Cryopreserved platelets: are we there yet?

Breaking barriers in trauma research: A narrative review of opportunities to leverage veterinary trauma for accelerated translation to clinical solutions for pets and people

Trauma is a common cause of morbidity and mortality in humans and companion animals. Recent efforts in procedural development, training, quality systems, data collection, and research have positively impacted patient outcomes; however, significant unmet need still exists. Coordinated efforts by collaborative, translational, multidisciplinary teams to advance trauma care and improve outcomes have the potential to benefit both human and veterinary patient populations. Strategic use of veterinary clinical trials informed by expertise along the research spectrum (i.e., benchtop discovery, applied science and engineering, large laboratory animal models, clinical veterinary studies, and human randomized trials) can lead to increased therapeutic options for animals while accelerating and enhancing translation by providing early data to reduce the cost and the risk of failed human clinical trials. Active topics of collaboration across the translational continuum include advancements in resuscitation (including austere environments), acute traumatic coagulopathy, trauma-induced coagulopathy, traumatic brain injury, systems biology, and trauma immunology. Mechanisms to improve funding and support innovative team science approaches to current problems in trauma care can accelerate needed, sustainable, and impactful progress in the field. This review article summarizes our current understanding of veterinary and human trauma, thereby identifying knowledge gaps and opportunities for collaborative, translational research to improve multispecies outcomes. This translational trauma group of MDs, PhDs, and DVMs posit that a common understanding of injury patterns and resulting cellular dysregulation in humans and companion animals has the potential to accelerate translation of research findings into clinical solutions.

Cryopreserved platelets washed with a dialysis machine for dimethyl sulphoxide removal

BACKGROUND AND OBJECTIVES

Cryopreserved platelets (cPLTs) can be stored for years and are mainly used in military settings. However, the commonly used cryoprotectant dimethyl sulphoxide (DMSO) has toxic side effects when utilized in high quantities. We developed a novel method to aseptically remove DMSO from thawed cPLTs by dialysis.

MATERIALS AND METHODS

One unit of platelets (N = 6) was mixed with 75 mL of 27% DMSO within 4 days after collection and stored at -80°C for 1 week. The platelet counts, platelet distribution width, mean platelet volume (MPV), platelet activity, platelet release, platelet aggregation, platelet metabolism indicators and platelet ultrastructural features (determined by electron microscopy) of the samples at the pre-freeze, post-thaw wash (post-TW) and 24 h post-thaw wash (24-PTW) stages were determined and compared.

RESULTS

The DMSO clearance rate from the post-TW platelets was 95.56 ± 1.3%, and the platelet recovery rate after washing was 74.66 ± 6.34%. The total count, activity, release factors, aggregation and thrombolytic ability of the post-TW platelets were lower, whereas the MPV and apoptosis rates were higher compared with those of the pre-freeze platelets. The lactic acid, glucose and potassium ions released from the platelets during washing were filtered away by the dialyser, which significantly reduced their concentration. However, 24-PTW platelets were metabolically active, resulting in a decrease in pH and glucose content and an increase in lactic acid content. The level of potassium ions remained low after 24 h of storage and washing. The pre-freeze platelets maintained their normal disc shape and exhibited an open canalicular system (OCS) and a dense tubular system. The cPLTs appeared irregular after washing, with protruding pseudopodia and an extensive OCS, which increased the release of their contents.

CONCLUSION

We developed a novel dialysis method to effectively remove DMSO from cPLTs under aseptic conditions and maintain platelet quality. The clinical efficacy of our method remains to be determined. However, the function of the platelets declined 24 h after washing, making them unsuitable for transfusion.

Platelet Transfusion for Trauma Resuscitation

Purpose of Review

To review the role of platelet transfusion in resuscitation for trauma, including normal platelet function and alterations in behavior following trauma, blood product transfusion ratios and the impact of platelet transfusion on platelet function, platelet function assays, risks of platelet transfusion and considerations for platelet storage, and potential adjunct therapies and synthetic platelets.

Recent Findings

Platelets are a critical component of clot formation and breakdown following injury, and in addition to these hemostatic properties, have a complex role in vascular homeostasis, inflammation, and immune function. Evidence supports that platelets are activated following trauma with several upregulated functions, but under conditions of severe injury and shock are found to be impaired in their hemostatic behaviors. Platelets should be transfused in balanced ratios with red blood cells and plasma during initial trauma resuscitation as this portends improved outcomes including survival. Multiple coagulation assays can be used for goal-directed resuscitation for traumatic hemorrhage; however, these assays each have drawbacks in terms of their ability to measure platelet function. While resuscitation with balanced transfusion ratios is supported by the literature, platelet transfusion carries its own risks such as bacterial infection and lung injury. Platelet supply is also limited, with resource-intensive storage requirements, making exploration of longer-term storage options and novel platelet-based therapeutics attractive. Future focus on a deeper understanding of the biology of platelets following trauma, and on optimization of novel platelet-based therapeutics to maintain hemostatic effects while improving availability should be pursued.

Summary

While platelet function is altered following trauma, platelets should be transfused in balanced ratios during initial resuscitation. Severe injury and shock can impair platelet function, which can persist for several days following the initial trauma. Assays to guide resuscitation following the initial period as well as storage techniques to extend platelet shelf life are important areas of investigation.

Frozen Platelets-Development and Future Directions

Storage requirements and outdating of platelets represent a continued challenge for blood banks. These hurdles are confounded for rural area hospitals or in military deployments. Over 60 years of research and development into frozen platelets have generated a stable and reproducible product. Valeri's method to freeze platelets in 6% dimethyl sulfoxide (DMSO) and storage at -80°C allows for long-term storage alleviating burdens placed on blood banks. Clinical studies show that frozen platelet transfusions are safe with no related thrombotic or other serious adverse events. There are ongoing efforts to demonstrate cryopreserved platelet (CPP) superiority in efficacy studies designed in trauma or cardiac surgery patients. Technical advances in CPP manufacturing including closed system manufacturing, applications of pathogen reduction technology and potency standard characterization add to the appeal of CPP as an alternative to traditional liquid-stored platelets (LP) in settings of supply shortages, mass casualty, active bleeding, rapid provision of HLA-compatible platelets, and remote care.

Transfusion strategies for major haemorrhage in trauma

Trauma is a leading cause of death worldwide in persons under 44 years of age, and uncontrolled haemorrhage is the most common preventable cause of death in this patient group. The transfusion management of trauma haemorrhage is unrecognisable from 20 years ago. Changes in clinical practice have been driven primarily by an increased understanding of the pathophysiology of trauma-induced coagulopathy (TIC), which is associated with poor clinical outcomes, including a 3- to 4-fold increased risk of death. Targeting this coagulopathy alongside changes to surgical and anaesthetic practices (an overarching strategy known as damage control surgery/damage control resuscitation) has led to a significant reduction in mortality rates over the last two decades. This narrative review will discuss the transfusion practices that are currently used for trauma haemorrhage and the evidence that supports these practices.