Bacterial contamination of platelets for transfusion: strategies for prevention

Transfusion-transmitted infections

The risk of transfusion-transmitted infection (TTI) has always existed because transfused blood products are biological materials derived from humans. To prevent TTIs, screening strategies have been developed for various infectious diseases, such as hepatitis B virus, hepatitis C virus, and human immunodeficiency virus, contributing significantly to reducing TTI globally. Nevertheless, septic transfusion reactions (STRs) due to bacterial contamination remain an unresolved issue. Various infectious diseases can be transmitted through blood products, and preventive and selective screening strategies have been applied across different regions. Although multiple strategies, including culture-based and rapid detection kit-based methods, have been introduced to overcome STRs, complete prevention has not yet been achieved. Recently, pathogen inactivation methods have been developed to eliminate non-specific organisms rather than screening specific organisms. This approach is anticipated to contribute significantly to diminishing the risk of TTIs in the future.

Ultrasoft platelet-like particles stop bleeding in rodent and porcine models of trauma

Uncontrolled bleeding after trauma represents a substantial clinical problem. The current standard of care to treat bleeding after trauma is transfusion of blood products including platelets; however, donated platelets have a short shelf life, are in limited supply, and carry immunogenicity and contamination risks. Consequently, there is a critical need to develop hemostatic platelet alternatives. To this end, we developed synthetic platelet-like particles (PLPs), formulated by functionalizing highly deformable microgel particles composed of ultralow cross-linked poly (N-isopropylacrylamide) with fibrin-binding ligands. The fibrin-binding ligand was designed to target to wound sites, and the cross-linking of fibrin polymers was designed to enhance clot formation. The ultralow cross-linking of the microgels allows the particles to undergo large shape changes that mimic platelet shape change after activation; when coupled to fibrin-binding ligands, this shape change facilitates clot retraction, which in turn can enhance clot stability and contribute to healing. Given these features, we hypothesized that synthetic PLPs could enhance clotting in trauma models and promote healing after clotting. We first assessed PLP activity in vitro and found that PLPs selectively bound fibrin and enhanced clot formation. In murine and porcine models of traumatic injury, PLPs reduced bleeding and facilitated healing of injured tissue in both prophylactic and immediate treatment settings. We determined through biodistribution experiments that PLPs were renally cleared, possibly enabled by ultrasoft particle properties. The performance of synthetic PLPs in the preclinical studies shown here supports future translational investigation of these hemostatic therapeutics in a trauma setting.

Evaluation of bacterial safety approaches of platelet blood concentrates: bacterial screening and pathogen reduction

This mini-review analyzed two approaches to screening bacterial contamination and utilizing pathogen reduction technology (PRT) for Platelet concentrates (PCs). While the culture-based method is still considered the gold standard for detecting bacterial contamination in PCs, efforts in the past two decades to minimize transfusion-transmitted bacterial infections (TTBIs) have been insufficient to eliminate this infectious threat. PRTs have emerged as a crucial tool to enhance safety and mitigate these risks. The evidence suggests that the screening strategy for bacterial contamination is more successful in ensuring PC quality, decreasing the necessity for frequent transfusions, and improving resistance to platelet transfusion. Alternatively, the PRT approach is superior regarding PC safety. However, both methods are equally effective in managing bleeding. In conclusion, PRT can become a more prevalent means of safety for PCs compared to culture-based approaches and will soon comprehensively surpass culture-based bacterial contamination detection methods.

Verification of a method using magnetic bead enrichment and nucleic acid extraction to improve the molecular detection of bacterial contamination in blood components

Bacterial contamination of blood products poses a significant risk in transfusion medicine. Platelets are particularly vulnerable to bacterial growth because they must be stored at room temperature with constant agitation for >5 days. The limitations of bacterial detection using conventional methods, such as blood cultures and lateral flow assays, include the long detection times, low sensitivity, and the requirement for substantial volumes of blood components. To address these limitations, we assessed the performance of a bacterial enrichment technique using antibiotic-conjugated magnetic nanobeads (AcMNBs) and real-time PCR for the detection of bacterial contamination in plasma. AcMNBs successfully captured >80% of four bacterial strains, including Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Klebsiella pneumoniae, in both plasma and phosphate-buffered saline. After 24-h incubation with bacterial enrichment, S. aureus and B. cereus were each detected at 101 CFU/mL in all trials (5/5), E. coli at 101 CFU/mL in 1/5 trials, and K. pneumoniae at 10² CFU/mL in 4/5 trials. Additionally, without incubation, the improvement was also achieved in samples with bacterial enrichment, S. aureus at 10² CFU/mL and B. cereus at 101 CFU/mL in 1/5 trials each, E. coli at 10³ CFU/mL in 3/5 trials, and K. pneumoniae at 10¹ CFU/mL in 2/5 trials. Overall, the findings from this study strongly support the superiority of bacterial enrichment in detecting low-level bacterial contamination in plasma when employing AcMNBs and PCR.IMPORTANCEThe study presents a breakthrough approach to detect bacterial contamination in plasma, a critical concern in transfusion medicine. Traditional methods, such as blood cultures and lateral flow assays, are hampered by slow detection times, low sensitivity, and the need for large blood sample volumes. Our research introduces a novel technique using antibiotic-conjugated magnetic nanobeads combined with real-time PCR, enhancing the detection of bacteria in blood products, especially platelets. This method has shown exceptional efficiency in identifying even low levels of four different species of bacteria in plasma. The ability to detect bacterial contamination rapidly and accurately is vital for ensuring the safety of blood transfusions and can significantly reduce the risk of infections transmitted through blood products. This advancement is a pivotal step in improving patient outcomes and elevating the standards of care in transfusion medicine.

Fibrinogen contribution to clot strength in patients with sepsis and hematologic malignancies and thrombocytopenia-a prospective, single-center, analytical, cross-sectional study

Background

Patients with hematological malignancies (HM) frequently present thrombocytopenia and higher risk of bleeding. Although transfusion is associated with higher risk of adverse events and poor outcomes, prophylactic transfusion of platelets is a common practice to prevent hemorrhagic complications. Thromboelastometry has been considered a better predictor for bleeding than isolated platelet counts in different settings. In early stages of sepsis, hypercoagulability may occur due to higher fibrinogen levels.

Objectives

To evaluate the behavior of coagulation in patients with HM who develop sepsis and to verify whether a higher concentration of fibrinogen is associated with a proportional increase in maximum clot firmness (MCF) even in the presence of severe thrombocytopenia.

Methods

We performed a unicentric analytical cross-sectional study with 60 adult patients with HM and severe thrombocytopenia, of whom 30 had sepsis (sepsis group) and 30 had no infections (control group). Coagulation conventional tests and specific coagulation tests, including thromboelastometry, were performed. The main outcome evaluated was MCF.

Results

Higher levels of fibrinogen and MCF were found in sepsis group. Both fibrinogen and platelets contributed to MCF. The relative contribution of fibrin was significantly higher (60.5 ± 12.8% vs 43.6 ± 9.7%; P < .001) and that of platelets was significantly lower (39.5 ± 12.8% vs 56.4 ± 9.7%; P < .001) in the sepsis group compared with the control group.

Conclusion

Patients with sepsis and HM presented higher concentrations of fibrinogen than uninfected patients, resulting in greater MCF amplitudes even in the presence of thrombocytopenia.

Associated criteria used in investigating suspected septic transfusion reactions: A scoping review

BACKGROUND AND OBJECTIVES

Septic transfusion reactions (STRs) occur as a result of bacterial contamination of blood or blood products, resulting in sepsis. This scoping review aimed to identify, explore and map the available literature on the STR criteria triggering the investigation of STR.

MATERIALS AND METHODS

Four electronic databases (MEDLINE, Web of Science, Science Direct, Embase) were searched to retrieve scientific literature reporting such criteria, published from 1 January 2000 to 5 May 2022. Grey literature was also searched from open web sources.

RESULTS

Of 1052 references identified, 43 (21 peer-reviewed and 22 grey literature) met the eligibility criteria for inclusion and data extraction after full article screening. Of them, most (27/43, 62.79%) were found to report a single set of criteria, and only two reported four or more sets of criteria. The analysis of 66 sets of criteria collected from the selected references revealed 57 different sets. A few sets of criteria used only one sign and symptom (s/s) (12.12%, n = 8), whereas 16 sets used 7-15 s/s (n = 16/66; 24.24%). Of the total 319 occurrences of s/s associated with the 66 sets of criteria, post-transfusion hyperthermia, body temperature increase and hypotension were the most common s/s categories. Of all the literature available, only one study tested the diagnostic accuracy of the STR criteria.

CONCLUSION

This scoping review revealed a substantial variation in criteria used to identify suspected STR. Consequently, conducting further studies to enhance the diagnostic accuracy of these criteria, which trigger STR investigations, is imperative for advancing clinical practice.

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.

Changes in inflammatory responses and autophagy during apheresis platelet preservation and their correlation with platelet transfusion refractoriness in patients with acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a common hematopoietic malignancy, and platelet transfusion plays a crucial role in its treatment. This study aimed to investigate the changes in inflammatory response and autophagy during the preservation of apheresis platelets (AP) and their correlation with platelet transfusion refractoriness (PTR) in ALL. ALL patients were included, and APs were categorized based on the preservation period (day 0, day 1, days 2-3, and days 4-5). The activation factors procaspase-activating compound 1 (PAC-1) and P-selectin (CD62P), AP aggregation function, inflammation levels (interleukin 1 beta [IL-1β], interleukin 6 [IL-6], tumor necrosis factor alpha [TNF-α] and NOD-like receptor thermal protein domain associated protein 3 [NLRP3]), and autophagy-related genes (p62) during AP preservation were assessed. Following co-culturing APs with peripheral blood mononuclear cells (PBMCs), specific activation markers were studied to observe APs influence on immune cells activation. The effectiveness of platelet transfusion was assessed, and risk factors for PTR were analyzed. As the storage duration of AP increased, the activation factors, coagulation factor activity, inflammation levels, and the activation of immune cells in AP increased, while fibrinogen levels and AP aggregation function decreased. The expression levels of autophagy-related genes (the autophagy marker light chain 3B gene [LC3B] and Beclin 1 gene) decreased with prolongation preservation. The effective rate of AP transfusion in ALL patients was 68.21%. AP preservation time, IL-6, p62, and Beclin 1 were identified as independent risk factors affecting PTR in ALL patients. In conclusion, during AP preservation, inflammation, autophagy, and activation of immune cells were observed to increase. AP preservation time, IL-6, p62, and Beclin 1 were independent risk factors for PTR.

Listeria monocytogenes Transmission from Donated Blood to Platelet Transfusion Recipient, Italy

We report Listeria monocytogenes infection in a patient in Italy who was transfused with pooled platelet concentrate. Genomic analysis revealed that L. monocytogenes isolates from the donor blood unit, the transfused platelets, and the patient's blood culture were genetically closely related, confirming transfusion transmission. Additional surveillance and secondary bacterial screening could improve transfusion safety.

Cold-stored platelets for acute bleeding in cardiac surgical patients: a narrative review

PURPOSE

Cold-stored platelets (CSP) are an increasingly active topic of international research. They are maintained at 1-6 °C, in contrast to standard room-temperature platelets (RTP) kept at 20-24 °C. Recent evidence suggests that CSP have superior hemostatic properties compared with RTP. This narrative review explores the application of CSP in adult cardiac surgery, summarizes the preclinical and clinical evidence for their use, and highlights recent research.

SOURCE

A targeted search of MEDLINE and other databases up to 24 February 2022 was conducted. Search terms combined concepts such as cardiac surgery, blood, platelet, and cold-stored. Searches of trial registries ClinicalTrials.gov and WHO International Clinical Trials Registry Platform were included. Articles were included if they described adult surgical patients as their population of interest and an association between CSP and clinical outcomes. References of included articles were hand searched.

PRINCIPAL FINDINGS

When platelets are stored at 1-6 °C, their metabolic rate is slowed, preserving hemostatic function for increased storage duration. Cold-stored platelets have superior adhesion characteristics under physiologic shear conditions, and similar or superior aggregation responses to physiologic agonists. Cold-stored platelets undergo structural, metabolic, and molecular changes which appear to "prime" them for hemostatic activity. While preliminary, clinical evidence supports the conduct of trials comparing CSP with RTP for patients with platelet-related bleeding, such as those undergoing cardiac surgery.

CONCLUSION

Cold-stored platelets may have several advantages over RTP, including increased hemostatic capacity, extended shelf-life, and reduced risk of bacterial contamination. Large clinical trials are needed to establish their potential role in the treatment of acutely bleeding patients.

Advancing herbal medicine: enhancing product quality and safety through robust quality control practices

This manuscript provides an in-depth review of the significance of quality control in herbal medication products, focusing on its role in maintaining efficiency and safety. With a historical foundation in traditional medicine systems, herbal remedies have gained widespread popularity as natural alternatives to conventional treatments. However, the increasing demand for these products necessitates stringent quality control measures to ensure consistency and safety. This comprehensive review explores the importance of quality control methods in monitoring various aspects of herbal product development, manufacturing, and distribution. Emphasizing the need for standardized processes, the manuscript delves into the detection and prevention of contaminants, the authentication of herbal ingredients, and the adherence to regulatory standards. Additionally, it highlights the integration of traditional knowledge and modern scientific approaches in achieving optimal quality control outcomes. By emphasizing the role of quality control in herbal medicine, this manuscript contributes to promoting consumer trust, safeguarding public health, and fostering the responsible use of herbal medication products.

The impact of donor biological variation on the quality and function of cold-stored platelets

BACKGROUND AND OBJECTIVES

Room temperature-stored platelets (RTPs) maximize platelet viability but limit shelf life. The aims of this study were to investigate the impact of donor variability on cold-stored platelets (CSPs) and RTP, to determine whether RTP quality markers are appropriate for CSP.

MATERIALS AND METHODS

Double platelet donations (n = 10) were collected from consented regular male donors stored in 100% plasma. A full blood count, donor age, weight, height and body mass index (BMI) were collected at the time of donation. Platelet donations were split equally into two bags, and assigned to non-agitated CSP or agitated RTP. The quality and function of platelets were assessed throughout the standard 7 days of storage and at expiry (day 8). Non-parametric statistical analyses were used to analyse results given the small sample size.

RESULTS

As expected, there were significant differences between CSP and RTP throughout storage including a reduction in CSP concentration as well as a loss of swirling. Furthermore, a significant increase in CSP exhibiting activation and apoptotic markers was observed. Platelet concentrations were further impacted by donor BMI, and donors with the highest BMI (>29) had the lowest platelet concentration and activation response at the end of CSP storage.

CONCLUSION

Platelet quality and functionality play a vital role in transfusion outcomes; however, blood components are inherently variable. This study demonstrated, for the first time, the specific impact of donor BMI on CSP quality and function and highlights the requirement for novel quality markers for assessing CSPs.

Evaluation of bacterial growth, effects on albumin, and coagulation factors in canine fresh frozen plasma administered as continuous rate infusion exposed to room temperature for 12 hours

OBJECTIVES

To determine the risk of bacterial growth and to analyze the stability of albumin and coagulation factors in canine fresh frozen plasma (FFP) units exposed to room temperature (24°C) administered as a continuous rate infusion (CRI) for 12 hours.

DESIGN

Ex vivo study.

SETTING

University teaching hospital and pet blood bank.

ANIMALS

None.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

An FFP CRI was simulated to replicate the standard routine procedure used in dogs. Plasma samples were collected before starting the CRI (H0), after 4 hours (H4), and after 12 hours (H12). Bacterial culture of FFP was performed and albumin concentration and specific activity levels for factors V, VII, VIII, and IX were measured and compared. All plasma culture results were negative. There were no statistically significant differences at any time point in the factor VIII activity (median 105.5% [range, 75.6%-142.0%] at H0; median 107.8% [range, 75.0%-172.7%] at H4; and median 112.1% [range, 81.7%-171.0%] at H12); factor IX activity (median 119.3% [range, 89.1%-175.9%] at H0; median 123.1% [range, 72.5%-172.7%] at H4; and median 118.3% [range, 86.6%-177.5%] at H12); or albumin concentration (median 21.0 g/L [range, 17.0-23.0 g/L] at H0 and median 20.0 g/L [range, 17.0-24.0 g/L] at H12). A slight but significant increase in factor V activity was observed when comparing H0 (median 107.0% [range, 71.0%-159.0%]) to H4 (median 117.7% [range, 71.0%-176.7%]) (P = 0.002) or H12 (median 116.2% [range, 71.0%-191.6%]) (P = 0.001). A slight but significant increase in factor VII activity was observed when comparing H0 (median 115.4% [range, 70.6%-183.7%]) to H4 (median 118.2% [range, 82.7%-194.6%]) (P = 0.005); H0 to H12 (median 128.7% [range, 86.4%-200.0%]) (P < 0.001); and H4 to H12 (P = 0.002).

CONCLUSIONS

FFP CRI at room temperature for 12 hours could be considered safe with regard to risk for bacterial growth and also effective by providing albumin and clotting factors.

Increased frequency of false-positive bacterial detection after implementation of new guidelines for large-volume delayed sampling of platelets

BACKGROUND

The updated guidance for improving bacterial detection (BD) of platelets has included the implementation of large-volume delayed sampling (LVDS) with the addition of anaerobic culture bottles (BPNs) and sampling of each platelet split product.

METHODS

The frequency of BD was reviewed during this LVDS time period in comparison with pre-LVDS and the Post-Approval Surveillance Study of Platelet Outcomes, Release Tested (PASSPORT) study (when BPNs were last used).

RESULTS

There was more than a twofold increase in bottles inoculated per collection during LVDS, with an almost fivefold increase in sample volume collected. During LVDS, the concordance of split products within an initial reactive collection was only 8.7%. There was no difference in LVDS aerobic culture bottle (BPA) true positives (TPs), but there was a significant increase in LVDS false positives (FPs), p < .0001, compared to both PASSPORT and pre-LVDS, respectively. There was an increase in BPN TPs during LVDS (p < .05 compared to PASSPORT), with predominance of Cutibacter acnes (C. acnes), noted exclusively in BPN, and accounting for more than two-fifths of all organisms detected. Time to alarm during LVDS for TPs had two peaks with one due to C. acnes at 96 h compared to 17 h for non-C. acnes.

DISCUSSION

The high FP frequency, along with low clinical significance of TPs found in BPNs, has led to the needless discard of inventory, as the utility of BPNs in BD for platelets is yet to be established and may require much larger studies.

Establishment of a stable proficiency testing matrix in transfusion microbiology in South Africa

Background

All medical laboratories must participate in proficiency testing (PT) programmes to ensure high-quality results. Proficiency testing samples mimic clinical samples; however, PT programmes for detection of bacteria in blood products are not routinely performed due to unavailability of matrix-equivalent samples.

Objective

The aim of this study was to develop and test a matrix-equivalent PT programme using blood products as the basis matrix.

Methods

A prospective cross-sectional study was conducted from April 2021 until June 2021, using 52 blood products comprising 36 pooled platelet and 16 red blood cell products at the South African National Blood Service PT laboratory in Gauteng. Products were manipulated into matrix-equivalent PT samples by spiking 42 products with known bacterial strains at specific concentrations and treating the remaining 10 products with preserving fluid containing antibiotics. The level of agreement between the researcher results and participating laboratories' results was assessed.

Results

Of the prepared matrices, 568 out of 572 (99%) were stable for 30 days. Bacteria could correctly be identified in spiked samples for up to 23 days. Samples treated with preserving fluid remained negative until day 30. For spiked samples, an average of 98% agreement (153/156) was achieved between the three participating laboratories when compared with the researcher's results; 100% agreement was achieved for unspiked samples. The kappa scores obtained from all tested variables presented with scores between 0.856 and 1.000, and the p-value was < 0.001 throughout.

Conclusion

The developed PT matrix was therefore stable and suitable to be implemented in transfusion microbiology.

What this study adds

This study demonstrated that a stable microbiology PT programme using platelets and red blood cells can be developed for use on bacterial detection analysers and could help to close the gap presented by unavailability of a blood PT matrix for transfusion microbiology.

Health Economic Aspects of Platelet Concentrates: Comparing Cost and Reimbursement of Pathogen Inactivated and Conventional Platelet Concentrates in a German Comprehensive Cancer Center

INTRODUCTION

Pathogen inactivation (PI) utilizing amotosalen and UVA light (INTERCEPT® Blood System) is a well-established method for the production of safer platelet concentrates (PCs). While many studies describe clinical and logistical benefits of PI, the implications and potential challenges from a hospital management perspective have not yet been analyzed - health economic analyses considering reimbursement of PI are lacking. The objective of this analysis was to examine the real-life inpatient treatment costs from a hospital perspective and to assess the economic impact of PI-PC versus conventional PC (CONV-PC) administration in Germany.

METHODS

Real-life cost data for inpatient cancer cases from 2020 of the University Hospital Cologne were identified by operating and procedure codes. The German diagnosis-related groups, extra fees, case mix index (CMI), length of stay (LOS), and average resource consumption of PC were evaluated from a micro-management perspective. The potential economic impact of implementing PI-treated PCs was modeled retrospectively.

RESULTS

In total, 951 inpatient cases were analyzed (CMI [median 4.7-9.9], LOS [median 26 days], number of cases in intensive care units [38%]). The median DRG fee was between EUR 13,800 and EUR 26,400. According to our model, the use of PI-PC compared to CONV-PC would result in savings between EUR 184 and EUR 306 per case.

CONCLUSION

From a hospital management perspective, oncological cases requiring PC transfusion are associated with a high CMI (reimbursement per DRG flat fee) and moderate costs with sufficient add-on payment for PI on a case level. Investment and process costs for PI implementation can be analyzed for site-specific scenarios.

One-step immunoassay based on filtration for detection of food poisoning-related bacteria

A one-step immunoassay based on filtration was presented, which used microbeads for target analyte detection and filters with appropriate pore sizes to distinguish the complexity of target analyte and microbeads. For effective bacterial detection, the microbead size and the filter's pore size must be optimized. The optimal concentrations of the enzyme (urease) and antibody were determined at the maximum absorbance change, that is, the maximum pH change. The pH change was measured using a field-effect transistor (FET). The correlation between pH change and threshold voltage was estimated to be 21.7 mV/pH, and the correlation between pH change and the source-drain current was estimated to be -379 nA/pH. For the one-step immunoassay, antibodies against target bacteria were isolated from horse serum by filtration, and these antibodies were estimated to have a sufficiently high specificity to overcome cross-reactivity among five types of food poisoning-related bacteria: Escherichia coli O157, Salmonella typhimurium, Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus. Finally, the FET-based one-step immunoassay was demonstrated for five types of food poisoning-related bacteria in human serum.

RND Pump-Mediated Efflux of Amotosalen, a Compound Used in Pathogen Inactivation Technology to Enhance Safety of Blood Transfusion Products, May Compromise Its Gram-Negative Anti-Bacterial Activity

Pathogen inactivation is a strategy to improve the safety of transfusion products. The only pathogen reduction technology for blood products currently approved in the US utilizes a psoralen compound, called amotosalen, in combination with UVA light to inactivate bacteria, viruses, and protozoa. Psoralens have structural similarity to bacterial multidrug efflux pump substrates. As these efflux pumps are often overexpressed in multidrug-resistant pathogens, we tested whether contemporary drug-resistant pathogens might show resistance to amotosalen and other psoralens based on multidrug efflux mechanisms through genetic, biophysical, and molecular modeling analysis. The main efflux systems in Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa are tripartite resistance-nodulation-cell division (RND) systems, which span the inner and outer membranes of Gram-negative pathogens, and expel antibiotics from the bacterial cytoplasm into the extracellular space. We provide evidence that amotosalen is an efflux substrate for the E. coli AcrAB, Acinetobacter baumannii AdeABC, and P. aeruginosa MexXY RND efflux pumps. Furthermore, we show that the MICs for contemporary Gram-negative bacterial isolates for these species and others in vitro approached and exceeded the concentration of amotosalen used in the approved platelet and plasma inactivation procedures. These findings suggest that otherwise safe and effective inactivation methods should be further studied to identify possible gaps in their ability to inactivate contemporary, multidrug-resistant bacterial pathogens. IMPORTANCE Pathogen inactivation is a strategy to enhance the safety of transfused blood products. We identify the compound, amotosalen, widely used for pathogen inactivation, as a bacterial multidrug efflux substrate. Specifically, experiments suggest that amotosalen is pumped out of bacteria by major efflux pumps in E. coli, Acinetobacter baumannii, and Pseudomonas aeruginosa. Such efflux pumps are often overexpressed in multidrug-resistant pathogens. Importantly, the MICs for contemporary multidrug-resistant Enterobacterales, Acinetobacter baumannii, Pseudomonas aeruginosa, Burkholderia spp., and Stenotrophomonas maltophilia isolates approached or exceeded the amotosalen concentration used in approved platelet and plasma inactivation procedures, potentially as a result of efflux pump activity. Although there are important differences in methodology between our experiments and blood product pathogen inactivation, these findings suggest that otherwise safe and effective inactivation methods should be further studied to identify possible gaps in their ability to inactivate contemporary, multidrug-resistant bacterial pathogens.

Implementation of helicase-dependent amplification with SYBR Green I for prompt naked-eye detection of bacterial contaminants in platelet products

Platelet transfusions may lead to more significant risks of infection and septic transfusion reactions that can be fatal to the recipient. Platelet products should be screened to limit or detect bacterial contamination before application to patients to minimise any adverse reactions. This study aimed to develop a helicase-dependent amplification (HDA) technique targeting a universal highly conserved bacterial gene, 16S rRNA, in combination with naked-eye detection using SYBR Green I (HDA/SYBR Green I) to detect bacterial contamination in platelet products. Thirty positive samples were obtained from spiked platelet products by five transfusion-relevant bacterial strains and were screened for bacterial contamination by HDA/SYBR Green I. HDA/SYBR Green I showed an enhanced yield of bacterial contaminant detection when performed with medium to late shelf life, Day 2 of storage or later platelet products (98.67% sensitivity and 100% specificity compared to the BACT/ALERT culture system). The limit of detection of HDA/SYBR Green I was 1 ng, and there was no cross-reaction with other organisms that could likely contaminate platelet products. The developed HDA/SYBR Green I assay is rapid and simplistic and only requires an easy-to-find heat box, available in general blood bank laboratories, for the amplification step. This technique is suitable for further development as an alternative method to detect bacterial contamination in platelet products in the near future.

Platelet transfusion in adults: An update

Many patients worldwide receive platelet components (PCs) through the transfusion of diverse types of blood components. PC transfusions are essential for the treatment of central thrombocytopenia of diverse causes, and such treatment is beneficial in patients at risk of severe bleeding. PC transfusions account for almost 10% of all the blood components supplied by blood services, but they are associated with about 3.25 times as many severe reactions (attributable to transfusion) than red blood cell transfusions after stringent in-process leukoreduction to less than 10⁶ residual cells per blood component. PCs are not homogeneous, due to the considerable differences between donors. Furthermore, the modes of PC collection and preparation, the safety precautions taken to limit either the most common (allergic-type reactions and febrile non-hemolytic reactions) or the most severe (bacterial contamination, pulmonary lesions) adverse reactions, and storage and conservation methods can all result in so-called PC "storage lesions". Some storage lesions affect PC quality, with implications for patient outcome. Good transfusion practices should result in higher levels of platelet recovery and efficacy, and lower complication rates. These practices include a matching of tissue ABH antigens whenever possible, and of platelet HLA (and, to a lesser extent, HPA) antigens in immunization situations. This review provides an overview of all the available information relating to platelet transfusion, from donor and donation to bedside transfusion, and considers the impact of the measures applied to increase transfusion efficacy while improving safety and preventing transfusion inefficacy and refractoriness. It also considers alternatives to platelet component (PC) transfusion.

Novel chemical-structure TPOR agonist, TMEA, promotes megakaryocytes differentiation and thrombopoiesis via mTOR and ERK signalings

BACKGROUND

Non-peptide thrombopoietin receptor (TPOR) agonists are promising therapies for the mitigation and treatment of thrombocytopenia. However, only few agents are available as safe and effective for stimulating platelet production for thrombocytopenic patients in the clinic.

PURPOSE

This study aimed to develop a novel small molecule TPOR agonist and investigate its underlying regulation of function in megakaryocytes (MKs) differentiation and thrombopoiesis.

METHODS

A potential active compound that promotes MKs differentiation and thrombopoiesis was obtained by machine learning (ML). Meanwhile, the effect was verified in zebrafish model, HEL and Meg-01 cells. Next, the key regulatory target was identified by Drug Affinity Responsive Target Stabilization Assay (DARTS), Cellular Thermal Shift Assay (CETSA), and molecular simulation experiments. After that, RNA-sequencing (RNA-seq) was used to further confirm the associated pathways and evaluate the gene expression induced during MK differentiation. In vivo, irradiation (IR) mice, C57BL/6N-TPOR^em1cyagen (Tpor^-/-) mice were constructed by CRISPR/Cas9 technology to examine the therapeutic effect of TMEA on thrombocytopenia.

RESULTS

A natural chemical-structure small molecule TMEA was predicted to be a potential active compound based on ML. Obvious phenotypes of MKs differentiation were observed by TMEA induction in zebrafish model and TMEA could increase co-expression of CD41/CD42b, DNA content, and promote polyploidization and maturation of MKs in HEL and Meg-01 cells. Mechanically, TMEA could bind with TPOR protein and further regulate the PI3K/AKT/mTOR/P70S6K and MEK/ERK signal pathways. In vivo, TMEA evidently promoted platelet regeneration in mice with radiation-induced thrombocytopenia but had no effect on Tpor^-/- and C57BL/6 (WT) mice.

CONCLUSION

TMEA could serve as a novel TPOR agonist to promote MKs differentiation and thrombopoiesis via mTOR and ERK signaling and could potentially be created as a promising new drug to treat thrombocytopenia.

Systematic reviews on platelet transfusions: Is there unnecessary duplication of effort? A scoping review

BACKGROUND AND OBJECTIVES

Platelet transfusions are used across multiple patient populations to prevent and correct bleeding. This scoping review aimed to map the currently available systematic reviews (SRs) and evidence-based guidelines in the field of platelet transfusion.

MATERIALS AND METHODS

A systematic literature search was conducted in seven databases for SRs on effectiveness (including dose and timing, transfusion trigger and ratio to other blood products), production modalities and decision support related to platelet transfusion. The following data were charted: methodological features of the SR, population, concept and context features, outcomes reported, study design and number of studies included. Results were synthesized in interactive evidence maps.

RESULTS

We identified 110 SRs. The majority focused on clinical effectiveness, including prophylactic or therapeutic transfusions compared to no platelet transfusion (34 SRs), prophylactic compared to therapeutic-only transfusion (8 SRs), dose, timing (11 SRs) and threshold for platelet transfusion (15 SRs) and the ratio of platelet transfusion to other blood products in massive transfusion (14 SRs). Furthermore, we included 34 SRs on decision support, of which 26 evaluated viscoelastic testing. Finally, we identified 22 SRs on platelet production modalities, including derivation (4 SRs), pathogen inactivation (6 SRs), leucodepletion (4 SRs) and ABO/human leucocyte antigen matching (5 SRs). The SRs were mapped according to concept and clinical context.

CONCLUSION

An interactive evidence map of SRs and evidence-based guidelines in the field of platelet transfusion has been developed and identified multiple reviews. This work serves as a tool for researchers looking for evidence gaps, thereby both supporting research and avoiding unnecessary duplication.

Implementation strategy for complete pathogen reduction technology treated apheresis platelet inventory

BACKGROUND

Bacterial contamination in platelets remain a major public health concern, which prompted the US Food and Drug Administration guidance for bacterial contamination mitigation. Pathogen reduction technology (PRT) is one mitigation strategy that has shown success in Europe over the last decade. Therefore, our center sought to transition from a dual system of bacterial culturing (BacT) and PRT to full PRT.

METHODS

A 1 month pilot study was conducted to simulate 100% PRT conditions. Our center also collected baseline data on key platelet production metrics in the 4 months prior to 100% PRT and compared it to the 4 months post-implementation.

RESULTS

The pilot study showed no statistical differences in split rate, proportion of low-yield products, or proportion of single, double, and triple collections. The only observed difference was an 11 min increase in the average duration of double collections. Our baseline versus post-implementation monitoring showed no difference in split rate, discard rate, percentage of low-yield units, and average yield of low yield units. Statistical differences were detected in the proportion of single, double, and triple collections, as well as the average yield of full dose products. Roughly 20% of our inventory consisted of low-yield products.

DISCUSSION

With suitable mitigation strategies, transitioning to a full PRT inventory may result in higher net margins while not adversely affecting overall platelet production. A pilot study is a good way to project potential effects of switching from a dual BacT and PRT inventory to full PRT, and can be adopted by other centers aiming to make the transition.

Adverse transfusion reactions and what we can do

INTRODUCTION

Transfusions of blood and blood components have inherent risks and the ensuing adverse reactions. It is very important to understand the adverse reactions of blood transfusion comprehensively for ensuring the safety of any future transfusions.

AREAS COVERED

According to the time of onset, adverse reactions of blood transfusion are divided into immediate and delayed transfusion reactions. In acute transfusion reactions, timely identification and immediate cessation of transfusion is critical. Vigilance is required to distinguish delayed responses or reactions that present non-specific signs and symptoms. In this review, we present the progress of mechanism, clinical characteristics and management of commonly encountered transfusion reactions.

EXPERT OPINION

The incidence of many transfusion-related adverse events is decreasing, but threats to transfusion safety are always emerging. It is particularly important for clinicians and blood transfusion staff to recognize the causes, symptoms and treatment methods of adverse blood transfusion reactions to improve the safety. In the future, at-risk patients will be better identified and can benefit from more closely matched blood components.

Augmented Production of Platelets From Cord Blood With Euchromatic Histone Lysine Methyltransferase Inhibition

Cord blood hematopoietic stem/progenitor cells (CB-HSPCs) have emerged as a promising supply for functional platelets to potentially alleviate the increasing demand for platelet transfusions, but the clinical application has been limited by the undefined molecular mechanism and insufficient platelet production. Here, we performed single-cell profiling of more than 16 160 cells to construct a dynamic molecular landscape of human megakaryopoiesis from CB-HSPCs, enabling us to uncover, for the first time, cellular heterogeneity and unique features of neonatal megakaryocytes (MKs) and to also offer unique resources for the scientific community. By using this model, we defined the genetic programs underlying the differentiation process from megakaryocyte-erythroid progenitors (MEPs) to MKs via megakaryocyte progenitors (MKPs) and identified inhibitors of euchromatic histone lysine methyltransferase (EHMT), which, when applied at the early stage of differentiation, significantly increase the final platelet production. At the mechanistic level, we found that EHMT inhibitors act to selectively induce the expansion of MEPs and MKPs. Together, we uncover new mechanistic insights into human megakaryopoiesis and provide a novel chemical strategy for future large-scale generation and clinical applications of platelets.

FluidFM-Based Fabrication of Nanopatterns: Promising Surfaces for Platelet Storage Application

Platelets are cell fragments from megakaryocytes devoid of the cell nucleus. They are highly sensitive and easily activated by nonphysiological surfaces. Activated platelets have an intrinsic mechanism to release various proteins that participate in multiple pathways, initiating the platelet activation cascade. Surface-induced platelet activation is a challenge encountered during platelet storage, which eventually leads to aggregation of platelets and can thereby result in the degradation of the platelet concentrates. We have previously reported that surface-induced platelet activation can be minimized by either modifying their contact surfaces with polymers or introducing nanogroove patterns underneath the platelets. Here, we investigated the response of platelets to various nanotopographical surfaces printed using fluidic force microscopy (FluidFM). We found that the hemispherical array (grid) and hexagonal tile (hive) structures caused a reduction of surface stiffness, which leads to an inhibition of platelet adhesion. Our results reveal that nanopatterns enable the inhibition of platelet activation on surfaces, thus implying that development in nanotexturing of storage bags can extend the lifetime of platelet concentrates.

Blood Transfusion Reactions-A Comprehensive Review of the Literature including a Swiss Perspective

Blood transfusions have been the cornerstone of life support since the introduction of the ABO classification in the 20th century. The physiologic goal is to restore adequate tissue oxygenation when the demand exceeds the offer. Although it can be a life-saving therapy, blood transfusions can lead to serious adverse effects, and it is essential that physicians remain up to date with the current literature and are aware of the pathophysiology, initial management and risks of each type of transfusion reaction. We aim to provide a structured overview of the pathophysiology, clinical presentation, diagnostic approach and management of acute transfusion reactions based on the literature available in 2022. The numbers of blood transfusions, transfusion reactions and the reporting rate of transfusion reactions differ between countries in Europe. The most frequent transfusion reactions in 2020 were alloimmunizations, febrile non-hemolytic transfusion reactions and allergic transfusion reactions. Transfusion-related acute lung injury, transfusion-associated circulatory overload and septic transfusion reactions were less frequent. Furthermore, the COVID-19 pandemic has challenged the healthcare system with decreasing blood donations and blood supplies, as well as rising concerns within the medical community but also in patients about blood safety and transfusion reactions in COVID-19 patients. The best way to prevent transfusion reactions is to avoid unnecessary blood transfusions and maintain a transfusion-restrictive strategy. Any symptom occurring within 24 h of a blood transfusion should be considered a transfusion reaction and referred to the hemovigilance reporting system. The initial management of blood transfusion reactions requires early identification, immediate interruption of the transfusion, early consultation of the hematologic and ICU departments and fluid resuscitation.

Controlling Infectious Risk in Transfusion: Assessing the Effectiveness of Skin Disinfection in Blood Donors

Bacterial infectious risk is a major problem in transfusion medicine. The type of micro-organisms isolated during bacterial contamination of blood products indicates that the donor’s skin is its main source. In this context, the primary measures to reduce this risk are: (a) optimal disinfection of the donor’s arm and (b) satellite bag diversion of the initial volume of blood collected. This work aimed to verify the effectiveness of skin disinfection of the blood donor’s venipuncture site. Two methodological approaches were used: (a) qualitative and quantitative microbiological testing of the skin at the collection site, before and post-disinfection; (b) qualitative microbiological testing of the first deviated blood. Pre-disinfection testing showed skin microbial load values between 3 and >200 CFU/plate. More than two-thirds of the isolates were Gram-positive bacteria (77.8%) of which 57.7% were staphylococci. Among Gram-negative bacteria, Pseudomonadaceae, Enterobacteriaceae, and Acinetobacter spp. were isolated from the blood donors (BDs). Post-disinfection, a 100% reduction in microbial load was observed in 84.4% of BDs. Microbiological testing of the first blood diverted sample revealed the presence of microbial flora in 1.9% samples; of the isolates, 83.3% were non-aureus staphylococci. This study highlights the importance of the correct application of skin disinfection procedures in order to ensure blood safety.

Evaluation and management of platelet transfusion refractoriness

Platelet transfusion refractoriness (PTR), in which platelet counts do not increase after transfusion, occurs in many patients receiving platelet transfusions. PTR is a clinical condition that can harm patients. The causes of PTR can be divided into two types: immune and non-immune. Most cases of PTR are non-immune. Among immune causes, the most common is human leukocyte antigen (HLA) class I molecules. PTR caused by anti-HLA antibodies is usually managed by transfusing HLA-matched platelets. Therefore, it is important, especially for hemato-oncologists who frequently perform transfusion, to accurately diagnose whether the cause of platelet transfusion failure is alloimmune or non-immunological when determining the treatment direction for the patient. In this review, we discuss the definitions, causes, countermeasures, and prevention methods of PTR.

Current status of rapid bacterial detection methods for platelet components: A 20-year review by the ISBT Transfusion-Transmitted Infectious Diseases Working Party Subgroup on Bacteria

BACKGROUND AND OBJECTIVES

Bacterial contamination of platelet components (PCs) poses a safety challenge for transfusion patients. Despite mitigation interventions, the residual risk of transfusion-transmitted bacterial infections remains predominant. PC safety can be improved either by pathogen reduction or by implementation of bacterial detection methods. Detection methodologies include culture methods and rapid detection methods. The current review focuses on currently available rapid detection methods.

MATERIALS AND METHODS

We reviewed published manuscripts since 2000 on rapid bacterial detection methods used for PC screening with result determination within 4 h. Methods meeting this criterion included Verax PGDprime, BacTx and nucleic amplification testing. The analytical and diagnostic sensitivity and specificity of these systems were assessed.

RESULTS

The analytical sensitivity between the different detection methods ranged between 50 and 100,000 CFU/ml. The sample volume used by these testing systems varies between 0.5 and 1.0 ml of PCs. A delay of at least 48 h before sampling enhances detectability. All rapid detection methods generate results in a timely manner, allowing testing to be performed before transfusion with optimal sensitivity.

CONCLUSION

Rapid detection methods improve PC safety regarding bacterial contamination. The assays are optimal for rapidly growing bacteria, which are more likely to cause septic transfusion reactions in patients. Because of the reduced diagnostic sensitivity, the sample collection should be late in shelf-life and ideally just before transfusion. The major benefit of these methods is that the test result can be obtained before releasing PCs for transfusion or to be used in combination with other screening methods applied early during PC storage.

Application of Standardized Residual Component Culture Criteria for Suspected Septic Transfusion Reactions Would Increase the Component Culturing Rate at a Single Academic Medical Center

OBJECTIVES

The 2019 SCARED study developed the Biomedical Excellence for Safer Transfusion (BEST) criteria in an effort to standardize the decision to culture residual units in the context of suspected septic transfusion reactions (STRs). The goal of this study was to apply the BEST criteria to determine the effect on the transfusion reaction decision to culture.

METHODS

This retrospective, single-center, cross-sectional study assessed adult transfusion reactions identified in calendar years 2013 to 2020. Reactions following transfusion of RBCs, platelets, and plasma were included, and the decisions to culture following strict application of BEST criteria were compared with decisions to culture in actual practice.

RESULTS

In total, 1,068 transfusion reactions were reported and 200 (19%) suspected STRs were cultured, all with negative results; 303 (28%) reactions would have been cultured per strict application of the BEST criteria. Concordance between actual culture decision and BEST criteria recommendation was 62% for cultured components and 79% for components that were not cultured.

CONCLUSIONS

BEST criteria provide objective recommendations of when to culture residual units implicated in suspected STRs, but strict application of these criteria may result in increased culture rates. Clinical correlation to aid in the decision to culture is recommended.

Protein Concentrations in Stored Pooled Platelet Concentrates Treated with Pathogen Inactivation by Amotosalen Plus Ultraviolet a Illumination

Platelet granules contain a diverse group of proteins. Upon activation and during storage, platelets release a number of proteins into the circulation or supernatant of stored platelet concentrate (PC). The aim of this work was to investigate the effect of pathogen inactivation (PI) on a selection of proteins released in stored platelets. Materials and Methods: PCs in platelet additive solution (PAS) were produced from whole blood donations using the buffy coat (BC) method. PCs in the treatment arm were pathogen inactivated with amotosalen and UVA, while PCs in the second arm were used as an untreated platelet control. Concentrations of 36 proteins were monitored in the PCs during storage. Results: The majority of proteins increased in concentration over the storage period. In addition, 10 of the 29 proteins that showed change had significantly different concentrations between the PI treatment and the control at one or more timepoints. A subset of six proteins displayed a PI-related drop in concentration. Conclusions: PI has limited effect on protein concentration stored PC supernatant. The protein’s changes related to PI treatment with elevated concentration implicate accelerated Platelet storage lesion (PSL); in contrast, there are potential novel benefits to PI related decrease in protein concentration that need further investigation.

Freeze-dried platelets are a promising alternative in bleeding thrombocytopenic patients with hematological malignancies

Thrombosomes are trehalose-stabilized, freeze-dried group O platelets with a 3-year shelf life. They can be stockpiled, rapidly reconstituted, and infused regardless of the recipient's blood type. Thrombosomes thus represent a potential alternative platelet transfusion strategy. The present study assessed the safety and potential early signals of efficacy of Thrombosomes in bleeding thrombocytopenic patients. We performed an open-label, phase 1 study of single doses of allogeneic Thrombosomes at three dose levels in three cohorts, each consisting of eight patients who had hematologic malignancies, thrombocytopenia, and bleeding. Adverse events, dose-limiting toxicities (DLTs), World Health Organization (WHO) bleeding scores, and hematology values were assessed. No DLTs were reported. The median age was 59 years (24-71). Most patients had AML (58%) or ALL (29%), followed by MDS (8%) and myeloproliferative neoplasm (4%). The WHO scores of 22 patients who were actively bleeding at a total of 27 sites at baseline either improved (n = 17 [63%]) or stabilized (n = 10 [37%]) through day 6. Twenty-four hours after infusion, 12 patients (50%) had a clinically significant platelet count increase. Of eight patients who received no platelet transfusions for 6 days after Thrombosomes infusion, 5 had a clinically significant increase in platelet count of ≥5000 platelets/μL and 2 had platelet count normalization. Thrombosomes doses up to 3.78 × 10⁸ particles/kg demonstrated safety in 24 bleeding, thrombocytopenic patients with hematological malignancies. Thrombosomes may represent an alternative to conventional platelets to treat bleeding. A phase 2 clinical trial in a similar patient population is underway.

The international experience of bacterial screen testing of platelet components with automated microbial detection systems: An update

In 2014, the bacterial subgroup of the Transfusion-Transmitted Infectious Diseases working party of ISBT published a review on the International Experience of Bacterial Screen Testing of Platelet Components (PCs) with an Automated Microbial Detection System. The purpose of this review, which is focused on publications on or after 2014, is to summarize recent experiences related to bacterial contamination of PCs and the use of an automated culture method to safeguard the blood supply. We first reviewed septic transfusion reactions after PC transfusion as reported in national haemovigilance systems along with a few reports from various countries on bacterial contamination of blood products. Next, we reviewed PC automated culture protocols employed by national blood services in the United Kingdom, Australia, Canada and large blood collection organization and hospital transfusion services in the United States. Then, we acknowledged the limitations of currently available culture methodologies in abating the risks of transfusion-transmitted bacterial infection, through a review of case reports. This review was neither meant to be critical of the literature reviewed nor meant to identify or recommend a best practice. We concluded that significant risk reduction can be achieved by one or a combination of more than one strategy. No one approach is feasible for all institutions worldwide. In selecting strategies, institutions should consider the possible impact on platelet components availability and entertain a risk-based decision-making approach that accounts for operational, logistical and financial factors.

Expanded validation of the effect and quality of a pathogen inactivation system based on riboflavin photochemistry on platelet bacterial contamination

Background

Bacterial contamination still poses serious challenges to blood safety. Platelets have the highest bacterial contamination risk of all blood components.

Methods

Twenty units of manual platelets were prepared from blood donated by our hospital, which were inoculated with Staphylococcus aureus and Escherichia coli suspensions. The riboflavin sodium phosphate solution was added into platelets, adjusted to a final concentration of 160 μmol/L. Platelets added into an illumination bag and placed in the inactivation system for riboflavin photochemistry at various doses. The inactivation effect of bacteria was evaluated on a Columbia blood agar plate by the plate counting method. Meanwhile, the blood routine, blood gas analysis, platelet aggregation test, and thromboelastogram of platelets before and after treatment were detected to evaluate the changes of platelet quality after treatment.

Results

the inactivation effect of S. aureus and E. coli at the inactivation dose (16.9 J/cm²) could reach more than 4 logs. After treatment at 16.9 J/cm², the blood routine results showed that the platelet count was significantly different (P<0.05), and the blood gas analysis showed that the oxygen partial pressure (pO₂) and lactic acid concentration (cLac) were also significantly different (P<0.05). After 16.9 J/cm² treatment, there was a significant difference between Arachidonic acid (AA) and Collagen (Cog) activator groups in the platelet aggregation experiment (P<0.05), but there was no significant difference in the main thrombelastogram (TEG) parameters (R value, K value, angle value, MA value) after treatment (P>0.05).

Conclusions

The inactivation effect of this set of blood component pathogen inactivation system on platelet bacterial contamination could be considered to meet actual clinical needs, with the inactivation treatment having little impact on platelet function.

Bacterial safety study of the production process of hemoglobin-based oxygen carriers

Hemoglobin microparticles (HbMP) produced with a three-step procedure, including coprecipitation of hemoglobin with manganese carbonate, protein cross-linking, and dissolution of the carbonate template were shown to be suitable for application as artificial oxygen carriers. First preclinical safety investigations delivered promising results. Bacterial safety plays a decisive role during the production of HbMP. Therefore, the bioburden and endotoxin content of the starting materials (especially hemoglobin) and the final particle suspension are intensively tested. However, some bacteria may not be detected by standard tests due to low concentration. The aim of this study was to investigate how these bacteria would behave in the fabrication process. Biocidal effects are known for glutaraldehyde and for ethylenediaminetetraacetic acid, chemicals that are used in the fabrication process of HbMP. It was shown that both chemicals prevent bacterial growth at the concentrations used during HbMP fabrication. In addition, the particle production was carried out with hemoglobin solutions spiked with Escherichia coli or Staphylococcus epidermidis. No living bacteria could be detected in the final particle suspensions. Therefore, we conclude that the HbMP fabrication procedure is safe in respect of bacterial contamination.

Study protocol of associated criteria used in investigating septic transfusion reactions (STRs): A scoping review about available evidence

Background and objective

Assessment criteria for septic transfusion reactions (STRs) are variable around the world. A scoping review will be carried out to find out, explore and map existing literature on STRs associated criteria.

Methods

This scoping review will include indexed and grey literatures available in English or French language from January 1, 2000, to December 31, 2021. Literature search will be conducted using four electronic databases (i.e., MEDLINE via PubMed, Web of Science, Science Direct, and Embase via Ovid), and grey literatures accompanying the research questions and objectives. Based on the inclusion criteria, studies will be independently screened by two reviewers for title, abstract, and full text. Extracted data will be presented in tabular form followed by a narrative description of inputs corresponding to research objectives and questions.

Characterization of the Antibacterial Activity of an SiO2 Nanoparticular Coating to Prevent Bacterial Contamination in Blood Products

Technological innovations and quality control processes within blood supply organizations have significantly improved blood safety for both donors and recipients. Nevertheless, the risk of transfusion-transmitted infection remains non-negligible. Applying a nanoparticular, antibacterial coating at the surface of medical devices is a promising strategy to prevent the spread of infections. In this study, we characterized the antibacterial activity of an SiO₂ nanoparticular coating (i.e., the “Medical Antibacterial and Antiadhesive Coating” [MAAC]) applied on relevant polymeric materials (PM) used in the biomedical field. Electron microscopy revealed a smoother surface for the MAAC-treated PM compared to the reference, suggesting antiadhesive properties. The antibacterial activity was tested against selected Gram-positive and Gram-negative bacteria in accordance with ISO 22196. Bacterial growth was significantly reduced for the MAAC-treated PVC, plasticized PVC, polyurethane and silicone (90–99.999%) in which antibacterial activity of ≥1 log reduction was reached for all bacterial strains tested. Cytotoxicity was evaluated following ISO 10993-5 guidelines and L929 cell viability was calculated at ≥90% in the presence of MAAC. This study demonstrates that the MAAC could prevent bacterial contamination as demonstrated by the ISO 22196 tests, while further work needs to be done to improve the coating processability and effectiveness of more complex matrices.

Bioinspired artificial platelets: past, present and future

Platelets are anucleate blood cells produced from megakaryocytes predominantly in the bone marrow and released into blood circulation at a healthy count of 150,000-400,00 per μL and circulation lifespan of 7-9 days. Platelets are the first responders at the site of vascular injury and bleeding, and participate in clot formation via injury site-specific primary mechanisms of adhesion, activation and aggregation to form a platelet plug, as well as secondary mechanisms of augmenting coagulation via thrombin amplification and fibrin generation. Platelets also secrete various granule contents that enhance these mechanisms for clot growth and stability. The resultant clot seals the injury site to stanch bleeding, a process termed as hemostasis. Due to this critical role, a reduction in platelet count or dysregulation in platelet function is associated with bleeding risks and hemorrhagic complications. These scenarios are often treated by prophylactic or emergency transfusion of platelets. However, platelet transfusions face significant challenges due to limited donor availability, difficult portability and storage, high bacterial contamination risks, and very short shelf life (~5-7 days). These are currently being addressed by a robust volume of research involving reduced temperature storage and pathogen reduction processes on donor platelets to improve shelf-life and reduce contamination, as well as bioreactor-based approaches to generate donor-independent platelets from stem cells in vitro. In parallel, a complementary research field has emerged that involves the design of artificial platelets utilizing biosynthetic particle constructs that functionally emulate various hemostatic mechanisms of platelets. Here, we provide a comprehensive review of the history and the current state-of-the-art artificial platelet approaches, along with discussing the translational opportunities and challenges.

The Pathophysiology and Management of Hemorrhagic Shock in the Polytrauma Patient

The recognition and management of life-threatening hemorrhage in the polytrauma patient poses several challenges to prehospital rescue personnel and hospital providers. First, identification of acute blood loss and the magnitude of lost volume after torso injury may not be readily apparent in the field. Because of the expression of highly effective physiological mechanisms that compensate for a sudden decrease in circulatory volume, a polytrauma patient with a significant blood loss may appear normal during examination by first responders. Consequently, for every polytrauma victim with a significant mechanism of injury we assume substantial blood loss has occurred and life-threatening hemorrhage is progressing until we can prove the contrary. Second, a decision to begin damage control resuscitation (DCR), a costly, highly complex, and potentially dangerous intervention must often be reached with little time and without sufficient clinical information about the intended recipient. Whether to begin DCR in the prehospital phase remains controversial. Furthermore, DCR executed imperfectly has the potential to worsen serious derangements including acidosis, coagulopathy, and profound homeostatic imbalances that DCR is designed to correct. Additionally, transfusion of large amounts of homologous blood during DCR potentially disrupts immune and inflammatory systems, which may induce severe systemic autoinflammatory disease in the aftermath of DCR. Third, controversy remains over the composition of components that are transfused during DCR. For practical reasons, unmatched liquid plasma or freeze-dried plasma is transfused now more commonly than ABO-matched fresh frozen plasma. Low-titer type O whole blood may prove safer than red cell components, although maintaining an inventory of whole blood for possible massive transfusion during DCR creates significant challenges for blood banks. Lastly, as the primary principle of management of life-threatening hemorrhage is surgical or angiographic control of bleeding, DCR must not eclipse these definitive interventions.

Pathogen-reduced platelets in pediatric and neonatal patients: Demographics, transfusion rates, and transfusion reactions

BACKGROUND

Pathogen-reduced platelets (PR PLT) are the emerging standard for proactive transfusion-transmitted infection (TTI) mitigation. There is, however, continued hesitation to transfuse PR PLT in children due to limited published data. We report demographics, rates of transfusion, and transfusion reactions (TR) associated with FDA-approved PR PLT in pediatric and neonatal patients at an academic medical center.

METHODS

Retrospective review was performed for patients <18 years receiving at least one platelet over a 300-day period at a large, tertiary care hospital. Patients were transfused PR or conventional (CONV) PLT, based on inventory availability. Statistical analysis was performed using Fisher Exact Test.

RESULTS

During the study period, 191 patients received 1010 platelet transfusions (892 units). Sixty-eight patients received PR PLT only (1.3 units/patient, 95% confidence interval [CI] 1.1-1.5; 1.8 transfusions/patient, 95% CI 1.4-2.2), and 56 patients received CONV PLT only (1.4 units/patient, 95% CI 1.1-1.7; 1.6 transfusions/patient, 95% CI 1.3-1.9). Patients with hematologic malignancies undergoing chemotherapy/radiation and allogeneic hematopoietic stem cell transplant received the most platelet transfusions and more commonly received both platelet types. Of 506 PR PLT units, 5 TRs occurred; 386 CONV PLT resulted in two TRs (p = .7052). Of 51 neonates, 37 received PR PLT without adverse events, including 13 receiving phototherapy. No TTIs were identified in any group.

CONCLUSION

There was no significant difference in rates of transfusion or TRs between PR and CONV PLT. Our study provides additional evidence that PR PLT can be transfused to pediatric and neonatal patients without increasing the risk of acute adverse events.

Frozen and cold-stored platelets: reconsidered platelet products

Platelet transfusion, both prophylactic and therapeutic, is a key element in modern medicine. Currently, the standard platelet product for clinical use is platelet concentrates at room temperature (20-24°C) under gentle agitation. As this temperature favors bacterial growth, storage is limited to 5-7 days, which result in high wastage rate, and complicates inventory and product availability at remote areas. Frozen and/or cold storage would ameliorate those disadvantages by reducing the risk of bacterial contamination and by extending the product shelf-life to weeks or even years. Consequently, the usefulness in transfusion medicine of platelet cryopreservation and refrigeration, two old and scarcely used platelet storage approaches, is reemerging. Indeed, there have been substantial recent research efforts to characterize both cold and cryopreserved platelets. Most recent studies indicate that cryopreserved and cold platelets display a pro-coagulant profile that may produce the rapid hemostatic response which is needed in bleeding patients. Thus, it seems appropriate that blood banks and blood transfusion centers explore the possibility of split platelet inventories consisting of platelets stored at room temperature and cryopreserved and cold-stored platelets.

Supplemental findings of the 2019 National Blood Collection and Utilization Survey

INTRODUCTION

Supplemental data from the 2019 National Blood Collection and Utilization Survey (NBCUS) are presented and include findings on donor characteristics, autologous and directed donations and transfusions, platelets (PLTs), plasma and granulocyte transfusions, pediatric transfusions, transfusion-associated adverse events, cost of blood units, hospital policies and practices, and implementation of blood safety measures, including pathogen reduction technology (PRT).

METHODS

National estimates were produced using weighting and imputation methods for a number of donors, donations, donor deferrals, autologous and directed donations and transfusions, PLT and plasma collections and transfusions, a number of crossmatch procedures, a number of units irradiated and leukoreduced, pediatric transfusions, and transfusion-associated adverse events.

RESULTS

Between 2017 and 2019, there was a slight decrease in successful donations by 1.1%. Donations by persons aged 16-18 decreased by 10.1% while donations among donors >65 years increased by 10.5%. From 2017 to 2019, the median price paid for blood components by hospitals for leukoreduced red blood cell units, leukoreduced apheresis PLT units, and for fresh frozen plasma units continued to decrease. The rate of life-threatening transfusion-related adverse reactions continued to decrease. Most whole blood/red blood cell units (97%) and PLT units (97%) were leukoreduced.

CONCLUSION

Blood donations decreased between 2017 and 2019. Donations from younger donors continued to decline while donations among older donors have steadily increased. Prices paid for blood products by hospitals decreased. Implementation of PRT among blood centers and hospitals is slowly expanding.

Transfusion-associated adverse events and implementation of blood safety measures - findings from the 2017 National Blood Collection and Utilization Survey

BACKGROUND

Serious transfusion-associated adverse events are rare in the United States. To enhance blood safety, various measures have been developed. With use of data from the 2017 National Blood Collection and Utilization Survey (NBCUS), we describe the rate of transfusion-associated adverse events and the implementation of specific blood safety measures.

STUDY DESIGN AND METHODS

Data from the 2017 NBCUS were used with comparison to already published estimates from 2015. Survey weighting and imputation were used to obtain national estimates of transfusion-associated adverse events, and the number of units treated with pathogen reduction technology (PRT), screened for Babesia, and leukoreduced.

RESULTS

The rate of transfusion-associated adverse events requiring any diagnostic or therapeutic interventions was stable (275 reactions per 100,000 transfusions in 2015 and 282 reactions per 100,000 transfusions in 2017). In 2017 among US blood collection centers, 16 of 141 (11.3%) reported screening units for Babesia and 28 of 144 (19.4%) reported PRT implementation; 138 of 2279 (6.1%) hospitals reported transfusing PRT-treated platelets. In 2017, 134 of 2336 (5.7%) hospitals reported performing secondary bacterial testing of platelets (50,922 culture-based and 63,220 rapid immunoassay tests); in 2015, 71 of 1877 (3.8%) hospitals performed secondary testing (87,155 culture-based and 21,779 rapid immunoassay tests). Nearly all whole blood/red blood cell units and platelet units were leukoreduced.

CONCLUSIONS

Besides leukoreduction, implementation of most blood safety measures reported in this study remains low. Nationally, hospitals might be shifting from culture-based secondary bacterial testing to rapid immunoassays.

Remodelling whole blood processing through automation and pathogen reduction technology at the Luxembourg Red Cross

In 2014-2015, the Luxembourg Red Cross (LRC) implemented a fully automated system (FAS) able to process 4 whole blood units simultaneously, and a pathogen reduction technology (PRT) based on riboflavin and ultraviolet light to improve safety of platelet concentrates (PCs). In this observational study, the impact of both technologies to enable this centralised blood transfusion centre to provide safe and timely blood components supply for the whole country was analysed. Standard quality control parameters for blood components, productivity and safety were compared from data collected with the conventional semi- automated buffy coat method and with FAS/PRT. The FAS decreased processing time when compared with the buffy coat method and facilitated the daily routine at the LRC. Red blood cell concentrates, plasma units and PCs prepared with both methods were conform to the European Directorate for the Quality of Medicines & HealthCare specifications. PCs prepared by FAS showed high yields, with decreased variability when the device-related software (T-Pool Select) was used. PRT had minimal impact on platelet yields and product quality and induced no increase in transfusion reaction notifications. The FAS and PRT transformed the daily routine of blood component manufacture by allowing increased productivity and efficiency, notwithstanding resource containment and without impacting quality, yet promoting safety.