Platelets derived from fresh and cold‐stored whole blood participate in clot formation in rats with acute traumatic coagulopathy

Comparison of whole blood versus red blood cells and plasma to correct trauma-induced coagulopathy ex vivo

BACKGROUND

Early resuscitation is based on platelet-poor components such as red blood cells and plasma (RBC + P), contributing to platelet dilution and worsening of trauma-induced coagulopathy (TIC). We aimed to compare the ability of cold-stored whole blood (WB) versus RBC + P as a single component to correct TIC.

STUDY DESIGN AND METHODS

Blood samples were collected on admission from trauma patients who required activation of the major hemorrhage protocol at a single UK major trauma center in 2021/2022. Samples were spiked ex vivo with volumes equivalent to two, four, or eight units of WB or RBC + P stored for a maximum of 2 weeks. Thromboelastometry, platelet counting, and multiple electrode aggregometry (MEA) were performed.

RESULTS

Samples from 20 adult trauma patients were analyzed. Median age was 32 years (27-42), 89% were male, 70% had platelet dysfunction (tissue factor-activated ROTEM [EXTEM]-tissue factor-activated ROTEM with cytochalasin D [FIBTEM] clot amplitude at 5 min [A5] ≤ 30 mm), 65% were coagulopathic (EXTEM A5 ≤ 40 mm), and 42% died. EXTEM-FIBTEM A5 was higher following spiking with WB than RBC + P (33 mm, 26-33, vs. 27 mm, 24-30, p < .001). WB-spiking corrected platelet dysfunction in 2 patient samples out of 20, whereas RBC + P increased the frequency of platelet dysfunction (1/20 sample) and TIC (4/20 samples). RBC + P was associated with a dose-dependent deterioration in rotational thromboelastometry (ROTEM) clot strength and dynamics, platelet count, and aggregation in response to multiple agonists compared with WB-spiking, which maintained or partially corrected these abnormalities.

CONCLUSION

Compared with RBC + P, WB better preserves ex vivo platelet-related ROTEM parameters, platelet count, and aggregation, but does not fully correct these common derangements of TIC.

Platelet ultrastructural changes stored at room temperature versus cold storage observed by electron microscopy and structured illumination microscopy

Our study seeks to provide a theoretical foundation for the clinical use of cold-stored platelets (CSPs) by interpreting ultrastructural images and quantitatively analyzing structural changes. CSPs, room temperature-stored platelets (RTPs), and delayed CSPs (delayed-CSPs) were continuously observed using scanning electron microscopy and transmission electron microscopy at eight time points. Super-resolution fluorescence microscopy was employed to observe changes in platelet microtubules and mitochondrial structure and function, whereas platelet counts, metabolism, and relevant functional indicators were measured concurrently. Quantitative statistical analysis of platelet size, morphology, canalicular systems, and five organelles was performed under electron microscopy. In CSPs stored for 1 day, the platelet shape changed from circular or elliptical to spherical, with size decreasing from 2.8 × 2.2 µm to 2.0 × 2.0 µm. CSPs exhibited wrinkling and reorganization of platelet microtubule proteins, with organelles aggregating toward the central region. CSPs stored for 14 days and delayed-CSPs for stored for 10 days exhibited numerous structurally intact and active cells. The percentage of structure-intact active cells was 92% in both groups, respectively. RTPs stored for 5 and 7 days showed minimal changes in size, a normal microtubule skeleton, and were primarily in a resting state. However, RTPs stored for 10 and 14 days displayed swelling, irregular disintegration of the microtubule skeleton, and the presence of membranous structures and vacuolated cells. The percentage of structure-intact active cells was only 45% and 7%, respectively. Our findings confirmed that the maximum storage time of platelets was 5-7 days for RTPs, within 10 days for delayed-CSPs, and 14 days for CSPs.

Genetically engineered transfusable platelets using mRNA lipid nanoparticles

Platelet transfusions are essential for managing bleeding and hemostatic dysfunction and could be expanded as a cell therapy due to the multifunctional role of platelets in various diseases. Creating these cell therapies will require modifying transfusable donor platelets to express therapeutic proteins. However, there are currently no appropriate methods for genetically modifying platelets collected from blood donors. Here, we describe an approach using platelet-optimized lipid nanoparticles containing mRNA (mRNA-LNP) to enable exogenous protein expression in human and rat platelets. Within the library of mRNA-LNP tested, exogenous protein expression did not require nor correlate with platelet activation. Transfected platelets retained hemostatic function and accumulated in regions of vascular damage after transfusion into rats with hemorrhagic shock. We expect this technology will expand the therapeutic potential of platelets.

In Vitro Analysis of Platelet Adhesion, Aggregation, and Surface GP1bα Expression in Stored Refrigerated Whole Blood: A Pilot Study

BACKGROUND

Warm, fresh whole blood (WB) has been used by the US military to treat casualties in Iraq and Afghanistan. Based on data in that setting, cold-stored WB has been used to treat hemorrhagic shock and severe bleeding in civilian trauma patients in the United States. In an exploratory study, we performed serial measurements of WB's composition and platelet function during cold storage. Our hypothesis was that in vitro platelet adhesion and aggregation would decrease over time.

METHODS

WB samples were analyzed on storage days 5, 12, and 19. Hemoglobin, platelet count, blood gas parameters (pH, Po2, Pco2, and Spo2), and lactate were measured at each timepoint. Platelet adhesion and aggregation under high shear were assessed with a platelet function analyzer. Platelet aggregation under low shear was assessed using a lumi-aggregometer. Platelet activation was assessed by measuring dense granule release in response to high-dose thrombin. Platelet GP1bα levels were measured with flow cytometry, as a surrogate for adhesive capacity. Results at the 3 study timepoints were compared using repeat measures analysis of variance and post hoc Tukey tests.

RESULTS

Measurable platelet count decreased from a mean of (163 + 53) × 109 platelets per liter at timepoint 1 to (107 + 32) × 109 at timepoint 3 (P = .02). Mean closure time on the platelet function analyzer (PFA)-100 adenosine diphosphate (ADP)/collagen test increased from 208.7 + 91.5 seconds at timepoint 1 to 390.0 + 148.3 at timepoint 3 (P = .04). Mean peak granule release in response to thrombin decreased significantly from 0.7 + 0.3 nmol at timepoint 1 to 0.4 + 0.3 at timepoint 3 (P = .05). Mean GP1bα surface expression decreased from 232,552.8 + 32,887.0 relative fluorescence units at timepoint 1 to 95,133.3 + 20,759.2 at timepoint 3 (P < .001).

CONCLUSIONS

Our study demonstrated significant decreases in measurable platelet count, platelet adhesion, and aggregation under high shear, platelet activation, and surface GP1bα expression between cold-storage days 5 and 19. Further studies are needed to understand the significance of our findings and to what degree in vivo platelet function recovers after WB transfusion.

Cold storage alters the immune characteristics of platelets and potentiates bacterial-induced aggregation

BACKGROUND AND OBJECTIVES

Cold-stored platelets are currently under clinical evaluation and have been approved for limited clinical use in the United States. Most studies have focused on the haemostatic functionality of cold-stored platelets; however, limited information is available examining changes to their immune function.

MATERIALS AND METHODS

Two buffy-coat-derived platelet components were combined and split into two treatment arms: room temperature (RT)-stored (20-24°C) or refrigerated (cold-stored, 2-6°C). The concentration of select soluble factors was measured in the supernatant using commercial ELISA kits. The abundance of surface receptors associated with immunological function was assessed by flow cytometry. Platelet aggregation was assessed in response to Escherichia coli and Staphylococcus aureus, in the presence and absence of RGDS (blocks active conformation of integrin α₂ β₃ ).

RESULTS

Cold-stored platelet components contained a lower supernatant concentration of C3a, RANTES and PF4. The abundance of surface-bound P-selectin and integrin α₂ β₃ in the activated conformation increased during cold storage. In comparison, the abundance of CD86, CD44, ICAM-2, CD40, TLR1, TLR2, TLR4, TLR3, TLR7 and TLR9 was lower on the surface membrane of cold-stored platelets compared to RT-stored components. Cold-stored platelets exhibited an increased responsiveness to E. coli- and S. aureus-induced aggregation compared to RT-stored platelets. Inhibition of the active conformation of integrin α₂ β₃ using RGDS reduced the potentiation of bacterial-induced aggregation in cold-stored platelets.

CONCLUSION

Our data highlight that cold storage changes the in vitro immune characteristics of platelets, including their sensitivity to bacterial-induced aggregation. Changes in these immune characteristics may have clinical implications post transfusion.

Implementation of a low-titer stored whole blood transfusion program for civilian trauma patients: Early experience and logistical challenges

INTRODUCTION

Cold-stored low titer group O whole blood (LTOWB) is increasingly utilized in the initial resuscitation of exsanguinating trauma patients. We report on our early experience with LTOWB, focusing on logistics, implementation challenges, and outcomes.

METHODS

In February, 2019, LTOWB was incorporated into the massive transfusion protocol (MTP) activated for trauma patients in the emergency department (ED.) Up to 4 units of LTOWB were included in the MTP cooler, depending on availability, and were transfused prior to transfusion of any other blood products from the MTP cooler. Demographics, injury characteristics, and outcomes were obtained, and the logistics of LTOWB availability were reviewed.

RESULTS

Over a 12-month period, MTP was activated for 74 trauma patients. Of those, 38 (51%) MTP included at least one unit of LTOWB, with 19/38 (50%) including 4 LTOWB units. A total of 177 units of LTOWB were purchased during the study period, and of those, 74 (42%) expired before use. Patients who received LTOWB had a similar mortality compared to those who received component therapy (39% vs. 47%; Odds Ratio [95% CI]: 0.7 [0.3, 2.0]; p = 0.72,) however, they were able to achieve a significantly higher plasma:pRBC ratio during the duration of MTP activation (mean [SD] 0.8 [0.2] vs. 0.4 [0.4]; mean difference [95% CI]: 0.4 [0.2, 0.5]; p < 0.01.) CONCLUSIONS: Our early experience with LTOWB transfusion demonstrates feasibility, but also highlights challenges with inventory management. These findings triggered changes to our protocol aiming at minimizing wastage. The use of LTOWB may yield a higher plasma:pRBC ratio early during the resuscitation period. Further investigation is required to explore whether this may yield a survival advantage.

LEVEL OF EVIDENCE

III (Therapeutic/Care Management).

Lessons Learned From the Battlefield and Applicability to Veterinary Medicine - Part 2: Transfusion Advances

Since the inception of recent conflicts in Afghanistan and Iraq, transfusion practices in human military medicine have advanced considerably. Today, US military physicians recognize the need to replace the functionality of lost blood in traumatic hemorrhagic shock and whole blood is now the trauma resuscitation product of choice on the battlefield. Building on wartime experiences, military medicine is now one of the country's strongest advocates for the principle of hemostatic resuscitation using whole blood or balanced blood components as the primary means of resuscitation as early as possibly following severe trauma. Based on strong evidence to support this practice in human combat casualties and in civilian trauma care, military veterinarians strive to practice similar hemostatic resuscitation for injured Military Working Dogs. To this end, canine whole blood has become increasingly available in forward environments, and non-traditional storage options for canine blood and blood components are being explored for use in canine trauma. Blood products with improved shelf-life and ease of use are not only useful for military applications, but may also enable civilian general and specialty practices to more easily incorporate hemostatic resuscitation approaches to canine trauma care.

Effects of Intercept pathogen reduction treatment on extended cold storage of apheresis platelets

BACKGROUND

Platelets pose the greatest transfusion-transmitted infectious risk among blood products. Refrigeration of platelets can mitigate bacterial contamination and extend platelet shelf life. Implementation of pathogen reduction technologies (PRTs) at blood banks has become increasingly popular to protect against emerging and reemerging infectious diseases. In this study, we sought to evaluate the effects of Intercept PRT on platelets collected on different platforms and cold-stored for up to 21 days in plasma and platelet additive solution (PAS).

METHODS

Double-dose apheresis platelets were collected with use of a Trima or Amicus system into either 100% plasma or 65% InterSol PAS/35% plasma and split equally between two bags. One bag served as control, while the other received Intercept PRT treatment. Bags were stored unagitated in the cold and evaluated on Days 1, 7, 14, and 21 to assess platelet metabolism, activation, aggregation, and clot formation and retraction.

RESULTS

By Day 14 of storage, lactate levels reached approximately 13 mmol/L for all samples irrespective of Intercept treatment. Mean clot firmness dropped from the 62.2- to 67.5-mm range (Day 1) to the 28.4- to 51.3-mm range (Day 21), with no differences observed between groups. Clot weights of Intercept-treated Trima/plasma samples were significantly higher than control by Day 14 of storage (P = .004), indicating a reduced clot retraction function. Intercept treatment caused a higher incidence of plasma membrane breakdown in plasma-stored platelets (P = .0013; Trima/plasma Day 14 Control vs Intercept).

CONCLUSIONS

Intercept treatment of platelets and subsequent cold storage, in plasma or PAS, results in comparable platelet metabolism platelets for up to 14 days of storage but altered clotting dynamics. Pathogen-reduced platelets with an extended shelf life would be beneficial for the deployed setting and would greatly impact transfusion practice among civilian transfusion centers.

Quality of Platelets in Stored Whole Blood

Transfusion of whole blood rather than blood components is gaining popularity. It is easy to use, with one transfusion product to administer rather than 3, and is held at one storage temperature. It only contains anticoagulant-preservative solution, while components contain various storage solutions, which in theory may induce dilution coagulopathy. In this review, the quality of platelets in stored whole blood is summarized. In cold-stored whole blood, the platelet count declines by 1% to 2% per day. The responsiveness to various agonists declines during the storage time, but this appears to have a limited impact on clotting time or on clot strength as measured with thromboelastography. Animal studies have confirmed that platelets from stored whole blood participate equally well in clot formation. The recovery of platelets in stored whole blood is acceptable during at least 15 days of storage. The survival of platelets after transfusion is only 1 day, but this is likely to be sufficient for the intended patient group requiring massive transfusions, as the platelets are rapidly consumed in the wound area. In addition to the logistic benefits, there are drawbacks, most importantly having a sufficiently large inventory with an acceptable outdating rate, particularly since massive transfusions are rare, while requiring a lot of whole blood. The positive experience of the United States military with whole blood transfusion is often brought forward for introduction in the civilian blood bank, but patients with trauma are only a small fraction of the civilian population requiring massive transfusions. It needs to be determined whether in the resourceful environment of the hospital, these patients benefit from whole blood transfusions. Optimization of whole blood storage, with focus on platelet quality, needs to be performed to allow extension of the storage time beyond 15 days to a point where the number of units in inventory and outdating can be balanced.

Use of Specialized Pro-Resolving Mediators to Alleviate Cold Platelet Storage Lesion

BACKGROUND

Cold-stored platelets are an attractive option for treatment of actively bleeding patients due to a reduced risk of septic complications and preserved hemostatic function compared to conventional room temperature-stored platelets. However, refrigeration causes increased platelet activation and aggregate formation. Specialized pro-resolving mediators (SPMs), cell signaling mediators biosynthesized from essential fatty acids, have been shown to modulate platelet function and activation. In this study, we sought to determine if SPMs could be used to inhibit cold-stored platelet activation.

METHODS

Platelets were collected from healthy donors (n = 4-7) and treated with SPMs (resolvin E1 [RvE1], maresin 1 [MaR1], and resolvin D2 [RvD2]) or vehicle (VEH; 0.1% EtOH). Platelets were stored without agitation in the cold and assayed on Days 0 and 7 of storage for platelet activation levels using flow cytometry, platelet count, aggregation response using impedance aggregometry, and nucleotide content using mass spectrometry.

RESULTS

Compared to VEH, SPM treatment inhibited GPIb shedding (all compounds), significantly reduced both PS exposure and activation of GPIIb/IIIa receptor (RvD2, MaR1), and preserved aggregation response to TRAP (RvD2, MaR1) after 7 days of storage. Similar to untreated cold-stored platelets, SPM-treated samples did not preserve platelet counts or block the release of P-Selectin. Nucleotide content was unaffected by SPM treatment in cold-stored platelets.

CONCLUSIONS

SPM treatment, particularly Mar1 and RvD2, led to reduced platelet activation and preserved platelet function after 7 days of storage in the cold. Future work is warranted to better elucidate the mechanism of action of SPMs on cold platelet function and activation.

The Israel Defense Forces experience with freeze-dried plasma for the resuscitation of traumatized pediatric patients

BACKGROUND

With the growing recognition of the disadvantages of crystalloid- and colloid-based resuscitation and the advantages of using blood products as the preferred resuscitation fluid, the Israel Defense Forces Medical Corps (IDF-MC) adopted plasma as the primary volume resuscitation regimen in 2013. While data are accumulating for prehospital plasma transfusion, little to no data exist regarding using plasma as a prehospital resuscitation fluid for traumatized pediatric patients.

METHODS

All patients treated by the IDF-MC personnel are recorded in the IDF Trauma Registry, a unique prehospital trauma registry. All patients treated by the IDF advanced life support providers with FDP at the point of injury between April 2013 and June 2018 who were younger than 18 years at the time of injury were included.

RESULTS

Six hundred seventy-nine children were treated by IDF medical providers, of whom 33 (5%) were identified in the IDF Trauma Registry as having received FDP at the point of injury. Most patients (80%) were treated for penetrating injuries. Most patients received one plasma unit. Fifty-four percent of the patients were also treated by Tranexamic Acid (TXA) and 48% were transfused with crystalloids. In 33% of patients, additional life-saving interventions were performed.

CONCLUSION

While the ideal resuscitation fluid for the pediatric population remains to be determined, it seems reasonable to pursue a similar approach to that of applied that for adults. In the IDF-MC, the resuscitation fluid of choice for trauma patients in hemorrhagic shock is freeze-dried plasma transfused at the point of injury. The current study demonstrates the feasibility of FDP administration in the prehospital scenario for injured children and further supports the growing confidence in the use of FDP for the treatment of pediatric trauma patients.

LEVEL OF EVIDENCE

Retrospective descriptive study, level IV.

The effect of platelet storage temperature on haemostatic, immune, and endothelial function: potential for personalised medicine

Reports from both adult and paediatric populations indicate that approximately two-thirds of platelet transfusions are used prophylactically to prevent bleeding, while the remaining one-third are used therapeutically to manage active bleeding. These two indications, prophylactic and therapeutic, serve two very distinct purposes and therefore will have two different functional requirements. In addition, disease aetiology in a given patient may require platelets with different functional characteristics. These characteristics can be derived from the various manufacturing methods used in platelet product production, including collection methods, processing methods, and storage options. The iterative combinations of manufacturing methods can result in a number of unique platelet products with different efficacy and safety profiles, which could potentially be used to benefit patient populations by meeting diverse clinical needs. In particular, cold storage of platelet products causes many biochemical and functional changes, of which the most notable characterised to date include increased haemostatic activity and altered expression of molecules inherent to platelet:leucocyte interactions. The in vivo consequences, both short- and long-term, of these molecular and cellular cold-storage-induced changes have yet to be clearly defined. Elucidation of these mechanisms would potentially reveal unique biologies that could be harnessed to provide more targeted therapies. To this end, in this new era of personalised medicine, perhaps there is an opportunity to provide individual patients with platelet products that are tailored to their clinical condition and the specific indication for transfusion.

Cold-stored whole blood platelet function is preserved in injured children with hemorrhagic shock

BACKGROUND

Recent data demonstrate the safety of uncrossmatched cold-stored whole blood (WB) transfusion in pediatric trauma patients. The hemostatic capabilities of platelets within the cold-stored WB unit have been demonstrated via in vitro studies and animal models. However, platelet function has not been evaluated in pediatric recipients of cold-stored WB transfusions.

METHODS

Injured children, 2 years or older and 10 kg or greater with hemorrhagic shock received up to 30 mL/kg of cold-stored, low titer (<50) anti-A and -B, leukoreduced, group O- WB during their initial resuscitation. Patients were included if (1) they received WB and no conventional platelets, and (2) platelet count and thromboelastography maximum amplitude were measured both before and after transfusion. These data and relevant clinical outcomes (mortality, intensive care unit length of stay [LOS], hospital LOS and ventilator days) were compared to a historical cohort of pediatric trauma patients who received uncrossmatched red blood cells (RBC) and conventional room temperature platelets.

RESULTS

Twenty-two children were included in the study; 14 in the component cohort versus 8 in the WB cohort. Neither posttransfusion platelet count (129 × 109/L vs. 135 × 109/L) nor function (thromboelastography maximum amplitude, 59.5 mm vs. 60.2 mm) differed significantly between children receiving cold-stored platelets within the WB unit versus children who received conventional warm platelets. Median (interquartile range) weight-adjusted platelet transfusion volume in the historical cohort was 4.6 (2.5-7.7) mL/kg vs. 2.4 (1.3-4.0) mL/kg in the WB cohort (p = 0.03). There was no difference between groups in age, race, mechanism of injury, Injury Severity Score, vital signs, and severe traumatic brain injury (TBI). Outcomes, including mortality, intensive care unit LOS, hospital LOS, and ventilator days, were not significantly different between groups.

CONCLUSION

No difference was seen in posttransfusion platelet number or function in severely injured children receiving cold-stored WB platelets as compared to those receiving conventional room temperature-stored platelets. Larger cohorts are required to confirm these findings.

LEVEL OF EVIDENCE

Therapeutic, level IV.

Therapeutic Utility of Cold-Stored Platelets or Cold-Stored Whole Blood for the Bleeding Hematology-Oncology Patient

Bleeding related to thrombocytopenia is common in hematology-oncology patients. Platelets stored at room temperature (RTPs) are the current standard of care. Platelets stored in the cold (CSPs) have enhanced hemostatic function relative to RTPs. CSPs were reported to reduce bleeding in hematology-oncology patients. Recent studies have confirmed the enhanced hemostatic properties of CSPs. CSPs may be the better therapeutic option for this population. CSPs may also offer a preferable immune profile, reduced thrombotic risk, and reduced transfusion-transmitted infection risk. The logistical advantages of CSPs would improve outcomes for many patients who currently cannot access platelet transfusions.