A pilot randomized clinical trial of cryopreserved versus liquid-stored platelet transfusion for bleeding in cardiac surgery: The cryopreserved versus liquid platelet-New Zealand pilot trial

Platelet Storage-Problems, Improvements, and New Perspectives

Platelet transfusions are routine procedures in clinical treatment aimed at preventing bleeding in critically ill patients, including those with cancer, undergoing surgery, or experiencing trauma. However, platelets are susceptible blood cells that require specific storage conditions. The availability of platelet concentrates is limited to five days due to various factors, including the risk of bacterial contamination and the occurrence of physical and functional changes known as platelet storage lesions. In this article, the problems related to platelet storage lesions are categorized into four groups depending on research areas: storage conditions, additive solutions, new testing methods for platelets (proteomic and metabolomic analysis), and extensive data modeling of platelet production (mathematical modeling, statistical analysis, and artificial intelligence). This article provides extensive information on the challenges, potential improvements, and novel perspectives regarding platelet storage.

Temporal dynamics of in vitro hemostatic function in platelets cryopreserved using a novel approach for rapid issuance

BACKGROUND

Current procedures for thawing and issuing of cryopreserved platelets (CPPs) are laborious and have remained challenging in emergency settings such as blood banks and military operations. In this prospective study, a novel processing method designed to facilitate the rapid issuance of CPPs with no postthaw handling required was developed and functionally characterized in parallel with standard CPPs manufactured.

STUDY DESIGN AND METHODS

Double-dose plateletpheresis units (n = 42) were cryopreserved at -80°C in 5%-6% dimethyl sulfoxide to produce matched pairs thawed successively over a 27-month period for comparison between two processing arms. In contrast to the standard CPPs manufactured as standalone units, platelets were frozen in tandem with resuspending plasma in a distinct partition as a single unit in the novel method, herein referred to as tandem CPPs. Postthaw (PT) CPPs from both arms were assessed at PT0-, 12-, and 24-h to measure platelet recovery, R-time (time to clot initiation; min), and maximum amplitude (MA; clot strength; mm) using thromboelastography.

RESULTS

In the overall dataset, mean platelet recovery was higher (p < .0005) for tandem CPPs (83.9%) compared with standard CPPs (73.3%) at PT0; mean R-times were faster (p < .0005) for tandem CPPs (2.5-3.6 min) compared with standard CPPs (3.0-3.8 min); mean MA was higher for tandem CPPs (57.8-59.5 mm) compared with standard CPPs (52.1-55.8 mm) at each postthaw time point (p < .05).

CONCLUSION

Robust temporal dynamics of superior hemostatic functionality were established for tandem CPPs over extended cryopreservation up to 27 months and 24 h of postthaw storage.

The Year in Coagulation and Transfusion: Selected Highlights from 2022

This is an annual review to cover highlights in transfusion and coagulation in patients undergoing cardiovascular surgery. The goal of this article is to provide readers with a focused summary of the most important transfusion and coagulation topics published in 2022. This includes a discussion covering the management of anemia and red blood cell transfusion, the management of factor Xa inhibitors, updates in coagulation testing, updates in the use of factor concentrates, advances in platelet therapy, advances in anticoagulation management of patients on extracorporeal membrane oxygenation and other forms of mechanical circulatory support, and advances in the diagnosis and management of heparin-induced thrombocytopenia.

Cryopreservation affects platelet macromolecular composition over time after thawing and differently impacts on cancer cells behavior in vitro

Cryopreservation affects platelets' function, questioning their use for cancer patients. We aimed to investigate the biochemical events that occur over time after thawing to optimize transfusion timing and evaluate the effect of platelet supernatants on tumor cell behavior in vitro. We compared fresh (Fresh-PLT) with Cryopreserved platelets (Cryo-PLT) at 1 h, 3 h and 6 h after thawing. MCF-7 and HL-60 cells were cultured with Fresh- or 1 h Cryo-PLT supernatants to investigate cell proliferation, migration, and PLT-cell adhesion. We noticed a significant impairment of hemostatic activity accompanied by a post-thaw decrease of CD42b+ , which identifies the CD62P--population. FTIR spectroscopy revealed a decrease in the total protein content together with changes in their conformational structure, which identified two sub-groups: 1) Fresh and 1 h Cryo-PLT; 2) 3 h and 6 h cryo-PLT. Extracellular vesicle shedding and phosphatidylserine externalization (PS) increased after thawing. Cryo-PLT supernatants inhibited cell proliferation, impaired MCF-7 cell migration, and reduced ability to adhere to tumor cells. Within the first 3 hours after thawing, irreversible alterations of biomolecular structure occur in Cryo-PLT. Nevertheless, Cryo-PLT should be considered safe for the transfusion of cancer patients because of their insufficient capability to promote cancer cell proliferation, adhesion, or migration.

Feasibility evaluation of two novel systems for the automated preparation and extended storage of DMSO cryopreserved platelets

BACKGROUND

Manufacturing methods for dimethyl sulfoxide (DMSO)-cryopreserved platelets (CPPs) are manual and labor intensive. Thawing and prepare-for-transfusion steps are in an open system that requires transfusion within 4 h. A fill-and-finish system (CUE) can automate the manufacturing process. A newly configured bag system allows freezing, thawing, and use of resuspension solutions while maintaining the functionally closed system, and extending the post-thaw shelf life beyond 4 h. Our objective is to evaluate the feasibility of the CUE system and the functionally closed bag system.

STUDY DESIGN AND METHODS

DMSO was volumetrically added to double-dose apheresis platelets, concentrated, and delivered to a 50- or 500-mL ethylene-vinyl acetate (EVA) bag by the CUE (n = 12). The functionally closed bag system contained 25 mL platelet additive solution 3 (PAS-3) in a 50-mL EVA bag. Control CPP (n = 2) were manually prepared. PAS-3 and CPP were thawed together. CPP were stored up to 98 h (20-24°C) and tested using a standard assay panel.

RESULTS

CUE prepared CPP met the design targets: volume, platelet content, and DMSO concentration. CUE CPP P-selectin was high. CD42b, phosphatidylserine (PS) expression, and live cell percentage were favorable compared to controls and favorably maintained over storage. The thrombin generation potency was slightly reduced compared to controls. The 50 mL EVA bag maintained pH for up to 30 h, and the 500 mL EVA bag beyond 76 h.

DISCUSSION

The CUE system presents a technically feasible method to prepare CPP. A functionally closed bag system with resuspension solution was successful and can extend the post-thaw storage time of CPP.

Identification of platelet subpopulations in cryopreserved platelet components using multi-colour imaging flow cytometry

Cryopreservation of platelets, at  - 80 °C with 5-6% DMSO, results in externalisation of phosphatidylserine and the formation of extracellular vesicles (EVs), which may mediate their procoagulant function. The phenotypic features of procoagulant platelets overlap with other platelet subpopulations. The aim of this study was to define the phenotype of in vitro generated platelet subpopulations, and subsequently identify the subpopulations present in cryopreserved components. Fresh platelet components (n = 6 in each group) were either unstimulated as a source of resting platelets; or stimulated with thrombin and collagen to generate a mixture of aggregatory and procoagulant platelets; calcium ionophore (A23187) to generate procoagulant platelets; or ABT-737 to generate apoptotic platelets. Platelet components (n = 6) were cryopreserved with DMSO, thawed and resuspended in a unit of thawed plasma. Multi-colour panels of fluorescent antibodies and dyes were used to identify the features of subpopulations by imaging flow cytometry. A combination of annexin-V (AnnV), CD42b, and either PAC1 or CD62P was able to distinguish the four subpopulations. Cryopreserved platelets contained procoagulant platelets (AnnV+/PAC1-/CD42b+/CD62P+) and a novel population (AnnV+/PAC1-/CD42b+/CD62P-) that did not align with the phenotype of aggregatory (AnnV-/PAC1+/CD42b+/CD62P+) or apoptotic (AnnV+/PAC1-/CD42b-/CD62P-) subpopulations. These data suggests that the enhanced haemostatic potential of cryopreserved platelets may be due to the cryo-induced development of procoagulant platelets, and that additional subpopulations may exist.

Cryopreserved platelets in bleeding management in remote hospitals: A clinical feasibility study in Sweden

Background

Balanced transfusions, including platelets, are critical for bleeding patients to maintain hemostasis. Many rural hospitals have no or limited platelet inventory, with several hours of transport time from larger hospitals. This study aimed to evaluate the feasibility of using cryopreserved platelets that can be stored for years, in remote hospitals with no or limited platelet inventory.

Material and methods

Three remote hospitals participated in a prospective study including adult bleeding patients where platelet transfusions were indicated. Cryopreserved platelets were prepared in a university hospital, concentrated in 10 ml, transported on dry ice, and stored at -80°C at the receiving hospital. At request, the concentrated platelet units were thawed and diluted in fresh frozen plasma. The indications, blood transfusion needs, and laboratory parameters pre- and post-transfusion, as well as logistics, such as time from request to transfusion and work efforts in preparing cryopreserved platelets, were evaluated.

Results

Twenty-three bleeding patients were included. Nine patients (39%) were treated for gastrointestinal bleeding, five (22%) for perioperative bleeding, and four (17%) for trauma bleeding. The transfusion needs were 4.9 ± 3.3 red blood cell units, 3.2 ± 2.3 plasma units, and 1.9 ± 2.2 platelet units, whereof cryopreserved were 1.5 ± 1.1 (mean ± SD). One patient had a mild allergic reaction. We could not show the difference in laboratory results between pre- and post-transfusion of the cryopreserved units in the bleeding patients. The mean time from the order of cryopreserved platelets to transfusion was 64 min, with a range from 25 to 180 min.

Conclusion

Cryopreserved platelets in remote hospitals are logistically feasible in the treatment of bleeding. The ability to have platelets in stock reduces the time to platelet transfusion in bleeding patients where the alternative often is many hours delay. Clinical effectiveness and safety previously shown in other studies are supported in this small feasibility study.

Frozen for combat: Quality of deep-frozen thrombocytes, produced and used by The Netherlands Armed Forces 2001-2021

BACKGROUND

The Netherlands Armed Forces (NLAF) are using -80°C deep-frozen thrombocyte concentrate (DTC) since 2001. The aim of this study is to investigate the effect of storage duration and alterations in production/measurement techniques on DTC quality. It is expected that DTC quality is unaffected by storage duration and in compliance with the European guidelines for fresh and cryopreserved platelets.

STUDY DESIGN AND METHODS

Pre-freeze and post-thaw product platelet content and recovery were collected to analyze the effects of dimethyl sulfoxide (DMSO) type, duration of frozen storage (DMSO-1 max 12 years and DMSO-2 frozen DTC max 4 years at -80°C) and type of plasma used to suspend DTC. Coagulation characteristics of thawed DTC, plasma and supernatant of DTC (2× 2500 G) were measured with Kaolin thromboelastography (TEG) and phospholipid (PPL) activity assay.

RESULTS

Platelet content and recovery of DTC is ±10%-15% lower in short-stored products and remained stable when stored beyond 0.5 years. Thawed DTC (n = 1724) were compliant to the European guidelines (98.1% post-thaw product recovery ≥50% from original product, 98.3% ≥200 × 10⁹ platelets/unit). Compared to DMSO-1, products frozen with DMSO-2 showed ±8% reduced thaw-freeze recovery, a higher TEG clot strength (MA 58 [6] vs. 64 [8] mm) and same ±11 s PPL clotting time. The use of cold-stored thawed plasma instead of fresh thawed plasma did not influence product recovery or TEG-MA.

DISCUSSION

Regardless of alterations, product quality was in compliance with European guidelines and unaffected by storage duration up to 12 years of -80°C frozen storage.

Cryopreserved platelets compared with liquid-stored platelets for the treatment of surgical bleeding: protocol for two multicentre randomised controlled blinded non-inferiority trials (the CLIP-II and CLIPNZ-II trials)

INTRODUCTION

Cryopreservation at -80°C in dimethylsulphoxide extends platelet shelf-life from 7 days to 2 years. Only limited comparative trial data supports the safety and effectiveness of cryopreserved platelets as a treatment for surgical bleeding. Cryopreserved platelets are not currently registered for civilian use in most countries.

METHODS AND ANALYSIS

CLIP-II and CLIPNZ-II are harmonised, blinded, multicentre, randomised, controlled clinical non-inferiority trials comparing bleeding, transfusion, safety and cost outcomes associated with cryopreserved platelets versus conventional liquid platelets as treatment for bleeding in cardiac surgery. CLIP-II is planning to enrol patients in 12 tertiary hospitals in Australia; CLIPNZ-II will recruit in five tertiary hospitals in New Zealand. The trials use near-identical protocols aside from details of cryopreserved platelet preparation. Patients identified preoperatively as being at high risk of requiring a platelet transfusion receive up to three units of study platelets if their treating doctor considers platelet transfusion is indicated. The primary endpoint is blood loss through the surgical drains in the 24 hours following intensive care unit (ICU) admission after surgery. Other endpoints are blood loss at other time points, potential complications, adverse reactions, transfusion and fluid requirement, requirement for procoagulant treatments, time to commencement of postoperative anticoagulants, delay between platelet order and commencement of infusion, need for reoperation, laboratory and point-of-care clotting indices, cost, length of mechanical ventilation, ICU and hospital stay, and mortality. Transfusing 202 (CLIP-II) or 228 (CLIPNZ-II) patients with study platelets will provide 90% power to exclude the possibility of greater than 20% inferiority in the primary endpoint. If cryopreserved platelets are not inferior to liquid-stored platelets, the advantages of longer shelf-life would justify rapid change in clinical practice. Cost-effectiveness analyses will be incorporated into each study such that, should clinical non-inferiority compared with standard care be demonstrated, the hospitals in each country that would benefit most from changing to a cryopreserved platelet blood bank will be known.

ETHICS AND DISSEMINATION

CLIP-II was approved by the Austin Health Human Research Ethics Committee (HREC/54406/Austin-2019) and by the Australian Red Cross Lifeblood Ethics Committee (2019#23). CLIPNZ-II was approved by the New Zealand Southern Health and Disability Ethics Committee (21/STH/66). Eligible patients are approached for informed consent at least 1 day prior to surgery. There is no provision for consent provided by a substitute decision-maker. The results of the two trials will be submitted separately for publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBERS

NCT03991481 and ACTRN12621000271808.

Novel blood derived hemostatic agents for bleeding therapy and prophylaxis

PURPOSE OF REVIEW

Hemorrhage is a major cause of preventable death in trauma and cancer. Trauma induced coagulopathy and cancer-associated endotheliopathy remain major therapeutic challenges. Early, aggressive administration of blood-derived products with hypothesized increased clotting potency has been proposed. A series of early- and late-phase clinical trials testing the safety and/or efficacy of lyophilized plasma and new forms of platelet products in humans have provided light on the future of alternative blood component therapies. This review intends to contextualize and provide a critical review of the information provided by these trials.

RECENT FINDINGS

The beneficial effect of existing freeze-dried plasma products may not be as high as initially anticipated when tested in randomized, multicenter clinical trials. A next-generation freeze dried plasma product has shown safety in an early phase clinical trial and other freeze-dried plasma and spray-dried plasma with promising preclinical profiles are embarking in first-in-human trials. New platelet additive solutions and forms of cryopreservation or lyophilization of platelets with long-term shelf-life have demonstrated feasibility and logistical advantages.

SUMMARY

Recent trials have confirmed logistical advantages of modified plasma and platelet products in the treatment or prophylaxis of bleeding. However, their postulated increased potency profile remains unconfirmed.

The haemostatic effect of deep-frozen platelets versus room temperature-stored platelets in the treatment of surgical bleeding: MAFOD—study protocol for a randomized controlled non-inferiority trial

Background

The Netherlands Armed Forces have been successfully using deep-frozen (− 80 °C) thrombocyte concentrate (DTC) for the treatment of (massive) bleeding trauma patients in austere environments since 2001. However, high-quality evidence for the effectiveness and safety of DTCs is currently lacking. Therefore, the MAssive transfusion of Frozen bloOD (MAFOD) trial is designed to compare the haemostatic effect of DTCs versus room temperature-stored platelets (RSP) in the treatment of surgical bleeding.

Methods

The MAFOD trial is a single-blinded, randomized controlled non-inferiority trial and will be conducted in three level 1 trauma centres in The Netherlands. Patients 12 years or older, alive at hospital presentation, requiring a massive transfusion including platelets and with signed (deferred) consent will be included. The primary outcome is the percentage of patients that have achieved haemostasis within 6 h and show signs of life. Haemostasis is defined as the time in minutes from arrival to the time of the last blood component transfusion (plasma/platelets or red blood cells), followed by a 2-h transfusion-free period. This is the first randomized controlled study investigating DTCs in trauma and vascular surgical bleeding.

Discussion

The hypothesis is that the percentage of patients that will achieve haemostasis in the DTC group is at least equal to the RSP group (85%). With a power of 80%, a significance level of 5% and a non-inferiority limit of 15%, a total of 71 patients in each arm are required, thus resulting in a total of 158 patients, including a 10% refusal rate. The data collected during the study could help improve the use of platelets during resuscitation management. If proven non-inferior in civilian settings, frozen platelets may be used in the future to optimize logistics and improve platelet availability in rural or remote areas for the treatment of (massive) bleeding trauma patients in civilian settings.

Trial registration

ClinicalTrials.gov NCT05502809. Registered on 16 August 2022.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06739-2.

There and Back Again: The Once and Current Developments in Donor-Derived Platelet Products for Products for Hemostatic Therapy

Over 100 years ago, Duke transfused whole blood to a thrombocytopenic patient to raise the platelet count and prevent bleeding. Since then, platelet transfusions have undergone numerous modifications from whole blood-derived platelet-rich plasma to apheresis-derived platelet concentrates. Similarly, the storage time and temperature have changed. The mandate to store platelets for a maximum of 5-7 days at room temperature has been challenged by recent clinical trial data, ongoing difficulties with transfusion-transmitted infections, and recurring periods of shortages, further exacerbated by the COVID-19 pandemic. Alternative platelet storage approaches are as old as the first platelet transfusions. Cold-stored platelets may offer increased storage times (days) and improved hemostatic potential at the expense of reduced circulation time. Frozen (cryopreserved) platelets extend the storage time to years but require storage at -80 °C and thawing before transfusion. Lyophilized platelets can be powder-stored for years at room temperature and reconstituted within minutes in sterile water but are probably the least explored alternative platelet product to date. Finally, whole blood offers the hemostatic spectrum of all blood components but has challenges, such as ABO incompatibility. While we know more than ever before about the in vitro properties of these products, clinical trial data on these products are accumulating. The purpose of this review is to summarize the findings of recent preclinical and clinical studies on alternative, donor-derived platelet products.