Extension of platelet concentrate storage

Platelet in vitro assays: their correspondence with their in vivo hemostatic potential

Developments during the past few years have resulted in multiple kinds of platelet products for transfusion. This involves different collection methods, containers, preservative solutions, modifications of storage temperatures and durations, and additional treatments such as pathogen reduction. Much experience has been obtained testing these processes in vitro to seek indications of in vivo effectiveness. Availability of an in vitro method that correlated with in vivo effectiveness would be extremely valuable for these different kinds of platelet products and as more innovation in platelet preparation occurs in the future. This report reviews the methods for in vitro platelet testing with a view to their in vivo implications and whether such testing could be helpful in projecting the clinical effectiveness of different platelet products.

Automated cold temperature cycling improves in vitro platelet properties and in vivo recovery in a mouse model compared to continuous cold storage

BACKGROUND

Platelets (PLTs) stored at cold temperatures (CTs) for prolonged time have dramatically reduced bacterial growth but poor survival when infused. A previous study demonstrated that human PLTs stored with manual cycling between 4 °C (12 hr) and 37 °C (30 min) and infused into severe combined immunodeficient (SCID) mice had survivals similar to or greater than those stored at room temperature (RT). In this study, the in vitro and in vivo properties of PLTs stored in an automated incubator programmed to cycle between 5 °C (11 hr) and 37 °C (1 hr) were evaluated.

STUDY DESIGN AND METHODS

A Trima apheresis unit (n = 12) was aliquoted (60 mL) in CLX bags. One sample was stored with continuous agitation (RT), a second sample was stored at 4-6 °C without agitation (CT), and a third sample was placed in an automated temperature cycler with 5 minutes of agitation during the warm-up period (thermocycling [TC]). PLTs were assayed for several relevant quality variables. On Day 7, PLTs were infused into SCID mice and in vivo recovery was assessed at predetermined time points after transfusion.

RESULTS

The glucose consumption rate, morphology score, hypotonic shock recovery level, and aggregation levels were increased and mitochondrial reactive oxygen species accumulations were decreased in TC-PLTs compared to those of CT-PLTs. The pH and Annexin V binding were comparable to those of RT-PLTs. All TC-PLTs had greater recovery than CT-PLTs and were comparable to RT-PLTs.

CONCLUSION

PLTs stored under automated TC conditions have improved in vivo recovery and improved results for a number of in vitro measures compared to CT-PLTs.

Addition of sialidase or p38 MAPK inhibitors does not ameliorate decrements in platelet in vitro storage properties caused by 4 °C storage

BACKGROUND AND OBJECTIVES

Bacterial proliferation is inhibited in platelets (PLTs) stored at refrigerated temperatures, but also dramatically decreases PLT in vivo survival. Recent studies have demonstrated that cold temperature (CT) stored PLTs secrete sialidases upon re-warming, removing sialic acid from the PLT surface, which may be responsible for clustering of GPIbα and PLT clearance from circulation. In this study, the influence of a sialidase inhibitor or a p38 MAP kinase inhibitor was evaluated in units stored at 4 °C.

MATERIALS AND METHODS

After collection of a single Trima apheresis unit (n = 12), PLTs were aliquoted into four 60-ml CLX storage bags. One bag was stored at 20-24 °C (RT) with continuous agitation; a second bag was stored at 4 °C without agitation; a third bag was held at 4 °C without agitation with sialidase inhibitor, a fourth bag was incubated at 4 °C with a p38 MAPK inhibitor without agitation.

RESULTS

Beginning from Day 1, all in vitro PLT parameters were adversely affected by CT compared to those of RT. Similar in vitro storage properties were observed in CT PLT in the presence or absence of sialidase or p38 MAPK inhibitors. P38 MAPK phosphorylation inhibition was not observed at CT. Decrease of sialidase activity was observed for 2 days in PLTs stored in additive solution but not in plasma.

CONCLUSION

Addition of either sialidase or p38 MAPK inhibitors do not improve any in vitro parameters of PLTs stored at 4 °C in 100% plasma.

Current status of additive solutions for platelets

The storage of platelets in additive solution (PAS) had lagged behind red cell concentrates, especially in North America. The partial or complete removal of anticoagulated plasma and storage of platelet concentrates in AS presents many advantages. The PAS can be formulated to optimize aerobic metabolism or decrease platelet activation, thus abrogating the platelet storage lesion and potentially improving in vivo viability. Plasma removal has been shown to reduce allergic reactions and the plasma harvested could contribute to the available plasma pool for transfusion or fractionation. PAS coupled to pathogen reduction technology results in a platelet product of equivalent hemostatic efficacy to conventionally stored platelets. Given the above, the likely future direction of platelet storage will be in new generation designer PAS with an extended shelf life and a superior safety profile to plasma stored platelets. J. Clin. Apheresis, 2012. © 2012 Wiley Periodicals, Inc.

Preparation, storage and quality control of platelet concentrates

Patients with thrombocytopaenia need transfusions of platelet concentrates to prevent or stop bleeding. A platelet transfusion should provide platelets with good functionality. The quality of platelet concentrates (PCs) is affected by the preparation method and the storage conditions including duration of storage, type of storage container, and storage solution (plasma or an additive solution). Different in vivo and in vitro techniques can be used to analyse PCs. Platelets can be collected by apheresis technique, and from whole blood using either the buffy-coat or the platelet-rich plasma method. PCs can be gamma irradiated to prevent occurrence of graft-versus-host disease in the recipient. Pathogen inactivation procedures have been developed to prevent transmission of bacteraemia.

Platelet storage lesion: a new understanding from a proteomic perspective

Platelet storage and availability for the purposes of transfusion are currently restricted by a markedly short shelf life of 5 to 7 days owing to an increased risk of bacterial growth and storage-related deterioration called the platelet storage lesion. Because most bacteria grow to confluence within 5 days during storage at room temperature, there is little increased risk of bacterial overgrowth with testing in place, and the only remaining issue is the quality of platelets during the extended storage. Although the manifestations of the storage lesion have been well studied using a variety of in vitro measures, the precise biochemical pathways involved in the initiation and progression of this process have yet to be identified. Proteomics has emerged as a powerful tool to identify and monitor changes during platelet storage and, in combination with biochemical and physiologic studies, facilitates the development of a sophisticated mechanistic view. In this review, we summarize recent experimental work that has led to a detailed overview of protein changes linked to platelet functions and signaling pathways, providing potential targets for inhibitors to ameliorate the storage lesion.

The introduction of 7-day platelets: a university hospital experience

INTRODUCTION

Recently, the FDA approved the Post Approval Surveillance Study of Platelet Outcomes, Release Tested protocol which allows participating institutions to utilize 7 day platelets following guidelines. As one of the first hospitals to implement a 7-day protocol, we reviewed our hospital experience with 7-day Gambro apheresis platelets to determine the impact on inventory.

METHODS

A review of apheresis platelet transfusions and outdate records was performed. Data were collected prospectively from March to August 2006. This data were compared with a retrospective review for the same time period in 2005.

RESULTS

For the 1,503 platelets transfused from March-August 2005, the mean day of issue was 3.44 (SD = 1.060). During the same time period of 2006, 1,688 platelets were transfused with a mean day of issue of 4.02 (SD = 1.083). This difference was statistically significant (P < 0.001). The outdate rate dropped from 2.9% (44/1,547) to 1.3% (22/1,710, P < 0.001). During the study period, approximately 59.7% of the platelets were 7-day platelets.

DISCUSSION

Over the 6-month period, we noted a decrease in outdates from 2.9% to 1.3%. There was a shift toward older platelets (from a mean of day 3.4 to day 4). During the study period, 139 platelets were transfused on days 6 or 7 of storage. Overall, the implementation of 7-day platelets in a university hospital setting was easily accomplished and has resulted in benefits to our institution by decreasing our outdate rate and to our patients by providing an additional 139 days 6 and 7 apheresis platelets with a potential cost savings of $78,952 (over the 6-month study).

In vitro and in vivo evaluation of leukoreduced platelets stored for 7 days in CLX containers

BACKGROUND

Extension of platelet (PLT) storage and concomitant use of a bacterial detection system would provide logistical advantages by reducing outdating and improving patient care through promotion of the use of sensitive detection systems. This study evaluated the in vitro characteristics and in vivo viability of leukoreduced PLT units derived from PLT-rich plasma stored for 5 days (control) versus 7 days (test) in CLX plastic containers.

STUDY DESIGN AND METHODS

Two whole-blood units were collected from each subject into a leuko-reduction filtration system (Leukotrap RC-PL system, Pall Medical) in a paired design, the second 2 days after the first. These were leukoreduced (Leukotrap PL) and stored for 7 and 5 days. Poststorage samples from test and control units were randomly labeled with (51)Cr or (111)In and simultaneously infused autologously to determine recovery and survival.

RESULTS

Small but significant (p < 0.05, paired t test) differences between 5 and 7 days of storage were seen in in vitro variables such as extent of shape change, hypotonic shock response, morphology, and P-selectin expression. In vivo recovery declined on average 11 percent with the two additional days of storage from 54.4 +/- 13.6 to 48.7 +/- 15.0 percent (p < 0.002); survival decreased on average 19 percent from 6.7 +/- 1.0 to 5.4 +/- 1.7 days (p < 0.002).

CONCLUSION

Storage for 7 days was associated with reduced recovery and survival and in vitro variables, suggestive of extension of the storage lesion. These differences, however, were small in magnitude and unlikely to have significant clinical effects. Current collection and storage systems provide PLTs that are as functional at 7 days as those licensed for 7-day storage two decades ago.

Detection of bacterial contamination of platelet components: six years’ experience with the BacT/ALERT system

BACKGROUND

Hemovigilance has shown that bacteria cause more fatalities than other infections together. Surveillance for detection of bacteria in platelets (PLTs) was initiated. Concomitantly, the storage period for PLTs was extended from 5 to 7 days to reduce cost.

STUDY DESIGN AND METHODS

Analysis was performed of all cases of a positive signal in a screening procedure for contaminated PLTs taking into account results of confirmative cultures and results of culture from blood components including bacteria strains. Records were assessed from patients transfused with blood components issued before the screening culture became positive.

RESULTS

Samples were collected from 22,057 PLT units. An initial reaction was seen in 84 (0.38%). Growth was confirmed in 70 of these. Of the associated PLT units, 26 had been issued or outdated at the time when the culture was found to be reactive, in 27 bacteria were found, and in 17 cultures were negative. The bacteria found were mainly from normal skin flora. Sixty-six patients received 75 blood components issued before the screening system alarmed. None of these patients had a transfusion reaction reported. The outdating fell to less than 5 percent.

CONCLUSION

A screening system for detection of bacterial contamination was implemented without increase in cost owing to extension of storage time to 7 days. Transfusion of several contaminated blood components was prevented.

In vivo PLT increments after transfusions of WBC-reduced PLT concentrates stored for up to 7 days

BACKGROUND

Bacterial screening and improvement of storage conditions of leukoreduced PLT concentrates (LR-PCs) allows extension of their storage period from 5 to 7 days.

STUDY DESIGN AND METHODS

For in vitro studies, 40 LR-PCs made from five buffy coats and plasma were studied for 8 days. For in vivo studies, routinely produced LR-PCs stored for 2 to 7 days after blood collection were administered to clinically stable thrombocytopenic patients. CI1 h was calculated after 353 transfusions (67 patients), and CCI1 h, after 195 transfusions (55 patients), with pretransfusion PLT counts of not greater than 20 x 10(9) per mL.

RESULTS

Storage experiments showed that the pH of LR-PCs remained greater than 6.8 for 8 days, provided that the PLT concentration was less than 1.3 x 10(9) per mL. Routinely produced LR-PCs had a volume of 282 +/- 15 mL (n = 10,193) and contained 329 x 10(9)+/- 40 x 10(9) PLTs (n = 3467). For 7-day-old LR-PCs, 76 of 78 (97%) of the transfusions resulted in a CI1 h of at least 10 and 37 of 39 (95%) in a CCI1 h of at least 7.5, which indicated levels for successfulness. Mean +/- SE values of CI1 h and CCI1 h of 7-day-old LR-PCs were 28.7 +/- 2.3 (n = 78) and 19.0 +/- 2.0 (n = 39), respectively. No significant differences were observed between 5- and 7-day-old LR-PCs transfused with respect to CI1 h and CCI1 h values.

CONCLUSION

In vitro and in vivo studies showed that LR-PCs can be stored for up to 7 days with excellent clinical results, provided that they are routinely screened for bacterial contamination.

The use of a bacteria detection system to evaluate bacterial contamination in PLT concentrates

BACKGROUND

Random-donor PLTs (RDPs) are functional at 7 days. Nevertheless, since the mid-1980s, concern for bacterial contamination has caused the storage period to be reduced to 5 days. The ability of a bacteria detection system (BDS, Pall) to determine bacterial contamination and permit extension of the PLT shelf life to 7 days was assessed.

STUDY DESIGN AND METHODS

Blood was collected into CP2D and leukoreduced RDPs were prepared. Upon arrival at the hospital, a 2- to 3-mL aliquot was removed from each RDP and introduced into the Pall BDS pouch with a sterile docking device. The pouch was incubated at 37 degrees C for 24 hours and then the oxygen content was measured to determine bacterial contamination. Additionally, the RDPs were pooled and an aliquot was removed for culture with standard manual techniques. CCIs were calculated 1 hour after infusion.

RESULTS

A total of 12,062 individual RDPs were tested. The Pall BDS detected bacteria in 5 units. All of these were positive on repeat sampling. Propionibacterium acnes, coagulase-negative Staphylococcus, and Bacillus species were confirmed by manual technique in 3 units, one could not be identified, and one was negative. Aliquots from PLT pools were positive in 80 of 2201 pools when tested by manual methods. Of these, 79 were false-positives and 1 unit contained coagulase-negative Staphylococcus. The Pall BDS was easy to use and required less than 5 minutes for all manipulations. After 7 days of storage, the PLTs gave an average CCI of 16 x 10(11)+/- 3.39 x 10(11) 1 hour after transfusion (n = 9).

CONCLUSIONS

The Pall BDS permits evaluation of RDPs for bacterial contamination. Culture-negative PLTs were successfully transfused in our institution up to and including 7 days after storage with good CCIs.

Evaluation of the 3D BacT/ALERT automated culture system for the detection of microbial contamination of platelet concentrates

Bacterial transmission remains the major component of morbidity and mortality associated with transfusion-transmitted infections. Platelet concentrates are the most common cause of bacterial transmission. The BacT/ALERT 3D automated blood culture system has the potential to screen platelet concentrates for the presence of bacteria. Evaluation of this system was performed by spiking day 2 apheresis platelet units with individual bacterial isolates at final concentrations of 10 and 100 colony-forming units (cfu) mL-1. Fifteen organisms were used which had been cited in platelet transmission and monitoring studies. BacT/ALERT times to detection were compared with thioglycollate broth cultures, and the performance of five types of BacT/ALERT culture bottles was evaluated. Sampling was performed immediately after the inoculation of the units, and 10 replicates were performed per organism concentration for each of the five types of BacT/ALERT bottles. The mean times for the detection of these 15 organisms by BacT/ALERT, with the exception of Propionibacterium acnes, ranged from 9.1 to 48.1 h (all 10 replicates were positive). In comparison, the time range found using thioglycollate was 12.0-32.3 h (all 10 replicates were positive). P. acnes' BacT/ALERT mean detection times ranged from 89.0 to 177.6 h compared with 75.6-86.4 h for the thioglycollate broth. BacT/ALERT, with the exception of P. acnes, which has dubious clinical significance, gave equivalent or shorter detection times when compared with the thioglycollate broth system. The BacT/ALERT system detected a range of organisms at levels of 10 and 100 cfu mL-1. This study validates the BacT/ALERT microbial detection system for screening platelets. Currently, the system is the only practically viable option available for routinely screening platelet concentrates to prevent bacterial transmission.

Binding of activated platelets to WBCs in vivo after transfusion

BACKGROUND

During preparation and storage of apheresis concentrates, platelets are being activated. One of the alterations that occur during this process is an increased expression of P-selectin (CD62p) on the cytoplasmic surface of platelets. This neoepitope represents a ligand for the binding of platelets to WBCs. It has been suggested that the activation of platelets is associated with the sequestration of platelets after transfusion. In this in vivo study, the binding of platelets to WBCs was analyzed following transfusion of platelet concentrates (PCs).

STUDY DESIGN AND METHODS

Double apheresis concentrates were prepared with two different cell separators. One of the split products was stored for 1 to 2 days and the other one for 3 to 5 days. Flow cytometry was applied to analyze the degree of platelet activation in vitro, and also to measure the extent of platelet binding to WBC subclasses in vivo after transfusion into patients.

RESULTS

The results of this study show that platelet activation occurs during apheresis and storage of PCs. After transfusion of the PCs, no significant binding of platelets to T or B-cells could be detected. However, a significant binding of platelets to monocytes and neutrophil granulocytes occurs. While in Baxter PCs stored for 1-2 days the amount of platelet-leukocyte aggregates in vivo was higher compared to COBE PCs, no such difference could be detected anymore for the PCs stored for 3-5 days.

CONCLUSION

This study demonstrates that binding of activated platelets occurs to monocytes and neutrophil granulocytes but not to T- and B-cells in the circulation after transfusion. In addition, the interaction of platelets and WBCs is dependent on the degree of P-selectin expression. Platelets showing a higher degree of activation adhere to WBCs to a higher degree than nonactivated platelets.

Experience with universal bacterial culturing to detect contamination of apheresis platelet units in a hospital transfusion service

BACKGROUND

Bacterial contamination of platelet units poses one of the greatest risks of morbidity and mortality to platelet transfusion recipients. A routine culture of all units (WBC-reduced apheresis platelet units) was instituted on Day 2 over a 2-year period to reduce this risk.

STUDY DESIGN AND METHODS

A sterile connecting device was used to attach a small transfer pack on the morning of Day 2 after collection, and 10 mL of the unit were transferred to the small bag. After disconnection from the unit, about half of this volume was transferred to an aerobic culture bottle of an automated bacterial detection system. Units were maintained in available inventory until and unless a report was received of growth in the sample. When available, the unit or a retained aliquot was recultured if the initial sample was positive. Units were held up to 2 days beyond their 5-day outdate and used for transfusion if no other suitable units were available to meet the clinical need or were evaluated with in vitro testing on Day 8.

RESULTS

Of 2678 units cultured, 16 (0.6%) were positive on initial culture. Thirteen could be recultured, and all of these samples were negative. Shortly after the 2-year period of the study, two units (split from the same collection) were documented as growing coagulase-negative Staphylococci 12 hours after sampling. Units transfused on Day 6 or 7 (n = 40) yielded expected clinical responses, and CCI available on 21 cipients 10 to 60 minutes after transfusion demonstrated acceptable results (mean, 14,400 +/- 8800; median, 12,191; 90% > 7500). More than 96 percent of units tested on Day 8 had pH greater than 6.2 and continued to demonstrate swirling.

CONCLUSIONS

Routine culturing of apheresis platelet units is feasible, can be accomplished with a low rate of false positivity, and can detect contaminated units. The cost of such a protocol could be mitigated with extension of the storage period, and clinical experience with units held for 6 or 7 days was satisfactory.

Transfusion-related bacterial sepsis

Transfusion-associated bacterial sepsis is a persistent problem in transfusion medicine, posing a greater threat than the combined risks of receiving a blood product contaminated with HIV-1 or 2, hepatitis C virus (HCV), hepatitis B virus (HBV), and human T-cell lymphtrophic virus (HTVL) -I or -II. This article provides a brief overview of the current incidence, clinical presentation, associated blood products and organisms, and the most feasible and effective methods available to reduce the potential risk of transfusion-associated sepsis. Because bacterial contamination of blood products is the most frequent cause of transfusion-transmitted infectious disease, and as no single existing strategy can completely eliminate its risk, it is important that clinical suspicion be high, and any partial solutions additively be implemented.

The evaluation of microbial contamination in platelet concentrates prepared by two different methods

The microbial contamination of platelet concentrates (PCs) prepared by two different methods both with a high risk of bacterial contamination during preparation and storage were evaluated. For apheresis platelets, the concentrates were obtained using the Haemonetics MCS 3P device. For the random method, platelets were obtained by two phase centrifugation, in the Heraeus Cryofuge 8500 I device using the Kansuk 3-way bags which permit storage for five days. 1620 plateletpheresis units prepared by apheresis, and 9838 units prepared by the random method, were included in the study. Of the 11,458 PCs studied. 32 (0.27%) were false positives and 24 (0.2%) were real positives. All of the positive results occurred in platelets prepared by the random method. C. xerosis and S. epidermidis, S. hominis, Alpha-hemolytic streptococci, all flora of the skin, were isolated in the contaminated concentrates. The risk of microbial contamination of PCs, prepared both by apheresis and from whole blood, continues at a low rate although the products were collected into specific bags following rules including appropriate disinfection of the skin, correct centrifugation collection time and optimal storage conditions including temperature and agitation. These results again emphasize the importance of: obeying phlebotomy rules and hand disinfection of the person who collects the blood as well as the need for careful skin decontamination of the donor, during donation.

Evaluation of an automated culture system for detecting bacterial contamination of platelets: an analysis with 15 contaminating organisms

BACKGROUND

Approximately 1 in 2000 platelet components are bacterially contaminated. The time to detection of 15 seeded organisms in platelets recovered from an automated culture system was studied.

STUDY DESIGN AND METHODS

Isolates of Bacillus cereus, Bacillus subtilis, Candida albicans, Clostridium perfringens, Corynebacterium species, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Propionibacterium acnes, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Serratia marcescens, Streptococcus pyogenes, and Streptococcus viridans were inoculated into Day 2 apheresis platelet components to obtain a final concentration of approximately 10 and 100 CFU per mL (2 units/organism). Each bag was sampled 10 times (20 mL/sample). Four mL of each sample was inoculated into standard aerobic and anaerobic bottles and into aerobic and anaerobic bottles containing charcoal; 2 mL was inoculated into pediatric aerobic bottles (so as to maintain a 1:10 ratio of sample to media) and 1 mL into thioglycollate broth.

RESULTS

With the exception of P. acnes, all organisms were detected in a mean of 9.2 to 25.6 hours. A range of 10 serial dilutions in inoculating concentrations was associated with an overall 10.1-percent difference in detection time. A mean of 74.4 and 86.2 hours (100 and 10 CFU/mL inocula, respectively) was required for the detection of P. acnes in anaerobic bottles.

CONCLUSION

Bacteria thought to be clinically significant platelet contaminants can be detected in 9.2 to 25.6 hours when the starting concentration is approximately 10 to 100 CFU per mL. P. acnes required considerably longer incubation times for detection (in either aerobic or anaerobic bottles). However, P. acnes is of questionable clinical significance. Such a detection system could be used in either a blood collection center or a transfusion service to screen platelet concentrates for bacterial contamination. Such testing (with sterile sampling performed so as to maintain a closed-bag system) would be expected to save lives and might allow an extension of platelet storage.

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.

Complement activation during storage of single-donor platelet concentrates

Single-donor platelets are stored up to 5 days prior to transfusion. Since contact of plasma to plastic surfaces may lead to complement activation, we investigated whether there is any increase in the complement factors C3a, C4a and C5a in routinely stored single-donor platelet concentrates. C3a levels increased about 40-fold during a 7-day storage. C4a levels also increased with storage time but to a lesser extent. By contrast, C5a levels remained stable throughout this period. ADP- and collagen-induced aggregation was impaired after storage of platelets, indicating severe functional injury. In platelet-poor plasma stored under identical conditions a comparable increase in C3a and C4a concentrations was observed. The loss of platelet function during storage might at least in part be due to the excessive anaphylatoxin concentrations observed.

The selection of plastic materials for blood bags

The procedures used in the preparation of blood components together with the processes used in the manufacture of multiple blood bag systems impose a unique combination of requirements that severely limits the selection of plastics. Plasticized PVC, the plastic used in the first blood bags introduced by Carl Walter over 40 years ago, remains the material of choice today. Blood bag material research has focused on two areas: (1) the development of containers with increased gas permeability for the storage of platelet concentrates; and (2) the reduction or elimination of plasticizer contamination of stored blood components. This research has led to the development of several second-generation containers that have improved the quality and extended the allowable storage period of platelet transfusion products. Plastics virtually free of extractives are available for the storage of platelets and plasma, but elimination of plasticizers from RBC products has not yet been achieved.

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.

Staphylococcus epidermidis bacteremia from transfusion of contaminated platelets: application of bacterial DNA analysis

Septicemia is a rare complication of platelet transfusion. A case is reported of transfusion-associated septicemia in a 66-year-old man who received a 10-unit pool of platelets. During transfusion, he experienced rigors, wheezing, dyspnea, and fever. A total of four blood cultures drawn 10 and 36 hours after discontinuation of the transfusion grew Staphylococcus epidermidis. Culture of the residual platelet pool yielded S. epidermidis with a colony count of 10(5) organisms per mL. Strain identity of all four blood isolates and the platelet pool isolate was confirmed by gel electrophoresis of EcoRI and HindIII restriction digests of whole-cell DNA. There have been 31 prior reported cases of platelet transfusion-associated septicemia, of which 9 have been caused by coagulase-negative staphylococci. Systemic reactions to platelet transfusions should prompt consideration of transfusion-associated bacteremia as the cause.

Concepts about current conditions for the preparation and storage of platelets

Substantial experimentation over the last 20 years has led to the conditions that are currently used to prepare and store platelets. Although platelet rich plasma is used in most instances to prepare platelet concentrates, there may be some benefit associated with the use of buffy coats as the source component. Extension of the maximum allowable storage time for platelets to 5 days has been possible as a result of defining the conditions which allow for the better retention of platelet properties. Storage temperature, permeability of the storage container, volume of platelet suspension, and the need to agitate platelets have been identified as key parameters that maintain platelet viability and functional properties. Storage in the 20 to 24 degrees C range prevents a reduction in posttransfusion viability that occurs when platelets are maintained at lower temperatures. Adequate influx of oxygen through container walls to support platelet metabolism and, to a lesser degree, adequate efflux of produced carbon dioxide are essential for maintaining pH levels, a key parameter that also influences posttransfusion viability. Permeability is influenced by container size and material, by use of a satisfactory volume of plasma and by agitating the container. Although platelet concentrates prepared from whole blood have been primarily used to delineate appropriate storage conditions, they also apply to platelets harvested by aphersis technology. Storage under currently used conditions, although providing products with acceptable clinical efficacy, is associated with a reduction in viability and functional characteristics. The development of storage media, specific for platelets, may minimize the occurrence of deleterious changes.

Leaching of plasticizers from and surface characterization of PVC blood platelet bags

The leaching of phthalate plasticizers from four types of blood platelet bags was investigated. The anticoagulant solutions used in the blood collection bags had pH values of 5.64 +/- .04 and contained no detectable amounts of phthalates. Platelet bag materials from each bag were soaked in normal salines for up to 5 days. The salines were tested for the leached phthalates from the bags but none could be found. However, di-(2-ethylhexyl) phthalate (DEHP) leached out of the PL-146 and Terumo bags into bovine calf serum used for soaking the bag materials. There was an increase in the amount of DEHP leached from about 1.1 mg at the end of one day to about 3.3 mg per gm of bag material at the end of a five day extraction with the serum. In PL-732 sets, a platelet bag made of a specialty polyolefin, the amount of DEHP leached out was less than 0.02 mg per g of bag material. CLX bags, which contained tri-(2-ethylhexyl) trimelliate (TETM) as a plasticizer, showed a negligible amount of it leaching into the calf serum. Infra-red spectra showed that PL-146 bags had been coated with a layer of a fatty acid amide while the Terumo bags contained a layer of a silicone fluid on their inner surfaces. CLX bags showed a coating of stearates, which were probably soaps of calcium or zinc. Scanning electron microscopy (SEM) showed that the inner surfaces of each brand of the bag were distinctly different morphologically. The two PVC bags were very similar whereas the surfaces morphology of PL-732 was rougher. Terumo bag had a different surface morphology than those of the other bags whereas the CLX bags had a very regular surface pattern. The exact significance of the surface morphology is not certain but excessively rough surfaces may not be desirable for the bags.

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.

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.

Preparation of leukocyte-poor platelet concentrates from buffy coats. III. Effect of leukocyte contamination on storage conditions

To study the influence of contaminating leukocytes on the storage conditions of platelet concentrates (PC), various amounts of leukocytes were added to identical PC. From 12 blood donations, 12 leukocyte-poor PC were prepared and pooled. Subsequently, the pool was divided into 12 identical PC. The plasma volume of the PC was 58.6 +/- 0.6 ml, the platelet concentration was 1.01 +/- 0.04 x 10(9)/ml (mean +/- SD) and the red cell contamination did not exceed 10(7) per PC. To 4 groups of 3 PC, pooled leukocytes were added from the same 12 blood donations. The leukocyte contamination for each group of 3 PC was 0.14 +/- 0.05, 1.96 +/- 0.09, 5.53 +/- 0.98 and 13.0 +/- 0.93 x 10(6)/ml (mean +/- SD) for groups I-IV, respectively. The PC were stored for 7 days at 22 degrees C in normal polyvinylchloride bags. A significant correlation was found between increasing concentrations of leukocytes in the PC and the drop in pH (r = -0.93), glucose consumption (r = -0.91), lactic acid production (r = 0.93) and release of lactate dehydrogenase (r = 0.92) during storage of the PC. The excretion of beta-thromboglobulin, depletion of platelet adenine nucleotides, decreased ability to incorporate 3H-adenosine into metabolic nucleotides and poor morphology of the platelets were also significantly correlated with an increased number of leukocytes in the PC. These data show that high concentrations of leukocytes in PC have a significant detrimental effect on the viability of platelets during storage at 22 degrees C. We conclude that for good storage conditions of PC, the upper limit of leukocytes per PC should not exceed 10(7).

Effects of autoclave sterilization on the physical properties of storage bags and granulocyte function

Autoclave sterilization altered the leaching of plasticizer, CO2 gas permeability, surface area and the surface wettability of bag films. These changes affected granulocyte cell counts and functions during storage. Four types of polyvinyl chloride bags, with di-(2-ethylhexyl)phthalate (DEHP) or tri-(2-ethylhexyl)trimellitate (TOTM) as plasticizer, with or without treatment by glow discharge (H2), were sterilized with ethylene oxide (EO) or autoclaving (AC). The greatest amounts of plasticizer leached from DEHP-EO bags. TOTM plasticizer did not leach into plasma. CO2 gas permeability was greater with TOTM than DEHP. AC sterilization decreased the surface area of bags. Wettability of film surfaces was greatest with H2-TOTM-EO. After storage in these bags for 24 and 48 h at 22 degrees C, the granulocyte cell counts and functions were greatest in H2-TOTM-EO bags with the nonleaching plasticizer, higher CO2 gas permeability and higher wettable surface due to glow-discharge treatment. The H2-TOTM-EO bag was useful as a granulocyte storage container.

Extended storage of single-donor apheresis platelets in CLX blood bags: effect of storage on platelet morphology, viability and in vitro function

A CLX (Cutter Laboratories, Berkeley, Calif.) bag system was evaluated for storage of single-donor apheresis platelets collected with the Haemonetics V-50 blood processor. Concentrates (n = 21) containing 3.9-5.2 x 10(11) platelets in 292 (+/- 41.8) ml were stored in two 1-liter bags for 7 days at 22 degrees C. pH was well maintained, declining from an initial pH of 7.0 (+/- 0.04) to 6.92 (+/- 0.20) after 7 days. Platelet morphology, response to a hypotonic stimulus and aggregation induced by paired agonists (epinephrine and ADP, or collagen) were also well-preserved. Concentrates with a wide variation of platelet yields (2.0 greater than or equal to 5.2 x 10(11), n = 43) also maintained pH (6.96 +/- 0.26), morphology and aggregation when stored for 7 days. All platelet concentrates (n = 64) were sterile at collection. Single-donor apheresis platelets may be stored in this bag system for up to 7 days.

Preparation of leukocyte-poor platelet concentrates from buffy coats. II. Lack of effect on storage of different plastics

Six citrate phosphate dextrose (CPD)-saline adenine glucose mannitol (SAG M) quadruple systems were evaluated for the preparation and storage of leukocyte-poor platelet concentrates (PC) from buffy coats. The platelet storage bags examined were manufactured from normal polyvinylchloride (PVC) or special-type plastics. Biotest supplied PVC 76 (n = 14) and PVC 763 (n = 16) NPBI supplied PSV 3277 (n = 15) and DPL-110 (n = 14) and Terumo supplied Teruflex (n = 18) and molded Teruflex (n = 14). The PC were stored for 7 days at 22 degrees C on a horizontally shaking platform. Cell counts, pH, PO2, PCO2, morphology score and swirling patterns were monitored at 5, 72, 120 and 168 h. The plasma volumes averaged 63 ml and ranged from 39 to 81 ml, the overall mean +/- SD platelet concentration was 0.89 +/- 0.33 X 10(9)/ml. None of the PC had a leukoyte count higher than 10 X 10(6) per unit. After storage for 168 h, the pH ranged from 6.56 to 7.40 for all brands. The PO2 remained stable and even rose significantly (p less than 0.05) during storage in the NPBI PSV 3277 and Terumo molded Teruflex bags. The PCO2 decreased equally in all bags. Morphology scores were well maintained in 98% of all PC for up to 120 h, and in 83% at 168 h. A swirling pattern score of 2.5 or greater predicted with a specificity of 100% a good morphology score in the PC.(ABSTRACT TRUNCATED AT 250 WORDS)

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)

Effects of plasticizers and plastic bags on granulocyte function during storage

The influence of the plasticizers, di-(2-ethylhexyl)phthalate (DEHP) and tri-(2-ethylhexyl)trimellitate (TOTM), on granulocyte function was examined. Polyvinyl chloride (PVC) bags with DEHP (DEHP-PVC) leaked DEHP into plasma, but TOTM did not dissolve in plasma under the same conditions. Glow discharge treatment inhibited the leakage of DEHP from DEHP-PVC bags. Depending on the amount of DEHP added into granulocyte suspension, chemotaxis and bactericidal activity decreased, but cell counts and phagocytosis were not affected. During storage for 24 h at 22 degrees C, granulocyte function decreased greatly in DEHP-PVC, but was well maintained in the bags which did not leak plasticizers, TOTM-PVC and glow-discharged DEHP-PVC.

Improved in vivo and in vitro viability of platelet concentrates stored for seven days in a platelet additive solution

An additive solution has been developed for storage of platelet concentrates (PC) which sustains improved in vivo and in vitro viability after 7 d of storage in second generation oxygen permeable containers. This platelet additive solution is a protein-free physiologic salt solution fortified with citrate, bicarbonate and glucose. The in vivo quality of the PC was evaluated by autologous radiolabelling with Indium-111-oxine to measure recovery and survival by multiple hit analysis. The in vitro quality was evaluated by total ATP content, hypotonic shock response and extent of shape change with ADP. Ten paired studies were performed with PC from the same donor being stored for 7 d at 22 degrees C in both CPDA-1 plasma and the additive solution. Mean recoveries and survivals were found to be substantially higher with PC stored in the additive solution than with PC stored in CPDA-1 plasma (51.0 +/- 7.8% and 144.1 +/- 15.9 h versus 36.6 +/- 10.7% and 110.4 +/- 31.6 h). The differences were statistically significant (P less than 0.001). The results of the in vitro assays described above parallelled the in vivo results, with statistically significantly superior results (P less than 0.01) for all parameters of PC stored in the additive solution. This study is the first to show that PC quality may be improved and storage extended using an additive solution.

Storage of platelet concentrates--an in vitro study of four types of plastic packs

Four types of plastic blood collection packs were studied for their ability to preserve platelet function during a 5 d storage period. The platelet concentrates were stored in polyvinyl chloride (Tuta Laboratories), PL 1240 and PL 732 (Fenwal Laboratories) and CLX (Cutter Laboratories) packs, on a Fenwal elliptical rotator at 20 degrees-24 degrees C. Plasma pH, lactate concentration, hypotonic shock response (HSR), platelet aggregation in response to ADP, collagen and ristocetin and levels of the plasticisers, di-2-ethylhexyl phthalate (DEHP) and tri-ethylhexyl trimellitate (TEHTM), were measured. Morphological changes were assessed by electron microscopy. No significant fall in pH occurred in any type of pack but in vitro function and platelet morphology was generally better preserved in Tuta and CLX packs than in PL 732 and PL 1240. Very little TEHTM leached out of the PL 1240 and CLX packs whereas the mean concentration of DEHP in the platelet concentrates stored in Tuta packs was 27.4 mg/100 ml plasma after 5 d of storage. The results indicate that it is possible to prepare and store platelet concentrates in polyvinyl chloride plastic packs for a period of 5 d and maintain their function and viability.

Cryopreservation of human platelets and bone marrow and peripheral blood totipotential mononuclear stem cells

Human platelets in sufficient numbers for a therapeutic transfusion can be collected for preservation either by pooling ABO- and Rh-compatible platelets or by apheresis procedures using mechanical cell-separating machines. Human platelets have been frozen successfully with 5 or 6% dimethyl sulfoxide (DMSO) and stored at -150 or -180 degrees C, respectively. Platelets frozen with 5% DMSO have been stored at -150 degrees C for at least 3 years, and platelets frozen with 6% DMSO have been stored at -80 degrees C for at least 2 years. Approximately 95% of the DMSO usually is removed by washing the platelets after thawing, and the residual DMSO produces no untoward effects. Washed platelets resuspended in plasma can be stored at room temperature for 6 to 8 hr before transfusion. Platelets thus frozen have freeze-thaw-wash recovery values of about 80%. In vivo survival values are only about 50% those seen with fresh platelets, and it is necessary to transfuse twice as many to achieve comparable results. Studies have shown that these platelets have satisfactory circulation, reduce clinical bleeding, and shorten the prolonged bleeding times associated with thrombocytopenia. Studies are now being made on human bone marrow and peripheral blood, from which totipotential cells devoid of immunocompetent cells can be isolated and frozen.

Evaluation of flatbed reciprocal motion agitators for resuspension of stored platelet concentrates

We studied the storage characteristics of platelet concentrates prepared in polyolefin (PL-732) and thin-film polyvinyl chloride (CLX) plastic bags and stored on a newly designed flatbed reciprocal motion agitator with a 1.5 inch (3.8 cm) lateral movement and an oscillation frequency of 70 cycles/min. We also studied the ability of this device to resuspend the platelet button formed after preparative centrifugation. Results showed that platelet concentrates stored on the 1.5-inch shaker had storage characteristics equivalent to those reported for the conventional 70 cycles/min, 1-inch (2.5-cm) lateral movement flatbed shaker. Due to a more rapid acceleration and deceleration rate, however, the 1.5-inch shaker resuspended the platelet button formed after preparative centrifugation much more efficiently than did the less dynamic 1-inch shaker. Furthermore, with either agitator, platelet aggregates in the CLX bag were more readily resuspended than were aggregates in the PL-732 bag due in part to differences in plastic bag wall elasticity.

Continuous-flow techniques for platelet concentrate collection: a step toward standardization and yield predictability

This study chronicles leukocyte- and erythrocyte-depleted platelet concentrate collection by a dual stage channel in which three variables: 1) donor peripheral blood platelet concentration, 2) total blood processed, and 3) collection volume were statistically correlated with platelet yield as determined by a multiple regression analysis of single variables. Platelet concentration in the final yield was related to donor precount and collection rate, and could be varied as indicated for individual applications. Total blood processed was established by procedure time, which in turn was defined by citrate-induced calcium changes in the donor. Reduction in peripheral blood platelet concentration averaged 24% for a mean platelet yield of 3.8 X 10(11). An average of 40% of transfused platelet concentrates were recovered in recipient peripheral blood 1 hr posttransfusion and were hemostatically effective, as determined by correction of bleeding time. Platelet yields and patient response were sustained during current collection procedures, verifying the principles described during the investigative period.