSI device will handle 6 units at the same time. The aim of our in vitro study is to investigate the effects of using this automated equipment with subsequent storage in two different plastic containers and to compare these results with PLTs prepared by the OrbiSac system. Buffy-coat-derived PLTs (n=8) were prepared by using the TACSI system, including storage in polyvinyl chloride (PVC)-based plastic containers with di, n-decyl phthalate (DnDP) (TACSI R) and BTHC (TACSI T)-based plasticizers. As a reference, the OrbiSac System was used to prepare PLTs (n=8) with subsequent storage in a PVC plastic container with a citrate-based plasticizer (BTHC). In total, 16 TACSI and eight reference units, supplied by approximately 30% plasma and 70% SSP+, were analysed for various in vitro variables during the 7-day storage period. No significant difference in PLT counts, LDH, mean platelet volume (MPV) and adenosine triphosphate between the groups was detected. Glucose was lower (P<0·05) and lactate was higher (P<0·05) in TACSI R vs. OrbiSac. With exception of day 7 (P<0·05 TACSI R vs. OrbiSac), HSR reactivity were not different between groups. Extent of shape change was lower and CD62P higher in TACSI T when compared with TACSI R and OrbiSac units (P<0·05). pH was maintained at >6·8 (day 7) and swirling remained at the highest level (score=2) for all units throughout storage. Platelets prepared by the TACSI system with subsequent storage in two different PVC-based plastic containers were equivalent to reference PLTs with regard to in vitro characteristics during 7 days of storage.

Extended storage of platelet-rich plasma-prepared platelet concentrates in plasma or Plasmalyte.

Using bacterial detection or pathogen reduction, extended platelet (PLT) storage may be licensed if PLT viability is maintained. The Food and Drug Administration (FDA)'s poststorage PLT acceptance guidelines are that autologous stored PLT recoveries and survivals should be 66 and 58% or greater, respectively, of each donor's fresh PLT data. Nonleukoreduced PLT concentrates were prepared from whole blood donations. Autologous PLT concentrates from 62 subjects were stored in 100% plasma (n=44) or 20% plasma/80% Plasmalyte (n=18), an acetate-based, non-glucose-containing crystalloid solution previously used for PLT storage. Fresh PLTs were obtained on the day the donor's stored PLTs were to be transfused. The fresh and stored PLTs were alternately radiolabeled with either (51) chromium or (111) indium, and in vitro measurements were performed on the stored PLTs. The FDA's PLT recovery criteria were met for 7 days of plasma storage, but PLT survivals maintained viability for only 6 days. Plasmalyte-stored PLTs did not meet either acceptance criteria after 6 days of storage. After 7 days of storage, PLT recoveries averaged 43±4 and 30±4% and survivals 4.1±0.4 and 2.0±0.2 days for plasma- and Plasmalyte-stored PLTs, respectively (p=0.03 for recoveries and p<0.001 for survivals). Poststorage PLT recoveries correlated with the commonly used in vitro PLT quality measurements of hypotonic shock response and annexin V binding, while survivals correlated with extent of shape change, morphology score, and pH. There is a progressive decrease in recoveries and survivals of plasma-stored PLTs over time. PLT viability is better maintained in plasma than Plasmalyte.

Calcium is a key constituent for maintaining the in vitro properties of platelets suspended in the bicarbonate‐containing additive solution M‐sol with low plasma levels

Commercially available additive solutions (ASs) require 30% to 35% plasma for optimal storage of platelets (PLTs). PLTs suspended in M-sol, a bicarbonate-based experimental platelet additive solution (PAS), maintain in vitro PLT properties during storage with low levels of plasma (< or =5%). Four different formulations of M-sol were prepared at the optimal pH (6.1): M-sol, M-sol without calcium, M-sol without citric acid, and M-sol without calcium and citric acid. Apheresis PLT units (100% plasma) were equally divided into five 50-mL aliquots in PL732 containers, centrifuged, and resuspended to prepare units suspended in the four different PASs (95%) with 5% plasma and 1 unit in 100% plasma. Units (n = 10) were stored under standard conditions and assayed for in vitro properties on Days 1, 5, and 7. The data were analyzed by analysis of variance for repeated measures (n = 10, p < 0.001). On Day 5 of storage, PLTs suspended in the M-sol formulation containing calcium but lacking citric acid had similar pH, extent of shape change (ESC) values, and percentage of CD62-positive PLTs and greater hypotonic shock response (HSR) and percentage of discoid PLTs compared to those of PLTs suspended in 100% plasma. In contrast, PLTs suspended in the M-sol formulation lacking calcium had lesser ESC values, greater percentage of CD62-positive PLTs, and similar HSR values and percentage of discoid PLTs compared to those of PLTs suspended in 100% plasma on Day 5 (p < 0.001). Calcium plays an important role in maintaining CD62-negative PLTs and relatively high ESC in 5% plasma. The removal of citric acid from M-sol may improve PLT storage properties with low plasma levels.

Effects of pretransfusion warming of platelets to 35°C on posttransfusion platelet viability

Three of four prior studies suggested that warming platelets (PLTs) to 37 degrees C before transfusion into patients with thrombocytopenia gave improved corrected PLT count increments. Eighteen normal subjects had apheresis PLTs collected that were stored at 22 degrees C for 5 days in two storage bags. One bag of PLTs was warmed to 35 degrees C before infusion, and one remained at 22 degrees C. Three different methods of warming the donor's autologous PLTs before reinfusion were evaluated: warming PLTs to 35 degrees C for 10 or 60 minutes followed by radiolabeling or radiolabeling the PLTs followed by warming to 35 degrees C for 60 minutes. In the first two methods, the warmed PLTs would have returned to 22 degrees C before infusion, and in the third, the PLTs would still be warm when injected. The paired test and control PLTs were radiolabeled with either (111)In or (51)Cr to determine posttransfusion PLT recoveries and survivals. PLT morphology score, pH, hypotonic shock response, extent of shape change, and annexin V binding were determined just before transfusion. There were no differences in posttransfusion autologous radiolabeled PLT recoveries and survivals or in the in vitro measurements for the PLTs maintained at 22 degrees C versus those warmed to 35 degrees C using any of the three methods of PLT warming before infusion. Based on these 5-day-stored autologous radiolabeled PLT recovery and survival measurements, there is no evidence that warming PLTs to 35 degrees C before infusion improves postinfusion PLT viability.

Comparison of the in vitro properties of apheresis platelets during 7-day storage after interrupting agitation for one or three periods

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. 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. 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. 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.