Platelet concentrates prepared after a 20- to 24-hour hold of the whole blood at 22°C

BACKGROUND: The Food and Drug Administration (FDA) requires that red blood cells must be refrigerated within 8 hours of whole blood collection. Longer storage of whole blood at 22°C before component preparation would have many advantages. STUDY DESIGN AND METHODS: Two methods of holding whole blood for 20 to 24 hours at room temperature were evaluated, refrigerated plates or a 23°C incubator. After extended whole blood storage, platelet (PLT) concentrates were prepared from PLT‐rich plasma on Day 1 postdonation, and the PLTs were stored for 6 more days. On Day 7 of PLT storage, blood was drawn from each subject to prepare fresh PLTs. The stored and fresh PLTs were radiolabeled and transfused into their donor. RESULTS: Eleven subjects' whole blood was stored using refrigerated butanediol plates (Compocool, Fresenius), and 10 using an incubator. Poststorage PLT recoveries averaged 47 ± 13% versus 53 ± 11% and survivals averaged 4.6 ± 1.7 days versus 4.7 ± 0.9 days for Compocool versus incubator storage, respectively (p = NS). With all results, poststorage PLT recoveries averaged 75 ± 10% of fresh and survivals 57 ± 13% of fresh; PLT recoveries met FDA guidelines for poststorage PLT viability but not survivals. CONCLUSION: Seven‐day poststorage PLT viability is comparable when whole blood is stored for 22 ± 2 hours at 22°C using either refrigerated plates or an incubator to maintain temperature before preparing PLT concentrates.     

Extended storage of platelet‐rich plasma–prepared platelet concentrates in plasma or Plasmalyte

BACKGROUND: 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. STUDY DESIGN AND METHODS: 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 ⁵¹chromium or ¹¹¹indium, and in vitro measurements were performed on the stored PLTs. RESULTS: 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. CONCLUSION: There is a progressive decrease in recoveries and survivals of plasma‐stored PLTs over time. PLT viability is better maintained in plasma than Plasmalyte.     

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

BACKGROUND: Three of four prior studies suggested that warming platelets (PLTs) to 37°C before transfusion into patients with thrombocytopenia gave improved corrected PLT count increments.
STUDY DESIGN AND METHODS: Eighteen normal subjects had apheresis PLTs collected that were stored at 22°C for 5 days in two storage bags. One bag of PLTs was warmed to 35°C before infusion, and one remained at 22°C. Three different methods of warming the donor's autologous PLTs before reinfusion were evaluated: warming PLTs to 35°C for 10 or 60 minutes followed by radiolabeling or radiolabeling the PLTs followed by warming to 35°C for 60 minutes. In the first two methods, the warmed PLTs would have returned to 22°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 ¹¹¹In or ⁵¹Cr 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.
RESULTS: There were no differences in posttransfusion autologous radiolabeled PLT recoveries and survivals or in the in vitro measurements for the PLTs maintained at 22°C versus those warmed to 35°C using any of the three methods of PLT warming before infusion.
CONCLUSION: Based on these 5-day-stored autologous radiolabeled PLT recovery and survival measurements, there is no evidence that warming PLTs to 35°C before infusion improves postinfusion PLT viability.     

A randomized controlled trial comparing autologous radiolabeled in vivo platelet (PLT) recoveries and survivals of 7-day-stored PLT-rich plasma and buffy coat PLTs from the same subjects

BACKGROUND: A recent review concluded that there was inadequate evidence to show a difference between buffy coat (BC) and platelet (PLT)‐rich plasma (PRP) PLT concentrates prepared from whole blood. We hypothesized that 7‐day‐stored BC‐PLTs would have superior autologous recoveries and survivals compared to PRP‐PLTs and that both would meet the Food and Drug Administration (FDA) criteria for poststorage viability. STUDY DESIGN AND METHODS: This was a randomized, crossover study design in healthy subjects who provided informed consent. Each participant donated a unit of whole blood on two occasions. In random order, either BC‐PLTs or PC‐PLTs were prepared after a 20 ± 2°C overnight hold of the whole blood. PLTs were stored under standard conditions. On Day 7, fresh PLTs were prepared from 43 mL of autologous whole blood. The fresh PLTs paired with either BC‐PLTs or PRP‐PLTs were alternately labeled with ¹¹¹In or ⁵¹Cr and simultaneously reinfused to determine recoveries and survivals. In vitro assays were performed on Days 1 and 7. RESULTS: Fourteen subjects completed the study at two sites. No differences in poststorage PLT viabilities were observed between BC‐PLTs and PRP‐PLTs; recovery differences averaged 3.7 ± 2.4% (±SE, p = 0.15) and survival differences averaged 0.48 ± 0.56 days (p = 0.41). Neither type of PLTs met the current FDA criteria for either poststorage PLT recoveries or survivals. CONCLUSION: We were unable to demonstrate that single‐unit BC‐PLTs stored for 7 days have superior poststorage viability compared to PRP‐PLTs. Failure to meet the minimum FDA criteria for poststorage PLT viability raises questions regarding the acceptance thresholds of these metrics.     

Evaluation of the automated collection and extended storage of apheresis platelets in additive solution

BACKGROUND: Collecting apheresis platelets (PLTs) into additive solution has many potential benefits. The new Trima software (Version 6.0, CaridianBCT) allows automated addition of PLT additive solution (PAS) after collection, compared to Trima Version 5.1, which only collects PLTs into plasma. The aim of this study was to compare PLT quality during extended storage, after collection with the different Trima systems. STUDY DESIGN AND METHODS: Apheresis PLTs were collected using both Trima Accel apheresis systems. The test PLT units (n = 12) were collected using the new Trima Version 6.0 into PLT AS (PAS‐IIIM), while the control units (n = 8) were collected into autologous plasma using Trima Version 5.1. All units were stored for 9 days, and in vitro cell quality variables were evaluated during this time. RESULTS: PLTs collected in PAS‐IIIM maintained a stable pH between 7.2 and 7.4, whereas plasma‐stored apheresis units exhibited significantly increased acidity during storage, due to lactate accumulation and bicarbonate exhaustion. Plasma‐stored PLTs also demonstrated a more rapid consumption of glucose. However, there was little difference in PLT activation or cytokine secretion between PAS‐IIIM and control PLTs. CONCLUSION: These data indicate that apheresis PLT concentrates collected in PAS‐IIIM, using Trima Version 6.0 software, maintained acceptable PLT metabolic and cellular characteristics until Day 9 of storage.     

Preparation and storage of white blood cell-reduced split apheresis platelet concentrates for pediatric use

BACKGROUND: White blood cell (WBC) reduction and bacterial screening induce unacceptable product loss when platelet (PLT) concentrates (PCs) for pediatric transfusion are prepared from whole blood. The aim was to investigate PCs, WBC reduced and bacterially screened, from single-donor apheresis procedures, divided in 3 or 4 pediatric units and stored up to 5 days. STUDY DESIGN AND METHODS: PCs were collected with an apheresis machine and WBC reduced by in-process filtration. The PCs were sampled for bacterial screening and subsequently divided in 70-mL products. Initially, storage characteristics of split units in 400-mL polyvinylchloride (PVC) bags with 17 split PCs originating from five apheresis donations were studied. When a 600-mL container made of the more gas-permeable polyolefin became available, a paired comparison was performed with 9 split PCs from nine donations and with a higher-yield PLT collection procedure. RESULTS: Split PCs contained 69 x 10(9) +/- 14 x 10(9) PLTs in 69 +/- 1 mL of plasma, and storage in the PVC containers gave a pH value of 6.86 +/- 0.10 on Day 6 (mean +/- SD, n = 17). When comparing the containers, the PVC bag contained 98 x 10(9) +/- 15 x 10(9) PLTs in 72 +/- 4 mL versus 102 x 10(9) +/- 18 x 10(9) PLTs in 74 +/- 8 mL for the polyolefin bag (n = 9, not significant). This gave pH values on Day 6 of 6.12 +/- 0.50 in the PVC container, whereas pH remained acceptable in the polyolefin container: 6.85 +/- 0.10 on Day 6 (p < 0.01). CONCLUSION: PCs for pediatric use from split single-donor apheresis concentrates, WBC reduced and bacterially screened, can be stored for up to 5 days in a 600-mL polyolefin container with maintenance of good in vitro storage variables.     

In vitro and in vivo evaluation of apheresis platelets stored for 5 days in 65% platelet additive solution/35% plasma

BACKGROUND: In the United States, apheresis platelets (PLTs) are suspended in autologous plasma. PLT additive solutions, long used in Europe, decrease recipient allergic reactions and may reduce the risk of transfusion‐related acute lung injury. We evaluated Amicus‐collected PLTs stored in platelet additive solution (PAS) III (InterSol) for 5 days. STUDY DESIGN AND METHODS: In Study 1, 71 subjects donated two products on a single day—one each stored in 100% plasma or 65% PAS III/35% plasma. Products underwent standard in vitro testing on Days 1 and 5. In Study 2, 43 additional subjects provided Amicus products stored for 5 days in 65% PAS III/35% plasma for in vivo radiolabeled recovery and survival determinations. The effect of approximately 2500 cGy Day 1 gamma irradiation was evaluated in a subset of products. RESULTS: PAS III PLTs (n = 70) had a median Day 5 pH_22°C of 7.2 (lower 95%, 95% tolerance limit, 6.9). Mean Day 5 recovery and survival of radiolabeled PAS III PLTs (n = 33) were, respectively, 80.5 and 72.1%, of fresh autologous PLTs. With 95% confidence, these values were at least 66% of fresh PLT recovery and 58% of survival. All in vitro variables remained within ranges seen in licensed products for irradiated and nonirradiated PAS III PLTs. CONCLUSION: Leukoreduced Amicus PLTs stored in 65% PAS III/35% plasma in PL‐2410 containers maintained pH ≥ 6.9 throughout 5 days' storage. Radiolabeled PLT recovery and survival values met US Food and Drug Administration statistical criteria. Gamma‐irradiated PAS III PLTs demonstrated no significant adverse effects due to irradiation in in vitro testing.     

Further evaluation of a new standard of efficacy for stored platelets

BACKGROUND: The proposal to assess the viability capabilities of platelets (PLTs) collected, treated, or stored in a developmental system against "fresh" PLTs from the same subject poses several important methodologic issues pertaining to the timing and manner of the collecting and separating the fresh PLTs. This study extended the previous validation of this method of comparing fresh and stored PLTs, applying it to an assessment of apheresis PLTs stored for 7 days with a newly standardized radiolabeling protocol. STUDY DESIGN AND METHODS: Eighteen normal subjects donated 1 unit of leukoreduced PLTs, pheresed with a standard, approved system. They received an aliquot radiolabeled with 51Cr on Day 7 simultaneously with 111In-labeled fresh PLTs that had been separated by a manual method. Recovery and survival were compared to determine whether the stored PLTs were not inferior to the criterion of 67 percent of recovery and 50 percent of survival of fresh PLTs. Separate studies were undertaken to document the similarity of recovery and survival with 51Cr and 111In radiolabeling in PLTs stored to 8 days and to determine the importance of correcting the radioactivity in timed samples for the activity remaining in blood beyond the life span of the retransfused PLTs. RESULTS: PLTs stored for 7 days demonstrated 88.7 +/- 35.2 percent of the recovery and 89.9 +/- 21.2 percent of the survival of PLTs collected via a nonproprietary, manual system and thus met the comparative criterion. In a separate study (n = 12), labeling Day 8 PLTs with 51Cr or 111In resulted in recoveries and survivals that were not different. Radiolabel eluted from labeled PLTs in vitro was taken up by cellular blood elements in a reuptake incubation. CONCLUSION: Apheresis PLTs stored for 7 days met the criterion proposed for comparison with fresh PLTs. This analytic approach is feasible with PLTs collected and prepared via a manual method. A standardized protocol for radiolabeling PLTs with 51Cr and 111In and analyzing the results in a standardized fashion was employed successfully, with the two radioisotopes yielding similar results. The importance of correcting for residual activity after disappearance of injected cells was noted.     

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

BACKGROUND: 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. STUDY DESIGN AND METHODS: 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. RESULTS: 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%. CONCLUSION: 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.     

Paired in vitro and in vivo comparison of apheresis platelet concentrates stored in platelet additive solution for 1 versus 7 days

BACKGROUND: To improve clinical access to platelet concentrates (PCs), prolonging the storage period is one alternative, provided that they are free from bacteria. The quality of platelets (PLTs) stored for 1 versus 7 days was compared by in vitro analyses and in vivo recovery and survival in blood donors. STUDY DESIGN AND METHODS: Apheresis PCs from 10 donors were divided and stored in PLT additive solution in 2 equal units for a paired comparison. PLTs in one unit were (111)In-labeled at 1 day of storage, and PLTs in the other unit were labeled after 7 days of storage. PLTs were injected into the donor after labeling and samples were drawn after 30, 60, and 150 minutes and thereafter once a day for 14 days for recovery and survival measurements. RESULTS: PLT recovery on Day 7 was 80 percent of the recovery on Day 1 (p<0.05), and the survival on Day 7 was 65 percent of survival on Day 1 (p<0.005). No significant differences were seen regarding mean PLT volume (MPV), pH, pCO2, pO2, bicarbonate, or hypotonic shock response. Lactate increased and lactic dehydrogenase increased slightly, whereas glucose and ATP decreased, but not to a critical level. A significant increase in RANTES (110.7+/-76.6 vs. 277.6+/-50.8 pg/10(6) PLTs [p<0.005]) and PLT factor 4 (19.9+/-9.6 vs. 59.8+/-7.5 IU/10(6) PLTs [p<0.0001]) was noticed during storage. CONCLUSION: Recovery and survival of PCs stored for 7 days decreased, but met suggested criteria. Analyzed in vitro parameters showed acceptable results. Randomized patient transfusion studies will provide additional verification of the suitability of 7-day storage of PLTs.     

Autologous transfusion recovery of WBC-reduced high-concentration platelet concentrates

BACKGROUND: This study evaluates the recovery and survival of high-concentration platelets (HCPs) compared to standard apheresis platelets (APCs) in a double-label autologous human system. METHODS: Nine HCP units paired with APC units were stored, labeled with either 51Cr and 111In, and returned, and recovery and survival were determined. Standard in vitro platelet biochemical and functional parameters were monitored over the storage period and evaluated in a secondary analysis. RESULTS: Three each HCP units containing more than 2.2 x 10(11), 1.5 x 10(11) to 2.1 x 10(11), and 0.8 x 10(11) to 1.1 x 10(11) platelets in 59.4 +/- 2.5 mL were stored for 1, 2, or 5 days, respectively, and simultaneously with matched APC units (3.8 x 10(11) platelets, 282 mL). Recoveries were 72.3 +/- 8.6, 60.8 +/- 14.6, and 52.5 +/- 6.7 percent for HCPs, respectively; and 59.4 +/- 6.4 percent for APCs (p=0.37). HCP survivals were 202.0 +/- 14.9, 204.9 +/- 10.2, and 162.6 +/- 17.0 hours; APC survivals were 155.4 +/- 20.3 hours (p=0.001). Secondary analysis with P-selectin added as a predictor in the model resulted in significant difference in recoveries for Day 1 HCPs versus Day 5 APCs (p=0.024) with no difference shown for HCPs on Days 2 or 5 versus APCs. No significant difference was found in survival (p=0.16). CONCLUSION: HCPs may be stored 24 hours for high yield, 48 hours for intermediate yield, and up to 5 days for yields less than 1.6 x 10(11) platelets per bag with equivalent to superior recovery and survival of platelets in the autologous transfusion model compared to APCs.     

Platelets photochemically treated with amotosalen HCl and ultraviolet A light correct prolonged bleeding times in patients with thrombocytopenia

BACKGROUND: Photochemical treatment (PCT) with amotosalen HCl with ultraviolet A illumination inactivates pathogens and white blood cells in platelet (PLT) concentrates. STUDY DESIGN AND METHODS: In a Phase II crossover study, 32 patients with thrombocytopenia received one transfusion of PCT and/or one transfusion of untreated (reference) apheresis PLTs. Hemostatic efficacy was assessed with the cutaneous template bleeding time and clinical observations. RESULTS: Paired bleeding time data for PCT and reference transfusions were available for 10 patients. Mean pretransfusion bleeding times were 29.2 +/- 1.6 minutes in the PCT group and 28.7 +/- 2.5 minutes in the reference group. After transfusion of a dose of PLTs of at least 6.0 x 10(11), mean 1-hour posttransfusion template bleeding times corrected to 19.3 +/- 9.5 minutes in the PCT group and 14.3 +/- 6.5 minutes in the reference group (p = 0.25). In 29 patients receiving paired PCT and reference transfusions, mean 1-hour posttransfusion PLT count increments were 41.9 x 10(9) +/- 20.8 x 10(9) and 52.3 x 10(9) +/- 18.3 x 10(9) per L for PCT and reference, respectively (p = 0.007), and mean 1-hour posttransfusion PLT corrected count increments (CCIs) were 10.4 x 10(3) +/- 4.9 x 10(3) and 13.6 x 10(3) +/- 4.3 x 10(3) for PCT and reference, respectively (p < 0.001). The time to next PLT transfusion was 2.9 +/- 1.2 days after PCT transfusions versus 3.4 +/- 1.3 days after reference transfusions (p = 0.18). Clinical hemostasis was not significantly different after PCT and reference transfusions. CONCLUSION: PCT PLTs provided correction of prolonged bleeding times and transfusion intervals not significantly different than reference PLTs despite significantly lower PLT count increments and CCIs.     

Efficacy of apheresis platelets treated with riboflavin and ultraviolet light for pathogen reduction

BACKGROUND: Pathogen reduction technologies for platelet (PLT) components offer a means to address continued viral transmission risks and imperfect bacterial detection systems. The efficacy of apheresis PLTs treated with riboflavin (vitamin B2) plus ultraviolet (UV) light (Mirasol, Navigant Biotechnologies) was investigated in a single-blind, crossover study in comparison to untreated PLTs. STUDY DESIGN AND METHODS: Normal subjects (n = 24) donated PLTs by apheresis on two occasions at least 2 weeks apart. Units were randomized to control or test arms, the latter receiving the addition of 28 mL of 500 micromol per L B2 and exposure to 6.2 J per mL UV light. PLTs were stored for 5 days with biochemical and hematologic analyses performed before and after illumination on Day 0 and at the end of storage. An aliquot of each unit was radiolabeled and returned to determine recovery and survival. RESULTS: The PLT content of treated units was maintained from Day 0 (4.1 x 10(11) +/- 0.4 x 10(11)) to Day 5 (4.0 x 10(11) +/- 0.4 x 10(11)). Treatment with B2 plus UV light was associated with an increase in lactate production with concomitant increases in glucose consumption. pH (control, 7.38 +/- 0.07; test, 7.02 +/- 0.10) was well maintained throughout storage. Recovery of treated PLTs (50.0 +/- 18.9%) was reduced from that of control PLTs (66.5 +/- 13.4%); survival was similarly shortened (104 +/- 26 hr vs. 142 +/- 26 h; p < 0.001). CONCLUSIONS: PLTs treated with B2 plus UV light demonstrate some alterations in in vitro measures but retain in vitro and in vivo capabilities similar to pathogen-reduced and licensed PLT components that have been shown to have useful clinical applicability. The recovery, survival, and metabolic properties of Mirasol PLTs should provide sufficient hemostatic support in thrombocytopenia to justify patient clinical trials.     

Quantitation of coated platelet potential during collection, storage, and transfusion of apheresis platelets

BACKGROUND: Coated platelets (PLTs), a subpopulation of PLTs observed upon dual agonist stimulation with collagen and thrombin, are known to retain several procoagulant α‐granule proteins on their surface. By formation of a highly active membrane‐bound prothrombinase complex, these PLTs represent an important step in the coagulation cascade as a consequence of their ability to generate thrombin at the site of vascular injury. Various clinical observations suggest that higher levels of coated PLTs are associated with thrombosis while a deficiency of coated PLTs results in a bleeding diathesis. Current quality control guidelines for in vitro PLT storage measure PLT viability but no routine evaluation of the hemostatic function of stored PLTs and particularly no estimation of coated PLT potential is performed. Our primary objective was to evaluate if the process of apheresis and storage of PLT units alters the levels of coated PLTs. In addition, we sought to determine how transfusion of stored PLTs into patients with thrombocytopenia affects the patient's coated PLT levels. STUDY DESIGN AND METHODS: Coated PLT levels were analyzed in 13 voluntary PLT donors before donation, in the fresh apheresis product (Trima, CaridianBCT) and in the stored apheresis product just before transfusion. In addition, 10 patients with thrombocytopenia were analyzed for coated PLTs before and after transfusion of a stored PLT product. RESULTS: Coated PLT levels were significantly decreased after the process of apheresis (17% relative decline; p < 0.01) and with prolonged storage (1 to 5 days; 53% relative decline; p < 0.001). Transfusion of stored PLT units did not result in significant increment of coated PLT levels in patients with thrombocytopenia as expected considering the low level of coated PLTs in stored PLT units. Furthermore, there was no suggestion of regeneration of coated PLT potential upon reinfusion. CONCLUSIONS: Isolation and storage of apheresis PLTs by standard blood bank procedures results in a significant decline in coated PLT potential. Reinfusion of stored apheresis PLTs into patients with thrombocytopenia resulted in a predictable change in coated PLT potential with no suggestion of regeneration of lost coated PLT potential.     

Leukoreduced buffy coat-derived platelet concentrates photochemically treated with amotosalen HCl and ultraviolet A light stored up to 7 days: assessment of hemostatic function under flow conditions

BACKGROUND: Amotosalen plus ultraviolet A light photochemical treatment (PCT) inactivates high titers of bacteria, and other pathogens, in platelet concentrates (PCs) potentially allowing the storage of platelets (PLTs) for up to 7 days. Adhesion and aggregation of PLTs to injured vascular surfaces are critical aspects of PLT hemostatic function. STUDY DESIGN AND METHODS: Two ABO-identical leukoreduced buffy coat-derived PCs in additive solution were mixed and divided: one-half underwent PCT (PCT-PCs) and the other was kept as a control (C-PCs); both were stored under standard conditions. The total number of paired PCs studied was nine. Samples were taken on Day 1 (before PCT) and after 5 and 7 days of storage. The adhesion and aggregation capacities were evaluated under flow conditions in a ex vivo perfusion model. RESULTS: Compared to control, PCT resulted in a decrease in PLT count of 6.5 percent (p = 0.004) and 10.2 percent (p = 0.008) after 5 and 7 days' storage, respectively (n = 9). PLT interaction with subendothelium was mainly in form of adhesion. The surface covered by PCT PLTs on Day 1 was 26.0 +/- 4.2 percent (mean +/- SEM). On Day 5, PCT-PCs showed a covered surface of 20.9 +/- 2.2 percent, and the C-PCs, 20.6 +/- 1.6 percent. After 7 days, PCT-PCs produced a nonsignificant higher PLT deposition compared to control (27.1 +/- 2.9% vs. 21.2 +/- 2.8%, p = 0.06). CONCLUSION: PCT of PCs and storage up to 7 days was associated with a 10.2 percent decrease in PLT count due to processing losses compared to C-PC. PLT adhesive and aggregating capacities under flow conditions of PCT-PCs were similar to C-PCs and remained well preserved for up to 7 days of storage.     

Maintenance of storage properties of pediatric aliquots of apheresis platelets in fluoroethylene propylene containers

BACKGROUND: Platelet (PLT) aliquots for pediatric use have been shown to retain in vitro properties when stored in gas‐impermeable syringes for up to 6 hours. As an alternative, PLT aliquots can be stored for longer periods in containers used for storage of whole blood–derived PLTs. These containers are not available separate from whole blood collection sets and PLT volumes less than 35 mL either have not been evaluated or may be unsuitable for PLT storage. Gas‐permeable fluoroethylene propylene (FEP) containers have been used in the storage of cell therapy preparations and are available in multiple sizes as single containers but have not been evaluated for PLT storage. STUDY DESIGN AND METHODS: A single apheresis unit was divided on Day 3 into small aliquots with volume ranging from 20 to 60 mL, transferred using a sterile connection device, and stored for an additional 2 days either in CLX (control) or in FEP containers. PLT storage properties of PLTs stored in FEP containers were compared to those stored in CLX containers. Standard PLT in vitro assays were performed (n = 6). RESULTS: PLT storage properties were either similar to those of CLX containers or differed by less than 20% excepting carbon dioxide levels, which varied less than 60%. CONCLUSION: Pediatric PLT aliquots of 20, 30, and 60 mL transferred on Day 3 into FEP cell culture containers adequately maintain PLT properties for an additional 2 days of storage.     

Effects of Mirasol PRT treatment on storage lesion development in plasma-stored apheresis-derived platelets compared to untreated and irradiated units

BACKGROUND: The aim of this study was to examine the effects of a new riboflavin-based pathogen reduction technology (PRT), the Mirasol PRT process (Navigant Biotechnologies) on platelet (PLT) storage lesion development. STUDY DESIGN AND METHODS: A three-arm in vitro study was conducted comparing cell quality of apheresis PLTs (n = 12 each) treated with Mirasol PRT (M) to untreated (C) and gamma-irradiated units (X) collected from the same donors and stored for up to 7 days under equal conditions. RESULTS: PLT count, lactate dehydrogenase, and K+ release of M units were not significantly different from C units, indicating retention of cell integrity during storage. The immediate effect (Day 1) of PRT treatment was a significant decrease in hypotonic shock response (M, 80.6 +/- 7.8% vs. 89.2 +/- 8.3%) and aggregation (M, 85.7 +/- 15.2%/min vs. 111.8 +/- 31.5%/min) as well as a significant acceleration of mitochondrial membrane depolarization (M, 1.43 +/- 0.44% vs. 0.91 +/- 0.27%) and P-selectin expression (M, 38.4 +/- 13.8% vs. 15.8 +/- 7.7%) resulting in lower swirl scores on Day 5 (1.5 +/- 0.7 vs. 2.7 +/- 0.4). Significantly higher glucose consumption (60 +/- 13 nmol/10(12) cells/hr vs. 31 +/- 9 nmol/10(12) cells/hr) and lactate production rates (82 +/- 17 nmol/10(12) cells/hr vs. 40 +/- 8 nmol/10(12) cells/hr) caused higher acidity in treated units (pH on Day 5, 6.97 +/- 0.15 vs. 7.42 +/- 0.10). After PRT treatment, oxidative metabolism was still active and, from calculation of oxygen consumption (1.09 +/- 0.23 nmol/min/10(9) PLTs), appeared to be up regulated relative to controls (0.76 +/- 0.27 nmol/min/10(9) PLTs). CONCLUSION: Although storage variables clearly showed the effects of PRT treatment, apheresis PLTs treated with Mirasol PRT retained cell quality during 5 days of storage without loss of mitochondria-based oxidative respiration.     

Pathogen inactivation of platelets using ultraviolet C light: effect on in vitro function and recovery and survival of platelets

BACKGROUND: We evaluated the effect of treating platelets (PLTs) using ultraviolet (UV)C light without the addition of any photosensitizing chemicals on PLT function in vitro and PLT recovery and survival in an autologous radiolabeled volunteer study. STUDY DESIGN AND METHODS: For in vitro studies, pooled or single buffy coat–derived PLT concentrates (PCs) were pooled and split to obtain identical PCs that were either treated with UVC or untreated (n = 6 each) and stored for 7 days. PLT recovery and survival were determined in a two‐arm parallel autologous study in healthy volunteers performed according to BEST guidelines. UVC‐treated or untreated PCs (n = 6 each) were stored for 5 days and were compared to fresh PLTs from the same donor. RESULTS: There were no significant differences on Day 7 of storage between paired UVC‐treated and control PC units for pH, adenosine triphosphate, lactate dehydrogenase, CD62P, CD63, PLT microparticles, and JC‐1 binding, but annexin V binding, lactate accumulation, and expression of CD41/61 were significantly higher in treated units (p < 0.05). Compared with control units, the recovery and survival of UVC‐treated PC were reduced after 5 days of storage (p < 0.05) and when expressed as a percentage of fresh values, survival was reduced by 20% (p = 0.005) and recovery by 17% (p = 0.088). CONCLUSION: UVC‐treated PLTs stored for 5 days showed marginal changes in PLT metabolism and activation in vitro and were associated with a degree of reduction in recovery and survival similar to other pathogen inactivation systems that are licensed and in use.     

Functional characteristics of buffy-coat PLTs photochemically treated with amotosalen-HCl for pathogen inactivation

BACKGROUND: One blood system for PLTs (INTERCEPT, Baxter Transfusion Therapies) is based on photochemical treatment (PCT) with small molecules that target cross-link nucleic acids (Helinx technology, Cerus Corp.) with amotosalen-HCl (S-59) and UVA light (320-400 nm) to inactivate pathogens and WBCs. STUDY DESIGN AND METHODS: A two-arm in vitro study was conducted to compare pooled buffy-coat-derived PLT concentrates (PCs) treated with the INTERCEPT blood system, resuspended in PLT additive solution (PAS) III (InterSol, Baxter Transfusion Therapies), and stored for up to 7 days (test units, n = 20) with unpaired, nontreated PCs, resuspended in PAS II (T-Sol, Baxter Transfusion Therapies), and prepared at the same center in the same manner (control units, n = 18). RESULTS: PLT dose (x 1011/unit +/- SD) on Day 1 immediately following PCT was 3.0 +/- 0.4 for test units and 3.2 +/- 0.4 for control units. After 7 days of storage, the pH of all test units was maintained above 6.8. No marked trend was observed in the hypotonic shock response (HSR). Values among study groups were similar at the end of observation period: 68 +/- 11 percent for control unites versus 67 +/- 8 percent for test units (p > 0.05). Aggregation response to ristocetin was slightly lower in test units: at Day 7, 65 +/- 10 percent versus 76 +/- 6 percent (p < 0.05). Significantly higher (p < 0.001) glucose consumption, lactate production, and CD62P expression were observed in test units. CONCLUSION: Compared to nontreated PLTs, the PCT process was associated with a variety of differences of in vitro analyses. Although significant, these changes were relatively small in most cases. Characteristics correlated with survival in vivo such as HSR and swirling were comparable between both study groups, indicating that the viability of the majority of cells appears to have persisted throughout 7 days of storage. The impact of this finding, however, remains to be investigated in clinical trials performed with 7-day stored PLTs.     

Recovery, survival, and function of transfused platelets and detection of platelet engraftment after allogeneic stem cell transplantation

BACKGROUND: Recovery and survival of transfused platelets (PLTs) are usually assessed by radioisotope labeling methods for evaluation of transfusion efficacy and new progress in the processing of PLT concentrates. Alternative, nonradioactive methods are warranted. STUDY DESIGN AND METHODS: A multicolor flow cytometry method was developed for simultaneous studies of recovery, survival, and function of transfused PLTs. Eight consecutive patients undergoing allogeneic stem cell transplantation (TX) were transfused with apheresis PLTs of nonself human leukocyte antigen (HLA) Class I types, and HLA Class I discrepancy between donor and recipient was used to identify transfused PLTs. Hematologic status and HLA Class I surface expression were analyzed immediately before transfusion, 1 and 6 hours after transfusion, and daily during the subsequent week. PLT activation was assessed by surface expression of CD63, CD62P, or CD42a, before and after stimulation with thrombin receptor agonist peptide. RESULTS: PLT recovery was 43, 41, and 31% for fresh (5‐72 hr old) and 30, 27, and 17% for stored (73‐148 hr old) PLTs, after 1, 6, and 15 to 28 hours, respectively. Survival of fresh versus stored PLTs were 160 and 105 hours, respectively. Spontaneous PLT activation and residual activation potential were almost equal for fresh and stored PLTs. PLT engraftment was detected between Day 7 and Day 9, which was significantly earlier than first sign of neutrophil engraftment (Days 11‐19; p = 0.01). CONCLUSION: Flow cytometry is an attractive alternative to radiolabeling of PLTs for simultaneous studies of survival, recovery, and function of transfused PLTs and early detection of PLT engraftment after allogeneic stem cell TX.