Manufacturing variables and hemostatic function of cold-stored platelets: a systematic review of the literature

A safety and feasibility analysis on the use of cold-stored platelets in combat trauma

BACKGROUND

Damage-control resuscitation has come full circle, with the use of whole blood and balanced components. Lack of platelet availability may limit effective damage-control resuscitation. Platelets are typically stored and transfused at room temperature and have a short shelf-life, while cold-stored platelets (CSPs) have the advantage of a longer shelf-life. The US military introduced CSPs into the battlefield surgical environment in 2016. This study is a safety analysis for the use of CSPs in battlefield trauma.

METHODS

The Department of Defense Trauma Registry and Armed Services Blood Program databases were queried to identify casualties who received room-temperature-stored platelets (RSPs) or both RSPs and CSPs between January 1, 2016, and February 29, 2020. Characteristics of recipients of RSPs and RSPs-CSPs were compared and analyzed.

RESULTS

A total of 274 patients were identified; 131 (47.8%) received RSPs and 143 (52.2%) received RSPs-CSPs. The casualties were mostly male (97.1%), similar in age (31.7 years), with a median Injury Severity Score of 22. There was no difference in survival for recipients of RSPs (88.5%) versus RSPs-CSPs (86.7%; p = 0.645). Adverse events were similar between the two cohorts. Blood products received were higher in the RSPs-CSPs cohort compared with the RSPs cohort. The RSPs-CSPs cohort had more massive transfusion (53.5% vs. 33.5%, p = 0.001). A logistic regression model demonstrated that use of RSPs-CSPs was not associated with mortality, with an adjusted odds ratio of 0.96 (p > 0.9; 95% confidence interval, 0.41-2.25).

CONCLUSION

In this safety analysis of RSPs-CSPs compared with RSPs in a combat setting, survival was similar between the two groups. Given the safety and logistical feasibility, the results support continued use of CSPs in military environments and further research into how to optimize resuscitation strategies.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level IV.

Cold-stored platelet hemostatic capacity is maintained for three weeks of storage and associated with taurine metabolism

BACKGROUND

Platelet (PLT) product transfusion is a life-saving therapy for actively bleeding patients. There is an urgent need to maintain PLT function and extend shelf life to improve outcomes in these patients. Cold-stored PLT (CS-PLT) maintain hemostatic potential better than room temperature-stored PLT (RT-PLT). However, whether function in long-term CS-PLT is maintained under physiological flow regimes and/or determined by cold-induced metabolic changes is unknown.

OBJECTIVES

This study aimed to (i) compare the function of RT-PLT and CS-PLT under physiological flow conditions, (ii) determine whether CS-PLT maintain function after 3 weeks of storage, and (iii) identify metabolic pathways associated with the CS-PLT lesion.

METHODS

We performed phenotypic and functional assessments of RT- and CS-PLT (22 °C and 4 °C storage, respectively; N = 10 unique donors) at storage days 0, 5, and/or 21 via metabolomics, flow cytometry, aggregation, thrombin generation, viscoelastic testing, and a microfluidic assay to measure primary hemostatic function.

RESULTS

Day 21 4 °C PLT formed an occlusive thrombus under arterial shear at a similar rate to day 5 22 °C PLT. Day 21 4 °C PLTs had enhanced thrombin generation capacity compared with day 0 PLT and maintained functionality comparable to day RT-PLT across all assays performed. Key metrics from microfluidic assessment, flow cytometry, thrombin generation, and aggregation were associated with 4 °C storage, and metabolites involved in taurine and purine metabolism significantly correlated with these metrics. Taurine supplementation of PLT during storage improved hemostatic function under flow.

CONCLUSION

CS-PLT stored for 3 weeks maintain hemostatic activity, and storage-induced phenotype and function are associated with taurine and purine metabolism.

Cold platelet transfusion: The effects of a fluid warmer on platelet function

BACKGROUND

Recently the US Food and Drug Administration has granted variances to select blood centers to supply cold-stored platelet components (CSP). In hemorrhage resuscitation warming of blood components with approved fluid warming devices is common.

STUDY DESIGN AND METHODS

Pathogen-reduced apheresis platelet units were collected and stored in one of two ways: (1) CSP-I, (2) CSP-D. CSP-I were collected and immediately stored at 1-6°C until used. CSP-D were collected and stored at 20-24°C for 5 days and transferred to storage at 1-6°C until use. Aggregometry using arachidonic acid (AA), adenosine diphosphate (ADP) and collagen as agonists was performed on the unit samples before and after the units were infused through a Ranger blood-warming device.

RESULTS

CSP-I, 23 units, had very high aggregation responses to all agonists (all ≥47.6 ± 20.7). There was a statistically significant reduction in ADP-induced aggregometry results from 55.1 ± 23.2 before compared to 33.5 ± 14.6 following infusion of the PLT through the blood warmer (p < .001). There were no differences in AA and collagen aggregometry results before and after the infusion of the platelets through the blood warmer. CSP-D had 5 of the 15 units with visible clotting in the bag. The 10 CSP-Ds studied had lower aggregation than all agonists before and after infusion through the blood-warming device (all ≤49.9 ± 35.9).

CONCLUSION

We detected a statistically significant reduction in ADP-induced aggregometry in CSP-I run through a Ranger blood-warming device with no change with AA or collagen agonist aggregometry.

Cold stored platelets in the management of bleeding: is it about bioenergetics?

When platelet concentrates (PCs) were first introduced in the 1960s as a blood component therapy, they were stored in the cold. As platelet transfusion became more important for the treatment of chemotherapy-induced thrombocytopenia, research into ways to increase supply intensified. During the late 1960s/early 1970s, it was demonstrated through radioactive labeling of platelets that room temperature platelets (RTP) had superior post-transfusion recovery and survival compared with cold-stored platelets (CSP). This led to a universal switch to room temperature storage, despite CSP demonstrating superior hemostatic effectiveness upon being transfused. There has been a global resurgence in studies into CSP over the last two decades, with an increase in the use of PC to treat acute bleeding within hospital and pre-hospital care. CSP demonstrate many benefits over RTP, including longer shelf life, decreased bacterial risk and easier logistics for transport, making PC accessible in areas where they have not previously been, such as the battlefield. In addition, CSP are reported to have greater hemostatic function than RTP and are thus potentially better for the treatment of bleeding. This review describes the history of CSP, the functional and metabolic assays used to assess the platelet storage lesion in PC and the current research, benefits and limitations of CSP. We also discuss whether the application of new technology for studying mitochondrial and glycolytic function in PC could provide enhanced understanding of platelet metabolism during storage and thus contribute to the continued improvements in the manufacturing and storage of PC.

Cold stored platelets - Increasing understanding and acceptance

Platelet transfusions decreased the risk of morbidity and mortality secondary to thrombocytopenia. This therapy not only ameliorates platelet loss in bleeding patients,but also those with acquired dysfunction of platelets. The current standard of practice worldwide is to provide room temperature platelets (RTPs); however, there are many disadvantages to the use of RTPs such that alternative approaches have been explored. One potential approach is the integration and use of cold stored platelets (CSP), which are platelets stored at 1-6 °C, in clinical settings. CSP research studies show equivalent hemostasis and platelet dysfunction restoration compared to RTPs. In addition, publications have demonstrated advantages of CSP such as reduced bacterial contamination and wastage. Despite its benefits, the production of CSP by blood centers (BCs) and uptake and use of CSP by hospitals has remained relatively low. This review highlights the rationale for CSP production and strategies for overcoming the implementation challenges faced by BCs based on a literature review.Experiences of Consortium for Blood Availability members to integrate CSP in their BCs and clinical practices by providing variance applications are reviewed in this paper. Also, demonstrated in this manuscript are the current indications and opportunities for CSP utilization by healthcare providers.

Assessment of the soluble proteins HMGB1, CD40L and CD62P during various platelet preparation processes and the storage of platelet concentrates: The BEST collaborative study

BACKGROUND

Structural and biochemical changes in stored platelets are influenced by collection and processing methods. This international study investigates the effects of platelet (PLT) processing and storage conditions on HMGB1, sCD40L, and sCD62P protein levels in platelet concentrate supernatants (PCs).

STUDY DESIGN/METHODS

PC supernatants (n = 3748) were collected by each international centre using identical centrifugation methods (n = 9) and tested centrally using the ELISA/Luminex platform. Apheresis versus the buffy coat (BC-PC) method, plasma storage versus PAS and RT storage versus cold (4°C) were investigated. We focused on PC preparation collecting samples during early (RT: day 1-3; cold: day 1-5) and late (RT: day 4-7; cold: day 7-10) storage time points.

RESULTS

HMGB1, sCD40L, and sCD62P concentrations were similar during early storage periods, regardless of storage solution (BC-PC plasma and BC-PC PAS-E) or temperature. During storage and without PAS, sCD40L and CD62P in BC-PC supernatants increased significantly (+33% and +41%, respectively) depending on storage temperature (22 vs. 4°C). However, without PAS-E, levels decreased significantly (-31% and -20%, respectively), depending on storage temperature (22 vs. 4°C). Contrastingly, the processing method appeared to have greater impact on HMGB1 release versus storage duration. These data highlight increases in these parameters during storage and differences between preparation methods and storage temperatures.

CONCLUSIONS

The HMGB1 release mechanism/intracellular pathways appear to differ from sCD62P and sCD40L. The extent to which these differences affect patient outcomes, particularly post-transfusion platelet increment and adverse events, warrants further investigation in clinical trials with various therapeutic indications.

Cold-stored platelet function is not significantly altered by agitation or manual mixing

BACKGROUND

Cold storage of platelets (CS-PLT), results in better maintained hemostatic function compared to room-temperature stored platelets (RT-PLT), leading to increased interest and use of CS-PLT for actively bleeding patients. However, questions remain on best storage practices for CS-PLT, as agitation of CS-PLT is optional per the United States Food and Drug Administration. CS-PLT storage and handling protocols needed to be determined prior to upcoming clinical trials, and blood banking standard operating procedures need to be updated accordingly for the release of units due to potentially modified aggregate morphology without agitation.

STUDY DESIGN AND METHODS

We visually assessed aggregate formation, then measured surface receptor expression (GPVI, CD42b (GPIbα), CD49 (GPIa/ITGA2), CD41/61 (ITGA2B/ITGB3; GPIIB/GPIIIA; PACI), CD62P, CD63, HLAI), thrombin generation, aggregation (collagen, adenosine diphosphate [ADP], and epinephrine activation), and viscoelastic function (ExTEM, FibTEM) in CS-PLT (Trima collection, 100% plasma) stored for 21 days either with or without agitation (Phase 1, n = 10 donor-paired units) and then without agitation with or without daily manual mixing to minimize aggregate formation and reduce potential effects of sedimentation (Phase 2, n = 10 donor-paired units).

RESULTS

Agitation resulted in macroaggregate formation, whereas no agitation caused film-like sediment. We found no substantial differences in CS-PLT function between storage conditions, as surface receptor expression, thrombin generation, aggregation, and clot formation were relatively similar between intra-Phase storage conditions.

DISCUSSION

Storage duration and not condition impacted phenotype and function. CS-PLT can be stored with or without agitation, and with or without daily mixing and standard metrics of hemostatic function will not be significantly altered.

Gamma and X-ray irradiation do not affect the in vitro quality of refrigerated apheresis platelets in platelet additive solution (PAS-E)

BACKGROUND

Platelet refrigeration (cold storage) provides the advantages of an extended shelf life and reduces the risk of bacterial growth, compared to platelets stored at room temperature (RT). However, processing modifications, such as irradiation, may further improve the safety and/or alter the quality of cold-stored platelets. Platelet components are irradiated to prevent transfusion-associated graft versus host disease (TA-GvHD) in high-risk patients; and while irradiation has little effect on the quality of RT-stored platelet components, there is no data assessing the effect irradiation has following cold storage.

STUDY DESIGN AND METHODS

Triple-dose apheresis platelets were collected in 40% plasma/60% PAS-E, using the TRIMA apheresis platform, and refrigerated (2-6°C) within 8 h of collection. On day 2, one of each component was gamma or X-ray irradiated or remained non-irradiated. Platelets were tested over 21 days.

RESULTS

The platelet concentration decreased by approximately 20% in all groups during 21 days of storage (p > .05). Irradiation (gamma or X-ray) did not affect platelet metabolism, and the pH was maintained above the minimum specification (>6.4) for 21 days. The surface phenotype and the composition of the supernatant was similar in non-irradiated and irradiated platelets, regardless of the source of radiation. Functional responses (aggregation and clot formation) were not affected by irradiation.

DISCUSSION

Gamma and X-ray irradiation do not affect the in vitro quality of platelet components stored in the cold for up to 21 days. This demonstrates the acceptability of irradiating cold-stored platelets, which has the potential to improve their safety for at-risk patient cohorts.

Time from apheresis platelet donation to cold storage: Evaluation of platelet quality and bacterial growth

BACKGROUND

Cold storage reduces posttransfusion survival of platelets; however, it can improve platelet activation, lower risk of bacterial contamination, and extend shelf-life compared to room temperature (RT) storage. To facilitate large-scale availability, manufacturing process optimization is needed, including understanding the impact of variables on platelet potency and safety. Short time requirements from collection to storage is challenging for large blood centers to complete resuspension and qualify platelets for production. This study evaluated the impact of time from platelet component collection to cold storage on in vitro properties and bacterial growth.

STUDY DESIGN AND METHODS

Double-apheresis platelet components were collected from healthy donors, suspended in 65% PAS-III/35% plasma, and split into 2 equal units. One unit was placed into cold storage within 2 h and the other unit after 8 h. Eight matched pairs were evaluated for 12 in vitro parameters. Twenty-four matched pairs were evaluated with 8 bacterial strains tested in triplicate. Samples were tested throughout 21 days of storage.

RESULTS

In vitro properties were not different between 2 and 8 h units, and trends throughout storage were similar between arms. Time to cold storage did not significantly impact bacterial growth, with <1 log₁₀ difference at all timepoints between units.

DISCUSSION

Our studies showed that extending time to cold storage from 2 to 8 h from collection did not significantly increase the bacterial growth, and the platelet component quality and function is maintained. The ability to extend the time required from collection to storage will improve blood center logistics to feasibly produce CSPs.

Whole Blood Administration: Comparison of In Vitro Platelet Function of Pressure Bag, Pressure Bag With Fluid Warming Device, and Rapid Infuser Methods

BACKGROUND

Use of low-titer group O whole blood for emergent transfusion of patients with unknown blood type became AABB approved in January 2018. Since that time, there is increasing use of whole blood in massive transfusion protocols. Whole blood stored at refrigerator temperature (2-4 °C) contains functional platelets that some research proposes may provide better clot dynamics than standard platelets, which are stored at room temperature (20-24 °C). Conventional teaching does not promote infusion of platelet products with pressure or warming, due to concerns of activation and subsequent inactivity of the infused platelets. Although a few reports found no significant changes in platelet function with warming or pressure during infusion of conventional room-temperature-stored platelets, there is limited data to support use of warming or pressure for infusion of whole blood products containing cold-stored platelets.

METHODS

This study design is to evaluate and compare three commonly used methods of administering blood products in a massive transfusion setting for their potential effects on platelets contained within whole blood units (pressure bag alone, pressure bag with fluid warming line, and rapid infuser).

RESULTS

Platelet function of 10 units tested pre- and post-infusion by thromboelastography (TEG) and platelet aggregation studies found no significant difference in platelet activity pre- and post-infusion with any of the three methods evaluated.

CONCLUSIONS

This study supports the use of rapid infuser or pressure bag devices (with or without warming) as acceptable for infusion of whole blood products. Infusion of whole blood with warming is preferable to prevent potential transfusion-associated hypothermia.

Effects of the COVID-19 pandemic on supply and use of blood for transfusion

The COVID-19 pandemic has major implications for blood transfusion. There are uncertain patterns of demand, and transfusion institutions need to plan for reductions in donations and loss of crucial staff because of sickness and public health restrictions. We systematically searched for relevant studies addressing the transfusion chain-from donor, through collection and processing, to patients-to provide a synthesis of the published literature and guidance during times of potential or actual shortage. A reduction in donor numbers has largely been matched by reductions in demand for transfusion. Contingency planning includes prioritisation policies for patients in the event of predicted shortage. A range of strategies maintain ongoing equitable access to blood for transfusion during the pandemic, in addition to providing new therapies such as convalescent plasma. Sharing experience and developing expert consensus on the basis of evolving publications will help transfusion services and hospitals in countries at different stages in the pandemic.

Re-introducing whole blood for transfusion: considerations for blood providers

Whole blood is the original blood preparation but disappeared from the blood bank inventories in the 1980s following the advent of component therapy. In the early 2000s, both military and civilian practice called for changes in the transfusion support for massive haemorrhage. The 'clear fluid' policy was abandoned and replaced by early balanced transfusion of platelets, plasma and red cells. Whole blood is an attractive alternative to multi-component therapy, which offers reduced hemodilution, lower donor exposure and simplified logistics. However, the potential for wider re-introduction of whole blood requires re-evaluation of haemolysins, storage conditions and shelf-life, the need for leucocyte depletion/ pathogen reduction and inventory management for blood providers. This review addresses these questions and calls for research to define the optimal whole blood product and the indications for its use.

Preliminary characterization of the properties of cold-stored apheresis platelets suspended in PAS-III with and without an 8-hour room temperature hold

BACKGROUND

Use of extended cold storage of platelets promises to increase PLT availability and the bacterial safety of bleeding patients. No information is currently available on the preservation of apheresis PLT in vitro quality parameters when PLTs are held at room temperature early in the storage period prior to transfer to cold storage.

STUDY DESIGN AND METHODS

Double units of platelets suspended in 35% plasma/65% PAS-III were collected from normal consenting research donors and rested at room temperature for 1-2 hours. One of the units was then stored at 1-6°C while the other unit was placed on an agitator at 20-24°C. Eight hours after collection, the unit stored at room temperature was transferred to 1-6°C storage without agitation. Units were sampled for an array of PLT in vitro parameters on Days 1, 7, 14, and 21.

RESULTS

As expected, PLTs held for 8 hours at 20-24°C prior to 1-6°C storage had greater lactate levels and reduced glucose levels and pH compared to PLTs subjected to a 1-2-hour room temperature hold prior to cold storage (P < .05). Unexpectedly, platelets held for 8 hours at room temperature had less aggregation response to collagen, ADP, and TRAP compared to PLTs held 1-2 hours at room temperature prior to cold storage (P < .05, n = 8).

CONCLUSION

Decline of aggregation response should be considered when evaluating longer than necessary room temperature holds prior to cold storage of platelets.