Extended storage of platelets in a new plastic container. II. In vivo response to infusion of platelets stored for 5 days

Effect of Recombinant Human Perlecan Domain V Tethering Method on Protein Orientation and Blood Contacting Activity on Polyvinyl Chloride

Surface modification of biomaterials is a promising approach to control biofunctionality while retaining the bulk biomaterial properties. Perlecan is the major proteoglycan in the vascular basement membrane that supports low levels of platelet adhesion but not activation. Thus, perlecan is a promising bioactive for blood-contacting applications. This study furthers the mechanistic understanding of platelet interactions with perlecan by establishing that platelets utilize domains III and V of the core protein for adhesion. Polyvinyl chloride (PVC) is functionalized with recombinant human perlecan domain V (rDV) to explore the effect of the tethering method on proteoglycan orientation and bioactivity. Tethering of rDV to PVC is achieved via either physisorption or covalent attachment via plasma immersion ion implantation (PIII) treatment. Both methods of rDV tethering reduce platelet adhesion and activation compared to the pristine PVC, however, the mechanisms are unique for each tethering method. Physisorption of rDV on PVC orientates the molecule to hinder access to the integrin-binding region, which inhibits platelet adhesion. In contrast, PIII treatment orientates rDV to allow access to the integrin-binding region, which is rendered antiadhesive to platelets via the glycosaminoglycan (GAG) chain. These effects demonstrate the potential of rDV biofunctionalization to modulate platelet interactions for blood contacting applications.

Hexamoll DINCH plasticised PVC containers for the storage of platelets

Introduction:

Containers for the storage of platelets are made using polyvinyl chloride plasticised with di, (2-ethyl hexyl) phthalate, n-butyryl, tri (n-hexyl) citrate and tri (2-ethyl hexyl) mellitate or using special poly olefins without plasticiser. Of these, the first two have disadvantages such as plasticiser leaching and impairment of platelet function. Polyolefin bags cannot be HF welded or steam sterilized. Mellitate plasticised bags can store platelets well for five days but they are not completely phthalate free.

Research and Development:

We have developed a new generation of containers made of PVC plasticised with the non DEHP, non aromatic plasticiser,1,2- Cyclohexanedicarboxylic acid, diisononyl ester (Hexamoll DINCH) which can store platelets without loss of function for at least six days.

Observation:

The present studies show that DINCH plasticised PVC bags (TPL-167) are well suited for the storage of platelet concentrates for more than five days.

Conclusion:

The present studies show that the PVC plasticised with the non phthalate, non aromatic, non toxic plasticiser DINCH is a viable alternative to other existing containers for the storage of platelets for more than five days.

Preparation of platelet concentrates

Platelets are specialized blood cells that play central roles in physiologic and pathologic processes of hemostasis, wound healing, host defense, thrombosis, inflammation, and tumor metastasis. Activation of platelets is crucial for platelet function that includes a complex interplay of adhesion, signaling molecules, and release of bioactive factors. Transfusion of platelet concentrates is an important treatment component for thrombocytopenia and bleeding. Recent progress in high-throughput mRNA and protein profiling techniques has advanced the understanding of platelet biological functions toward identifying novel platelet-expressed and secreted proteins, analyzing functional changes between normal and pathologic states, and determining the effects of processing and storage on platelet concentrates for transfusion. It is important to understand the different standard methods of platelet preparation and how they differ from the perspective for use as research samples in clinical chemistry. Two simple methods are described here for the preparation of research-scale platelet samples from whole blood, and detailed notes are provided about the methods used for the preparation of platelet concentrates for transfusion.

Past and Future Approaches to Assess the Quality of Platelets for Transfusion

No automated test exists to routinely measure platelet quality. Currently, the short, 5-day shelf life of platelet concentrates is largely dictated by the risk associated with bacterial contamination and not by platelet quality. With the implementation of bacterial testing and pathogen inactivation, platelet quality will become the major determinant for the shelf life of platelet concentrates. However, extended use of platelet concentrates stored beyond 5 days will require quality testing. In addition, high platelet quality would be expected to result in improved clinical efficacy, determined by count increment, improved hemostasis, and lower risk for adverse reactions in recipients. No in vitro quality test has yet demonstrated a good correlation with clinical efficacy or improved hemostasis. This review focuses on those tests of platelet quality that are based on platelet morphology. These include visual inspection of swirling, microscopic morphology score, measurement of light transmission through platelet concentrates, and platelet light scattering techniques. Recently, a new test for platelet quality has been introduced that uses dynamic light scattering. The advantages and remaining challenges for dynamic light scattering before it can become a routine platelet quality test are discussed.

Recovery and life span of 111 indium-radiolabeled platelets treated with pathogen inactivation with amotosalen HCl (S-59) and ultraviolet A light

BACKGROUND

A photochemical treatment (PCT) method to inactivate pathogens in platelet concentrates has been developed. The system uses a psoralen, amotosalen HCl, coupled with ultraviolet A (UVA) illumination.

STUDY DESIGN AND METHODS

Three sequential clinical trials evaluated viability of PCT platelets prepared with a prototype device. Posttransfusion recovery and lifespan of (111)Indium-labeled autologous 5 day-old platelets in healthy subjects was assessed. In the first study, 23 subjects received transfusions of autologous PCT and/or control platelets. In a second study, 16 of these subjects received PCT platelets processed with a Compound Adsorption Device (CAD) (PCT-CAD) to reduce patient exposure to residual amotosalen. In the third study, the effect of gamma-irradiation on PCT platelets was studied. Data from control transfusions from Study A were used for paired comparisons in the latter 2 studies.

RESULTS

Mean PCT-CAD platelet recovery for the 16 subjects with paired data was 42.5 +/- 8.7% versus 50.3 +/- 7.7% for control platelets, mean difference of 7.8% (p < 0.01). Mean lifespan for PCT-CAD platelets was 4.8 days (+/-1.3) versus 6.0 days (+/-1.2) for control platelets, mean difference of 1.3 days (p < 0.01). Platelet recovery and lifespan were similar to PCT-CAD for PCT without CAD treatment and PCT-CAD with gamma-irradiation.

CONCLUSION

Viability of 5 day-old PCT platelets was less than for control platelets. However, both were within ranges reported for 5 day-old platelets.

Triggers for prophylactic use of platelet transfusions and optimal platelet dosing in thrombocytopenic dogs and cats

Prophylactic platelet transfusions are frequently given to human patients with hypoproliferative thrombocytopenia. For several decades, the most common transfusion trigger was 20,000/microL, but the trend is now to use 10,000/microL in the absence of other risk factors for bleeding. This trigger seems to reduce the number of transfusions without increasing the risk of severe bleeding. Most studies involved in establishing platelet transfusion policies have involved patients with acute leukemia, with fewer studies involving patients undergoing hematopoietic stem cell transplantation or aggressive chemotherapy for other cancers and patients with aplastic anemia. In the presence of other risk factors for spontaneous bleeding, 20,000/microL is still considered an appropriate trigger. The trigger for prophylactic transfusion before surgery has not undergone the same recent scrutiny as has the trigger for spontaneous bleeding. The recommendation remains to raise the platelet count to 50,000 to 100,000/microL if possible, although it is recognized that surgery and other invasive procedures have been performed at lower platelet counts without major bleeding. Prophylactic transfusion is not used in disorders of platelet consumption and destruction to prevent spontaneous bleeding but is used before surgery. Because of the comparative lack of experience with platelet transfusion in veterinary medicine, it is difficult to make generalizations for dogs and cats. Using the guidelines established for therapeutic and prophylactic transfusion of human patients is a reasonable starting point, however. A therapeutic transfusion policy is suggested in the veterinary setting provided that the patient can be closely observed for critical bleeding and a prompt transfusion can be given. This policy should ultimately reduce the overall number of platelet transfusions given to hospital patients. If an animal cannot be closely observed or the ability to transfuse on demand is limited, prophylactic transfusion is recommended. The triggers for initiating a platelet transfusion in dogs are extrapolated from human data; these values are lower by 50% for cats. Because of the imprecision of platelet counting at low values, platelet counts must always be interpreted in conjunction with clinical signs of hemorrhage. If platelet-rich plasma or platelet concentrate is available, a dose of 1 platelet unit per 10 kg is recommended, although resources may dictate a smaller dose. This will raise the recipient platelet count by a maximum of about 40,000/microL. Assuming a trigger of 10,000/microL, a transfusion will probably be required approximately every 3 days. It must be remembered that the frequency of platelet transfusions may be greater in the presence of factors accelerating platelet loss or destruction. If fresh whole blood is used, a rule of thumb is to transfuse 10 mL/kg, which will raise the recipient platelet count by a maximum of approximately 10,000/microL. Daily transfusions or transfusions every other day will probably be required.

Apoptotic activity in stored human platelets

BACKGROUND

Platelets possess some of the machinery required for apoptotic cell death. However, disruption of mitochondria function, implicated in several models of cell death, has not been extensively studied in platelets. Mitochondrial viability and several other measures of apoptotic death in stored and experimentally stressed platelets were evaluated.

MATERIALS AND METHODS

Platelet mitochondrial transmembrane potentials (Deltapsim) were studied by staining platelets with JC-1, a dye that fluoresces at different wavelengths based on the state of mitochondrial polarization. Annexin V binding, a measure of phosphatidylserine (PS) exposure, and CD62P expression, an indicator of platelet activation, were determined by flow cytometry. Caspase-3 activity was measured with an enzyme assay and by Western blotting. Experimental platelet stressors included storage for 7 days, azide exposure, calcium ionophore stimulation, and plasma deprivation.

RESULTS

As measured by flow cytometry, Deltapsim values were similar in freshly drawn platelets and in platelet concentrates stored for up to 7 days. However, compared to fresh platelets, stored platelet concentrates had significantly increased PS exposure (3.1 vs. 5.1%, p = 0.015), CD62P expression (6.5 vs. 13.5%, p = 0.0067), and caspase-3 activity. Azide exposure, which decreased ATP release 20 to 30 percent, did not affect the Deltapsim. Stressed platelets exhibited higher degrees of mitochondrial depolarization in response to calcium ionophore stimulation than platelets that were not stressed. Plasma deprivation also resulted in significant alterations in Deltapsim, PS exposure, and CD62P expression.

CONCLUSIONS

Platelet mitochondria maintain Deltapsim when stored for up to 7 days under standard blood bank storage conditions. Therefore, changes in platelet mitochondria Deltapsim do not correlate with downstream markers of apoptotic death such as caspase activation and PS exposure.

A rabbit model for monitoring in vivo viability of human platelet concentrates using flow cytometry

BACKGROUND

Viability in vivo of novel platelet components cannot be readily determined in human transfusions. Elaboration of valid animal models may be useful for this purpose.

STUDY DESIGN AND METHODS

Viability of platelet concentrates (PCs) WBC reduced before storage was determined by flow cytometry in rabbits whose reticuloendothelial system was inhibited by ethyl palmitate administration. PCs stored at 22 degrees C for 2 and 5 days (D2- and D5-PCs) or refrigerated PCs (3-6 days at 22 degrees C plus 1-4 days at 4 degrees C, RF-PCs) were transfused into rabbits. Five parameters of PC viability in vivo were calculated from human platelet survival curves: survival time, recovery 0.5 and 24 hours after transfusion (R0.5, R24), maximal recovery (Rmax), and total recovery for 0 to 24 hours (RSigma).

RESULTS

No differences in viability of D2- and D5-PCs were found. In contrast, viability of RF-PCs was significantly lower than that of D2-PCs, as was revealed with diverse sensitivity by four parameters: RSigma > R24 > R0.5=survival time (p < 0.001, p < 0.01, and p < 0.05, respectively).

CONCLUSION

The rabbit model elaborated is sufficiently sensitive to reveal differences in human platelet viability in vivo between conventional and cold-damaged PCs. It may be useful for comparing viability of different platelet components that cannot be readily tested in human transfusions.

Algorithm for managing the platelet refractory patient

Refractoriness to platelet transfusions continues to be a major problem for many thrombocytopenic patients. A proposed algorithm for managing these patients is presented which proceeds from easily instituted changes in platelet transfusion therapy such as provision of ABO-compatible and "fresh" platelet transfusions to the more difficult and costly process of selecting compatible platelets for patients who are documented to be alloimmunized. For nonimmunized platelet refractory recipients, multiple clinical and drug factors that may adversely effect transfusion responses have been identified. Identifying which of these factors are causally associated with poor platelet responses in any given patient remains a substantial challenge.

Effect of recombinant human megakaryocyte growth and development factor coupled with polyethylene glycol on the platelet storage lesion

BACKGROUND

Platelet production is regulated by a thrombopoietic growth factor (Mpl ligand). The receptor for this platelet growth factor (Mpl) is expressed on the platelet surface membrane. A recombinant thrombopoietic cytokine, recombinant human megakaryocyte growth and development factor coupled with polyethylene glycol (PEG-rHuMGDF), was added to apheresis platelets in vitro to determine whether Mpl ligand-receptor binding produced any beneficial or adverse effect on the development of the platelet storage lesion during 5 days of storage.

STUDY DESIGN AND METHODS

This study was designed as a dose-response protocol to determine the effects of adding increasing concentrations of PEG-rHuMGDF (0.0 [control], 2.5, 25, and 250 ng/mL) to apheresis platelets stored in two types of plastic storage containers. The increasing concentrations of PEG-rHuMGDF used simulated the theoretical peak plasma level attained in vivo, with an intravenous dose of 0, 0.1, 1.0 and 10 microg per kg of PEG-rHuMGDF. The platelets were stored with agitation at 20 to 24 degrees C for 5 days. A battery of in vitro assays was performed on storage Days 1 and 5, including pH, blood gases, platelet count, lactate dehydrogenase, mean platelet volume, glucose, lactate, osmotic recovery, morphology score, CD62P, and one-dimensional polyacrylamide gel electrophoresis analyses.

RESULTS

Analysis of results on both Day 1 and Day 5 showed no significant differences among any of the three PEG-rHuMGDF doses and the control group, for any in vitro assay. One-dimensional polyacrylamide gel electrophoresis showed no changes among the platelet protein patterns for the three PEG-rHuMGDF doses studied or the control. Storage-induced changes, however, did occur equally in all four groups of platelets over the 5 days of storage.

CONCLUSION

The addition to stored apheresis platelets of up to 10 microg per kg of PEG-rHuMGDF (250 ng/mL), followed by 5 days of storage at standard conditions, does not appear to promote or retard development of the platelet storage lesion.

Effects of methylene blue-treated plasma on red cells and stored platelet concentrates

BACKGROUND

Photochemical methods can effectively inactivate extracellular viruses and bacteria found in blood components. Treatment of plasma with methylene blue (MB), a phenothiazine dye, and visible light inactivates enveloped viruses including HIV-1. The effects of MB-treated plasma on cellular components stored in vitro have not been well characterized.

STUDY DESIGN AND METHODS

MB-treated plasma (83 microg MB/250 mL plasma) was added to single-donor platelets, stored AS-1 red cells (RBCs), irradiated RBCs, and frozen-deglycerolized RBCs. In vitro platelet assays performed after 1 and 5 days of storage in MB-treated plasma included pH, pO2, pCO2, HCO3, platelet number, lactate dehydrogenase, glucose, osmotic recovery, and CD62 expression. RBC components were examined at specific intervals for leakage of potassium, plasma hemoglobin level, and percentage of hemolysis. Direct antiglobulin tests, osmotic fragilities, and RBC antigen stability tests were also performed on RBCs stored in MB-treated plasma. Components stored with autologous plasma or nontreated allogeneic plasma served as controls.

RESULTS

Similar storage-induced changes in pH, glucose, and platelet numbers, as well as increases in lactate dehydrogenase, CD62 expression, and lactate were seen in single-donor platelets stored with MB-treated and control plasma. Platelet morphology scores and osmotic recoveries were not altered. Plasma hemoglobin and potassium and percentage of hemolysis increased equally in the various RBC components stored with MB-treated or nontreated plasma. Osmotic fragility and RBC antigen stability were not appreciably altered by MB-treated plasma.

CONCLUSION

Plasma treated by MB photoinactivation can be used for in vitro resuspension and storage of platelets or RBCs, because of the lack of influence of MB-treated plasma on a variety of in vitro platelet and RBC assays.

Transfusion of platelet concentrates--clinical evaluation of two preparations

The aim of this study was to compare the clinical effect of transfusion of platelet concentrates (PC) prepared from pooled buffy coats (BC) and PCs collected from a single donor (SD) by an apheresis technique. The influence of storage time and various clinical conditions was also studied. Thirty-two patients suffering from haematological malignancies were given a total of 326 platelet concentrates; 180 BC-PCs and 146 SD-PCs, median 7 transfusions per patient. BC-PCs contained 312 +/- 52 x 10(9) and SD-PCs 383 +/- 133 x 10(9) platelets/unit (mean +/- SD). The mean storage time of BC-PC was 3 d and that of SD-PC 1 d. The mean platelet count of the patients before transfusion was 11 +/- 8 x 10(9)/L. Regression analysis showed a significant decrease of the post-transfusion platelet corrected count increment (CCI) during storage of PCs for 1-5 d (BC-PC: p < 0.01; SD-PC: p < 0.05). There was no difference in platelet increment between BC-PC and SD-PC. Human leukocyte antigen (HLA) alloimmunization was the major cause of clinical refractoriness to random donor platelet transfusions but splenomegaly also caused low CCI values.

In vitro platelet ageing at 22 degrees C is reduced compared to in vivo ageing at 37 degrees C

In these studies, platelet ageing during in vitro at 22 degrees C was compared with in vivo ageing using isotope labelling. Paired fresh and 5-d-stored platelets had a mean residual life-span (MRL) of 4.8 +/- 0.7 d and 3.2 +/- 0.9 d, respectively. After 2.1 +/- 0.4 d in vivo circulation, the MRL of the fresh platelets was equivalent to that of the 5-d-stored in vitro platelets. This suggests that platelet ageing for 5 d in vitro at 22 degrees C corresponds to 2.1 d in vivo ageing at 37 degrees C. Thus, the relative ageing at 22 degrees C in vitro was (2.1 d/5 d) = 0.42 of that at 37 degrees C in vivo. A similar ageing ratio (0.44) was obtained by measurement of the decrease in MRL during storage at 22 degrees C of platelets stored for 1, 5, 7, 10 and 14 d relative to the decrease in MRL of fresh platelets in vivo. ATP turnover rate at 22 degrees C was compared to the rate of 37 degrees C by measurement of the rates of platelet oxygen consumption and lactate production in vitro. In vitro ATP turnover at 22 degrees C versus 37 degrees C, was found to be 10.5 +/- 1.0 versus 21.6 +/- 1.4 mumol/10(12) plts/min, respectively. Thus, the ATP turnover ratio (0.48) at these two temperatures suggests that the relative decrease in ageing at 22 degrees C compared to 37 degrees C is similar to the relative decrease in metabolic rate at this temperature.

Buffy-coat-derived platelet concentrates prepared from half-strength citrate CPD and CPD whole-blood units. Comparison between three additive solutions: in vitro studies

The in vitro effects of storage of platelets prepared from 4 or 6 pooled buffy coat (BC) units and stored in a platelet storage medium consisting of 30-40% of CPD plasma or alternatively half-strength citrate CPD (0.5 CPD) plasma and 60-70% of different alternative platelet additive solutions (PASs) were evaluated. Measurements of mean platelet volume, pH, pO2, pCO2, bicarbonate, glucose, lactate, ATP, total adenine nucleotide content, extracellular lactate dehydrogenase or adenylate kinase activity, as markers for disintegration of platelets, and extracellular beta-thromboglobulin, as a marker for activation of platelets, were included in the in vitro studies. Previous studies indicated that a reduction of the citrate concentration from the standard 21 to 8 mmol/l is associated with a significant reduction of the consumption of glucose and production of lactate. Alternatively, similar effects can be obtained by the addition of acetate. In a preliminary paired study, the effects of different concentrations of acetate were tested. In an additional paired study, the effects of CPD plasma in combination with either saline or a PAS containing NaCl (115.5 mmol/l), citrate (10 mmol/l), and acetate (30 mmol/l), pH 7.2 (PAS-2) were evaluated. 0.5CPD plasma in combination with either PAS-2 or a nonacetate PAS (PAS-1) were also tested. The storage of platelets in 0.5CPD plasma was used as a reference. The conclusions are: (1) A minimum acetate concentration of 30 mmol/l is needed to counteract the effects of citrate on the production of lactate. (2) pH and the bicarbonate buffering capacity are significantly better maintained in PAS-2 than in PAS-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of agitation on the quality of platelet concentrates

Platelet concentrates (PCs) were stored for 4 days at 22 degrees C in 400 ml second-generation (PL1240) platelet packs with either constant agitation, manual mixing once every 24 h or without agitation at any time. After 4 days storage, in vivo recovery, survival and biodistribution were determined following indium-111 labelling of platelets and infusion into autologous volunteers. In vitro assays of platelet function and biochemistry were likewise carried out after 4 days storage. The PCs stored without agitation had significantly lower in vivo recoveries, pH and aggregation responses to ionophore A23187 and a combination of collagen and epinephrine and significantly higher beta-thromboglobulin and indium-111 release than the agitated PCs. The manually mixed PCs were not significantly different from the constantly agitated PCs. PCs mixed simply once every 24 h remained viable with active oxidative phosphorylation and a pH above 6.74 in all but 1 case indicating that PCs stored at 22 degrees C for up to 4 days with only intermittent mixing are satisfactory for transfusion. A change from constant agitation would reduce capital costs in mixing equipment and simplify the transport of PCs from the transfusion centre to small hospital blood banks.

Concurrent label method with 111In and 51Cr allows accurate evaluation of platelet viability of stored platelet concentrates

The precision and reproducibility of 111In and 51Cr platelet radiolabel agents for in vivo kinetic studies of stored platelet concentrates (PC) were investigated. The objective was to develop a precise method with concurrent labelling of two platelet populations using different isotopes, which would allow identification of small differences in in vivo platelet quality. Identical labelling procedures were used to investigate the effects of PC storage age, different methods of red cell (RBC) and white cell (WBC) contamination correction, and label elution correction on the results of 111In and 51Cr kinetic studies. 111In and 51Cr platelet survival curves from the same PC, even when uncorrected for elution and RBC contamination, exhibited excellent correlation, irrespective of the age of the concentrate and its viability. However, slightly higher, but statistically significant, post-infusion per cent recoveries with 51Cr labelled platelets were found. Two factors were identified as the cause for this difference. There was a higher affinity of contaminating RBC/WBC in PC for 51Cr than for 111In. With determination of RBC/WBC activity by centrifugation/density separation, RBC/WBC fractions from the injectate were found to contain 12.6 +/- 3.8% v 7.1 +/- 3.6% of total 51Cr and 111In activity, respectively, in 20 studies. In addition, there was a significantly higher 111In activity in plasma immediately post-infusion than with 51Cr, 5.2 +/- 1.3% v 2.8 +/- 1.6%, respectively, suggesting more label elution or carryover. After correction for the activity of RBC/WBC and for elution or carryover, essentially identical 51Cr/111In platelet survival curves were found. In 31 stored PC studies, the absolute average difference between 51Cr and 111In per cent recoveries was only 4 +/- 3% in a group of donors whose platelet recoveries ranged from 10% to 80%. Similarly, the average difference between 51Cr and 111In survival was only 8 +/- 4 h within a range of survivals from 40 to 220 h. In conclusion, after correction for elution and contaminating RBC/WBC binding, these studies show that 51Cr and 111In may be used interchangeably for labelling of stored PC, and that small differences between test and control platelets could be reliably detected using concurrent labelling with simultaneous infusion.

Five-day storage of platelets in a non-diethylhexyl phthalate-plasticized container

A non-diethylhexyl phthalate (DEHP)-plasticized blood bag for 5-day storage of random-donor platelet concentrates has been developed. The plastic bag is composed of polyvinylchloride plastic with a butyryl trihexyl citrate plasticizer. The suitability of this plastic for the storage of platelet concentrates for use in clinical transfusion practice was evaluated. In vitro storage studies showed no significant differences at Day 5 for a series of in vitro assays (test plastic vs. control plastic) including pH (7.31 vs. 7.44), lactate dehydrogenase discharge (21.8 vs. 17.1%), pO2 (103 vs. 120 torr), osmotic recovery (52 vs. 57%), and morphology score (527 vs. 516). For paired radiolabeled recovery and survival data from autologous blood donors, results showed equivalence between the test plastic and two control plastics. A small but significant difference between test and control plastics in regard to survival was found by using a linear computer model, but not with a gamma function (multiple-hit) model. For paired transfusions to thrombocytopenic patients, the corrected count increments at 1 to 4 hours (test vs. control) were 13,534 versus 15,494 (p > 0.05, NS). Similar results were seen for corrected count increments determined at 12 to 24 hours. It can be concluded that platelets stored in the test plastic are acceptable for use in clinical practice.

Pretransfusion incubation of apheresis platelets at 37 degrees C improves posttransfusion recovery

The effect of brief 37 degrees C pretransfusion incubation of apheresis platelets (n = 25) was studied in 14 allogenic bone marrow transplant recipients (5 children, 9 adults). Apheresis platelets were collected on a cell separator, divided in two aliquots, and stored 1 to 5 days at 22 degrees C during agitation. One aliquot was incubated at 37 degrees C for 1 hour before transfusion, and the other was transfused as a paired control. When the patient's peripheral platelet count fell below 30 x 10(9) per L, one aliquot was transfused. The other aliquot was transfused the following day. Each patient received the two aliquots in random order. Corrected count increment (CCI) at 1 hour after transfusion of 37 degrees C incubated platelets was 12.2 +/- 9.5 (mean +/- SD) compared to 7.5 +/- 5.4 for paired control platelets (p < 0.05). CCIs the next day were 4.4 +/- 6.1 and 2.4 +/- 2.7, respectively (not significant). It can be concluded that 37 degrees C incubation of apheresis platelets improves posttransfusion CCI.

Post-transfusion recovery of function of 5-day stored platelet concentrates

Platelets show a rapid reduction in their responsiveness to aggregating agents during storage for transfusion, but little is known about reversal of this defect in vivo after transfusion. In this study, fresh and stored platelets from the same donor (n = 12) were labelled with 111In or 51Cr, respectively, mixed, and simultaneously infused. Blood samples were taken for up to 5 d post-infusion, and the functional behaviour of the labelled platelets ex vivo was measured by retention on glass bead columns, and by whole blood aggregability to ADP, epinephrine and ristocetin. Aggregation was determined by filtering aggregated samples through a column of cotton wool to remove the aggregates, and quantitated as per cent decrease in radioactive counts. The study showed that, although infused radiolabelled 5 d stored platelets had a significantly lower aggregability towards ADP and epinephrine immediately (1 h) after infusion (32% and 29%, respectively, of fresh platelet values), a complete restoration to fresh platelet levels was found 24-72 h post-infusion, with no further change observed over the ensuing 5 d with either fresh or stored labelled platelets. A slightly (6-9%) lower adhesion to both uncoated and collagen-coated beads was found for the stored platelets throughout the 5 d period of study post-infusion. In conclusion, these studies show that, with ex vivo testing, platelets stored for 5 d quickly recovered adhesion and aggregability capabilities similar to that of fresh platelets, suggesting that the functional lesion developed during storage is quickly and completely reversed after infusion.

Storage of platelets in a new plastic container. Polyvinyl chloride plasticized with butyryl-n-trihexyl citrate

The effect of storage of platelets in a new polyvinyl chloride (PVC) plastic material with a butyryl-n-trihexyl citrate (BTHC) plasticizer (PL 2209) was evaluated. The PL 1240 container, i.e. PVC plastic with a different plasticizer, tri-(ethylhexyl)-tri-mellitate, was used as a reference. Measurements of pH, pO2, pCO2, glucose, lactate, adenosine triphosphate, total adenine nucleotide content, lactate dehydrogenase and platelet factor 4 (PF4) were made during 5 days of storage. Similar results were noted comparing PL 2209 and PL 1240. Differences in pO2 and pCO2 indicate greater gas permeability in PL 2209 than in PL 1240. Significantly higher PF4 levels were found in PL 2209, but the difference could not be attributed to the PL 2209 container itself. Paired autologous reinfusion studies (111Indium) of 6 normal donors gave mean recovery values after 5-day storage of 41.1 +/- 7.4% (PL 2209) and 45.5 +/- 7.7% (PL 1240), t1/2 66 +/- 13 and 75 +/- 5 h, survival time (linear model) 6.3 +/- 1.0 and 6.8 +/- 0.7 and survival time (multiple-hit model) 6.0 +/- 0.7 and 6.5 +/- 0.4 days, respectively. Only the difference in survival time (multiple-hit) was significantly higher in PL 1240. The corrected count increments at 12-24 h following transfusion were 13,300 +/- 10,800 (PL 2209) and 13,600 +/- 11,600 (PL 1240) with no statistically significant difference found. These results indicate PL 2209 as an equivalent alternative to PL 1240 for the 5-day storage of platelets.

The in vivo kinetics of 111In- and 51Cr-labelled platelets: a comparative study using both stored and fresh platelets

The in vivo kinetics of simultaneously injected 51Cr- and 111In-labelled platelets was investigated in 20 healthy male volunteers. The studies were carried out using both fresh platelets and platelets stored for 5 d at 22 degrees C; the disappearance of platelet-bound radioactivity was measured on whole blood samples as well as platelet pellets. Compared to 111In, the labelling efficiency was notably lower for 51Cr, and a higher amount of 51Cr was bound to contaminating red cells. As regards the fresh platelets, only small dissimilarities were observed in the in vivo kinetics obtained with the two labels. 51Cr yielded a slightly higher platelet recovery and longer T1/2 than 111In, when whole blood samples were used for calculations; no differences were seen when using platelet pellets. When stored platelets were studied, 51Cr gave significantly longer T1/2 and mean life-span (MLS) than did 111In. This difference was present for all mathematical models used for the calculation of MLS, and when whole blood samples as well as platelet pellets were employed. It was demonstrated that the estimation of MLS was also highly dependent upon techniques of blood sampling and curve fitting. Calculation, in which the initial data points were excluded, gave consistently longer MLS (P less than 0.0001), as compared to when all data points were included. Furthermore, when all survival studies were grouped together, calculations using platelet pellets gave a significantly (P less than 0.001) shorter platelet MLS than calculations using whole blood samples. It is concluded that both 51Cr and 111In are acceptable as radiolabels for both fresh and stored platelets. However, it appears that the viability of stored platelets may be influenced by the choice of label, and caution must be taken when these isotopes are used together in dual tracer experiments. Also, our results show that a meticulously standardized processing of blood samples and experimental data is required to enable interlaboratory comparisons of the results.

Platelet membrane glycoproteins and platelet functions during storage in the presence of a proteinase inhibitor

The effect of the proteinase inhibitor aprotinin on membrane glycoproteins and functions of platelets stored for 5 days in platelet-rich plasma was tested. Platelet membrane glycoprotein content was determined by flow cytometry or immunoblot techniques using different monoclonal antibodies. ADP- and ristocetin-induced platelet aggregation and adhesion to collagen were tested in parallel. Using the flow-cytometry technique i) a progressive decrease in the percentage of platelets reacting with the different monoclonal antibodies was observed during storage ii) a 30% reduction of the GPIb mean fluorescence intensity (MFI) was observed after 5 days storage while the MFI of the GP IIb-IIIa complex was not modified. Using the immunoblot technique, a decrease in the amount of both the GPIb alpha and the component of Mr 100,000 was observed, while a 50,000 Mr fragment appeared progressively. Platelet adhesion and aggregation were reduced after 24 hours of storage. Aprotinin prevented neither the GPIb alpha reduction nor the modifications of the functions of human platelets stored in their autologous plasma.

Clinical evaluation of the effects of storage time and irradiation on transfused platelets

Platelet concentrates stored for up to 5 days at room temperature or irradiated with 15 Gy immediately prior to transfusion were evaluated for their ability to increase the platelet count in thrombocytopenic patients. Platelets irradiated with a dose of 15 Gy immediately prior to transfusion achieved corrected increments (CI) at 1 and 20 h after transfusion no different from those achieved by non-irradiated platelets. Storage for 5 days reduced the mean 1-hour CI to 5.7 compared with a mean of 12.3 achieved by platelets transfused after only 1-day storage (p = 0.008). Similarly, the frequency of a repeat transfusion being indicated within 24 h increased with increasing storage time (p = 0.005).

Storage of platelets in earth orbit. Effect of gravity and the formulation of plastic storage containers on platelet IgG and C3

We investigated the effects of gravitational force and three different plastic formulations of the storage bags on the quality of stored platelets by measuring the changes in platelet-associated immunoglobulin G (IgG) and two antigenic markers of the third component of human complement (C3), C3d and C3c. Pooled platelets were stored in parallel at microgravity (MG) and on the ground (1 g) using three different plastic polymers: (1) polyvinylchloride (PVC) plasticized with di-2-ethylhexyl phthalate (DEHP); (2) PVC plasticized with trioctyl trimellitate (TOTM), and (3) unplasticized polyolefin (PO). The IgG and C3 were quantified by an automated antiglobulin consumption test in freeze/thaw disrupted platelets (total IgG or C3). The baseline values for platelet associated IgG and C3, measured after 2.5 days of storage at 1 g just prior to the launch, fell within the normal range. Following an additional 6.5 day storage, platelets stored at MG had accumulated significantly less C3d than those stored at 1 g, suggesting that MG storage was beneficial. Specific plastic formulations also exerted a significant effect on the accumulation of these immunoproteins, the effect being particularly pronounced at MG. The smallest increases of IgG and C3 were seen in platelets stored in TOTM and the largest in those stored in DEHP. It is possible that further studies at MG would permit a clear characterization of the effects of other independent storage variables.

A novel second-generation polyolefin container for storage of single-donor apheresis platelets

A non-blow-molded LE-2 polyolefin (PO) container was developed to store single-donor apheresis platelet concentrates (PCs) processed by the Haemonetics Plasma Collecting System (PCS) at 22 degrees C for over 1 day. We molded PO containers with heat-sealing of light-weight polymer alloy films with a thickness of 0.25 mm. The film was made of polymer blends consisting of polypropylene, styrene ethylene butylene styrene-block copolymer, and ethylene ethylacrylate copolymer. The PO container with enough strength and flexibility in routine practice has 2 and 1.6 times higher oxygen and carbon dioxide gas transfer properties than standard polyvinyl chloride (PVC) plastic containers. PCs (1-1.9 x 10(11) platelets) processed from 450 ml platelet-rich plasma were stored in 0.6-liter PO containers at 22 degrees C with flatbed agitation for up to 6 days. The pH of PCs was well maintained at the mean values of 7.0 in PO containers after 6 days in the well-oxygenated condition. The energy metabolism of stored platelets was determined. Oxygen consumption rates of platelets stored in PO containers averaged 1.5 nmol/min/10(9) platelets. The rates of glucose consumption and lactate production were 0.4 and 0.8 nmol/min/10(11) platelets, respectively. The rates of adenosine triphosphate (ATP) generation of platelets, 9.7 nmol/min/10(9) platelets, in PO containers did not differ from those in the PVC containers. Aggregation responses to adenosine diphosphate and hypotonic shock response of platelets were better maintained in PO containers. The morphological changes into sphere forms with projections and the appearance of unclassified forms were more frequently observed in PO than in PVC containers.(ABSTRACT TRUNCATED AT 250 WORDS)

[In vitro study of platelet preservation during 5 days in reduced-thickness bags]

An in vitro study of platelet concentrates storage for 5 days was performed in PVC bags. Modification of the original three-day containers were introduced by thickness reduction. The results at fifth day were comparable to those at third day in standard plastic bags. During storage, variations of platelet counts were very slight with a low LDH release. PH was stable with a good maintenance of phase microscope platelet morphology. PCO2 and PO2 measurements showed a satisfactory gas permeability which could explain a limited lactate production. If in vivo studies of transfusion recovery confirm these data, platelet concentrates storage could be extended up to 5 days by such modifications of standard three-day PVC bags.

Peroxidative events in stored platelet concentrates

Changes in metabolic and functional activity of platelets stored as platelet concentrates in plastic bags highly permeable to gases were investigated. The following parameters were measured daily: pH, pO2, pCO2, HCO3, glucose, lactic acid, lactic dehydrogenase, cellular ATP and platelet aggregation induced by different agents (collagen and ADP). As indexes of lipid peroxidative damage, the cellular levels of conjugated dienes, malonyldialdehyde and some antioxidant molecules such as coenzyme Q10 and vitamin E were determined. A marked increase in pO2, conjugated dienes, malonyldialdehyde, lactic acid and lactic dehydrogenase activity was observed during the preservation. Platelet ATP content was unmodified and a remarkable decrease in platelet aggregability was found. pCO2, cyclooxygenase activity, vitamin E, coenzyme Q10, bicarbonate and glucose showed a rapid fall. Our data seem to indicate a preservation of platelet metabolic activity and a correlation between increased lipid peroxidation and functional impairement.

Centrifugation of very freshly donated blood may yield platelets unstable to storage in the new generation of containers

The stability of platelets stored in the second generation of container has been examined further. Platelet concentrates prepared in CPD anticoagulant were found to deteriorate fairly rapidly during storage if prepared from very freshly donated blood, whereas a more than 4-hour delay between donation and platelet isolation yielded platelet concentrates much more stable to storage. Delays of more than 2 h (relative to the time of donation) in the isolation of platelets led to decreases in the aggregation response to low or moderate doses of collagen. Platelets from blood collected into CPD adenine showed decreased aggregation responses relative to equivalent cells from blood collected into adenine-free anticoagulant. It seems that a decreased aggregation response is associated with improved storage properties.

Loss of low-affinity serotonin receptors upon storage of human platelets

Platelets actively accumulate virtually all plasma serotonin within their dense granules. As a readily isolated, homogeneous cell type, platelets have served as a model for serotonin uptake into neurological tissue, in addition to defining the role of serotonin in hemostasis. The number of serotonin receptor types on the platelet membrane and the function of these receptors has not been conclusively demonstrated. The presence of different receptor types that may be altered or lost in disease or upon aging (in vitro storage or in vivo) could have significant physiological effects on platelet function. This report demonstrates that at least two receptor types are present on freshly prepared human platelets. However, after 3 to 4 days of storage in autologous plasma, the low-affinity, high-capacity serotonin receptor appears to be lost. This phenomenon probably accounts for some of the discrepancies reported in the literature. The high-affinity receptor present in both freshly isolated and stored platelets binds about 9 x 10(3) serotonin molecules per platelet. Binding can be completely blocked by imipramine; however, some passive diffusion appears to occur even at the low level of extracellular serotonin concentrations employed in these studies (nanomolar range). The influx of serotonin into platelets appears to be poorly reversible, even in reserpine-treated cells, where the extravesicular cytoplasmic concentration would be high. The loss of the low-affinity serotonin receptor type reported in these studies may be directly or indirectly associated with the reduced responsiveness observed in stored platelets.

Preparation of leucocyte-poor platelet concentrates from buffy coats. IV. Clinical evaluation

To study survival and function of leukocyte-poor platelet concentrates (lp-PC) prepared from buffy coats, random platelet transfusions requested for thrombocytopenic patients were evaluated. The lp-PC issued were stored at 22 degrees C for either 1, 3 or 5 days before transfusion. From 31 transfusions, posttransfusion corrected count increments (CCI), corrected for body surface (m2) and divided by number of platelets transfused (1011), were calculated. The mean +/- SEM of the 1-, 24- and 48- hour CCI was 12.2 +/- 0.45, 11.2 +/- 0.51 and 8.8 +/- 0.58, respectively. No significant differences in CCI 24 h after transfusion were observed for 1p-PC stored for 1, 3 or 5 days. Hemostatic activity was observed in all 9 evaluable patients. It is concluded that platelets from 1p-PC survive well in patients, regardless of storage for 1, 3 or 5 days and that the platelets are hemostatically active after transfusion.

Studies on the procurement of blood coagulation factor VIII. In vivo studies on blood components prepared in half-strength citrate anticoagulant

To determine the viability of blood cells collected in half-strength (0.5 CPD.A2) and full-strength citrate anticoagulants, paired crossover autologous survival studies were performed in normal volunteers using 51Cr-labelled red cells after 35 days storage and 111In-labelled platelets after 5 days storage. For both studies, viability was better maintained in 0.5 CPD.A2 anticoagulant. This was significant for red cells (24-hour survival: 80 +/- 6 vs. 52 +/- 21%) but not for platelets by either linear or multiple-hit models (recovery 51 +/- 13 vs. 38 +/- 14%, survival 5.1 +/- 1.4 vs. 3.7 +/- 1.5 days). The poor viability of red cells after storage in full-strength anticoagulant was associated with low cellular adenosine triphosphate levels and was confirmed in follow-up studies.

Platelet storage lesion in second-generation containers: correlation with platelet ATP levels

The nature of platelet lesion occurring with storage of platelet concentrates (PC) in second-generation containers was investigated using various storage media and storage periods up to 14 days. In CPD-plasma (control medium), the changes which occurred progressively during storage were loss of discoid shape, microscopic platelet aggregate formation, fragmentation and the appearance of disintegrated, 'balloon' forms. By day 14 less than 10% of the platelets were discoid in shape, the platelet count had decreased by 23%, and there was a 5-fold increase in the amount of lactate dehydrogenase in plasma. Associated with this was a decrease in the platelet oxygen consumption rate, D(O2), loss of cellular ATP and extent of ADP-induced shape change, and a decrease in the hypotonic shock response. These parameters decreased at a similar rate, with a 50% decrease (t1/2) at days 7-9. They correlated highly with each other during storage and also with a fall in pH. At day 14 of storage, mean pH was 6.1 +/- 0.3. To evaluate the effect of pH stabilization during storage, 4 mEq sodium bicarbonate was added to PC in CPD-plasma. Although pH maintenance was much improved, 7.2-6.6 during 14 days of storage, the same in vitro lesions developed, although more slowly. The t1/2 of the same parameters was prolonged for approximately two days. When PC were stored in a plasma-free physiologic salt solution whose salt composition was similar to CPD-plasma, the t1/2 of the parameters increased to 11-15 days of storage, although the platelets eventually developed the same in vitro lesions.(ABSTRACT TRUNCATED AT 250 WORDS)