Platelet Contamination Research Articles

Evaluation of the Efficacy of Flow Cytometry in Detecting Bacterial Contamination in Platelets

Introduction: Bacterial contamination of platelet products is a major risk of infections in blood transfusion. Due to their storage conditions at room temperatures (22 to 24°C), cases of septicemia and even death caused by platelet injection have been reported. Therefore, use of appropriate diagnostic methods can improve the health of this product. In this study, flow cytometry was used to detect contaminated platelet units.
 Methods: This study was a diagnostic interventional type. 15 units of platelet concentrate was prepared at a minimum interval time after production. Staphylococcus epidermidis and Escherichia coli (E. coli) bacteria were each added to 6 platelet bags, with a concentration of 10 CFU / ml, while 3 bags were used as negative control. Platelets were stored in a shaking incubator at 22 - 24°C, for 0, 6, 24 and 48 hour-intervals after inoculation. Samples were then taken at 1 ml volume and evaluated by flow cytometry.
 Results: The sensitivity of the flow cytometry method to detect contaminated platelet units in infections with both Staphylococcus epidermidis and E. coli, in a 1 ml volume in all samples at 0, 6, 22 and 24 hours after inoculation, was 100%, and the number of bacteria increased in 24 hours of incubation, except for E. coli that decreased after 24 hours.
 Conclusion: This study shows that flow cytometry can be a useful method for detecting bacterial contamination in platelets, and can detect low concentrations (10 CFU / ml) of bacteria in small volumes of sample (ml) in a short time.

Plasma Transfusion Products and Contamination with Cellular and Associated Pro-Inflammatory Debris

Stored plasma products are widely regarded as being functionally acellular, obviating the need for leukoreduction. We tested the hypothesis that donor plasma is contaminated by leukocytes and platelets, which, after frozen storage, would release cellular debris in quantities sufficient to elicit significant pro-inflammatory responses. Samples of never-frozen liquid plasma from 2 regional Level I trauma centers were analyzed for leukocyte and platelet contamination. To determine if the cellular contamination and associated debris found in liquid plasma were at levels sufficient to evoke an innate immune response, known quantities of leukocytes were subjected to a freeze-thaw cycle, added to whole blood, and the magnitude of the inflammatory response was determined by induction of interleukin-6. Units of never-frozen plasma from 2 regional Level I trauma centers located in Alabama and Louisiana contained significant amounts of leukocyte contamination (Louisiana, n= 22; 17.3 ± 4.5 million vs Alabama, n= 22; 11.3 ± 2.2 million) and platelet contamination (Louisiana, n= 21; 0.86 ± 0.20 billion vs Alabama, n= 22; 1.0 ± 0.3 billion). Cellular debris from as few as 1 million leukocytes induced significant increases in interleukin-6 levels (R2= 0.74; p < 0.0001). Stored plasma units from trauma center blood banks were highly contaminated with leukocytes and platelets, at levels more than 15-fold higher than sufficient to elicit exvivo inflammatory responses. In light of paradigm shifts toward the use of more empiric plasma for treatment of hypovolemia, this study suggests that new manufacturing and quality-control processes are needed to eliminate previously unrecognized cellular contamination present in stored plasma products.

Labelling and Clinical Performance of Human Leukocytes Labelled with 99mTc-HMPAO Using Leukokit® with Gelofusine versus Leukokit® with HES as Sedimentation Agent.

The scintigraphy with radiolabelled autologous leukocytes (WBCs) is considered the gold-standard technique for imaging infections. Leukokit® is a commercially available, disposable, sterile kit for labelling WBCs ex vivo. In this kit, WBCs isolation from red blood cells (RBCs) was performed using poly(O-2-hydroxyethyl)starch (HES) as the RBCs sedimentation agent. Due to its poor availability, HES has been recently replaced by Gelofusine as the RBC sedimentation agent. The aim of this study was to compare the labelling efficiency and the diagnostic accuracy of WBCs labelled with Leukokit® with HES vs Leukokit® with Gelofusine. WBCs were isolated using HES or Gelofusine for 45 minutes and then purified from platelets (PLTs) and labelled with 1.1 ± 0.3 GBq of freshly prepared 99mTc-HMPAO. The following parameters were evaluated: the number and type of recovered WBCs, RBCs contamination, PLTs contamination, vitality of neutrophils, and chemotactic properties of neutrophils. Clinical comparison was performed between 80 patients (33 males; age 67.5 ± 14.2) injected with 99mTc-HMPAO-WBCs, using HES as the sedimentation agent, and 92 patients (38 males; age 68.2 ± 12.8) injected with 99mTc-HMPAO-WBCs using Gelofusine as the sedimentation agent. Patients were affected by prosthetic joint infections, peripheral bone osteomyelitis, or vascular graft infection. We compared radiolabelling efficiency (LE), final recovery yield (RY), and diagnostic outcome based on microbiology or 2-year follow-up. Results showed that HES provides the lowest RBCs and PLTs contamination, but Gelofusine provides the highest WBC recovery. Both agents did not influence the chemotactic properties of WBCs, and no differences were found in terms of LE and RY. Sensitivity, specificity, and accuracy were also not significantly different for WBCs labelled with both agents (diagnostic accuracy 90.9%, CI = 74.9–96.1 vs 98.3%, CI = 90.8–100, for HES and Gelofusine, respectively). In conclusion, Gelofusine can be considered a suitable alternative of HES for WBCs separation and labelling.

Microfluidic Immiscible Phase Filtration System for the Isolation of Small Numbers of Cells from Whole Blood.

Isolation of circulating tumor cells (CTCs) has generated clinical and academic interest due to the important role that CTCs play in cancer metastasis and diagnosis. Here, we present a PDMS and glass prototype of a microfluidic device for the immunomagnetic, immiscible phase filtration based capture, and isolation of MCF-7 breast cancer cells, from various sample matrices including PBS-based buffer, blood plasma, and unprocessed whole blood. Following optimization of surface energy of an oil-water interface, microfluidic geometry, and bead-binding kinematics, our microfluidic device achieved 95 ± 4% recovery of target cells from PBS-based buffer with 95% purity, 90 ± 3% recovery of target cells from blood plasma and recovery of ~70 ± 5% from unprocessed whole blood with purity >99% with 1 ml blood samples with 1,000 spiked target cells. From quantitative studies to assess the nonspecific carryover of contaminants from whole blood, we found that our system accomplishes a >175 fold depletion in platelets, >900 fold depletion in erythrocytes, and >1,700 fold depletion in leukocytes with respect to unprocessed whole blood, enabling us to avoid sample pre-processing. In addition, we found that ~95% of the isolated target cells were viable, making them suitable for subsequent molecular and cellular studies. We quantify and propose mechanisms for the carryover of platelet, erythrocyte, and leukocyte contamination in purified samples, rather than relying on sample pre-processing. These results validate the continued study of our platform for extraction of CTCs from patient samples and other rare cell isolation applications. © 2019 International Society for Advancement of Cytometry.

Transfusion-Transmitted Infections Reported to the National Healthcare Safety Network Hemovigilance Module.

Transfusion-transmitted infections (TTIs) can be severe and result in death. Transfusion-transmitted viral pathogen transmission has been substantially reduced, whereas sepsis due to bacterial contamination of platelets and transfusion-transmitted babesiosis may occur more frequently. Quantifying the burden of TTI is important to develop targeted interventions. From January 1, 2010, to December 31, 2016, health care facilities participating in the National Healthcare Safety Network Hemovigilance Module monitored transfusion recipients for evidence of TTI and recorded the total number of units transfused. Facilities use standard criteria to report TTIs. Incidence rates of TTIs, including for bacterial contamination of platelets and transfusion-transmitted babesiosis, are presented. One hundred ninety-five facilities reported 111 TTIs and 7.9 million transfused components to the National Healthcare Safety Network Hemovigilance Module. Of these 111 reports, 54 met inclusion criteria. The most frequently reported pathogens were Babesia spp in RBCs (16/23, 70%) and Staphylococcus aureus in platelets (12/30, 40%). There were 1.95 (26 apheresis, 4 whole blood derived) TTIs per 100 000 transfused platelet units and 0.53 TTI per 100 000 transfused RBC components, compared to 0.68 TTI per 100 000 all transfused components. Bacterial contamination of platelets and transfusion-transmitted babesiosis were the most frequently reported TTIs. Interventions that reduce the burden of bacterial contamination of platelets, particularly collected by apheresis, and Babesia transmission through RBC transfusion would reduce transfusion recipient morbidity and mortality. These analyses demonstrate the value and importance of facility participation in national recipient hemovigilance using standard reporting criteria.

Financial impact of alternative approaches to reduce bacterial contamination of platelet transfusions.

Bacterial contamination of platelets remains the leading infectious risk from blood transfusion. Pathogen reduction (PR), point-of-release testing (PORt), and secondary bacterial culture (SBC) have been proposed as alternative risk control strategies, but a comprehensive financial comparison has not been conducted. A Markov-based decision tree was constructed to model the financial and clinical impact of PR, PORt, and SBC, as well as a baseline strategy involving routine testing only. Hospitals were assumed to acquire leukoreduced apheresis platelets on Day 3 after collection, and, in the base case analysis, expiration would occur at the end of Day 5 (PR and SBC) or 7 (PORt). Monte Carlo simulations assessed the direct medical costs for platelet acquisition, testing, transfusion, and possible complications. Input parameters, including test sensitivity and specificity, were drawn from existing literature, and costs (2018 US dollars) were based on a hospital perspective. The total costs per unit acquired by the hospital under the baseline strategy, PR, PORt, and SBC were $651.45, $827.82, $686.33, and $668.50, respectively. All risk-reduction strategies decreased septic transfusion reactions and associated expenses, with the greatest reductions from PR. PR would add $191.09 in per-unit acquisition costs, whereas PORt and SBC would increase per-unit testing costs by $31.79 and $17.26, respectively. Financial outcomes were sensitive to platelet dating; allowing 7-day storage with SBC would lead to a cost savings of $12.41 per transfused unit. Results remained robust in probabilistic sensitivity analyses. All three strategies are viable approaches to reducing bacterially contaminated platelet transfusions, although SBC is likely to be the cheapest overall.

Surrogate markers and their correlation to bacterial contamination and other quality parameters in random-donor platelets by platelet-rich plasma method

Introduction: Bacterial contamination in platelet concentrates (PCs) occurs more frequently than other blood components because of several factors such as storage in oxygen permeable blood bags at 20°C–24°C with continuous agitation which facilitates bacterial growth compared to other blood components which are kept frozen or refrigerated which inhibits bacterial proliferation in them. The purpose of the study was to assess the incidence of bacterial contamination of random-donor PCs and factors associated with its contamination and see how well the surrogate markers such as pH and swirling correlate with the same. Methodology: This was a cross-sectional study which included randomly chosen 500 random-donor platelets (RDPs) in blood bank prepared by platelet-rich plasma method. The samples chosen for the study were from the RDPs on the 5th day of storage after their preparation. pH, platelet count, and swirling in platelets, which act as surrogate markers for bacterial contamination, were checked on the RDP units. About 1–3 ml of PCs was inoculated from the RDP units into labeled culture bottles (BD Bactec Peds Plus/F). Results: Among a total of 499 random-donor PCs that were cultured in the automated BACTEC system for the study, none of them were culture positive. Thirty RDP units in the study were visibly lipaemic whereas 93 RDP units were visibly reddish in appearance. PCs having volumes 70 ml did not affect the swirling, pH, and platelet counts. There was a statistically significant difference between mean pH with RDP units having swirling Grade 2 and 3 and platelet counts with RDP units having swirling Grade 1 and 2. Conclusion: Bacterial contamination though poses a significant risk is a very rare event in a meticulously prepared and stored PCs. Surrogate markers though useful in resource-constrained settings does not correlate optimally with the quality indicators.

Bacterial surveillance of apheresis platelets in South Africa (January 2011 to December 2016)

BackgroundGlobally, bacterial contamination of platelets remains the major transfusion‐related infectious risk. Limited data are available from low‐middle income countries. The South African National Blood Service routinely tests a percentage of apheresis platelets for bacterial contamination. We report on contamination rates from January 2011 to December 2016.MethodsA retrospective analysis of the surveillance data from apheresis platelets was performed. Two to 4 ml of each apheresis product was collected aseptically and divided equally into an aerobic and anaerobic culture bottle using the BacT/ALERT (bioMerieux) or BACTEC™ (Beckton Dickinson) systems. Bacterial identification was done using the MicroScan (Beckman Coulter) system.ResultsA total of 87 841 apheresis platelets were collected between 2011 and 2016 of which 18% were tested. The average positive culture rate was 2·7%, ranging between 0·6% (2011) and 5·22% (2015). Gram‐positive bacteria constituted 94% of all isolates (269/285), ten (4%) gram‐negative bacteria and 6 (2%) fungi were detected. The most common bacterial isolates were Cutibacterium acnes (35%), coagulase‐negative Staphylococci (26%), Bacillus spp. (8%), Corynebacteria spp. (8%). A total of nine highly pathogenic bacteria were isolated: two Acinetobacter spp, one each of Enterobacter spp., Serratia spp., Klebsiella spp., one Staphylococcus aureus and three Listeria spp. Average time to positivity for bacteria was 5·9 days. No cases of sepsis or death were reported during this time.ConclusionBacterial contamination rates, mostly due to gram‐positive bacteria, increased since 2011. Bacterial screening must be aligned with international recommendations, and novel technologies should be explored to reduce the residual risk.

Combining culture and microbead‐based immunoassay for the early and generic detection of bacteria in platelet concentrates

Despite current preventive strategies, bacterial contamination of platelets is the highest residual infectious risk in transfusion. Bacteria can grow from an initial concentration of 0.03-0.3 colony-forming units (CFUs)/mL up to 108 to 109 CFUs/mL over the product shelf life. The aim of this study was to develop a cost-effective approach for an early, rapid, sensitive, and generic detection of bacteria in platelet concentrates. A large panel of bacteria involved in transfusion reactions, including clinical isolates and reference strains, was established. Sampling was performed 24 hours after platelet spiking. After an optimized culture step for increasing bacterial growth, a microbead-based immunoassay allowed the generic detection of bacteria. Antibody production and immunoassay development took place exclusively with bacteria spiked in fresh platelet concentrates to improve the specificity of the test. Antibodies for the generic detection of either gram-negative or gram-positive bacteria were selected for the microbead-based immunoassay. Our approach, combining the improved culture step with the immunoassay, allowed sensitive detection of 1 to 10 CFUs/mL for gram-negative and 1 to 102 CFUs/mL for gram-positive species. In this study, a new approach combining bacterial culture with immunoassay was developed for the generic and sensitive detection of bacteria in platelet concentrates. This efficient and easily automatable approach allows tested platelets to be used on Day 2 after collection and could represent an alternative strategy for reducing the risk of transfusion-transmitted bacterial infections. This strategy could be adapted for the detection of bacteria in other cellular products.

Detection of bacterial contamination in platelet concentrates from Brazilian donors by molecular amplification of the ribosomal 16S gene.

The aim of our work was to establish a semi-automated high-throughput DNA amplification method for the universal screening of bacteria in platelet concentrates (PCs). Among cases of transfusion transmission of infectious agents, bacterial contamination ranks first in the number of events, morbidity and mortality. Transmission occurs mainly by transfused PCs. Automated culture is adopted by some blood banks for screening of bacterial contamination, but this procedure is expensive and has a relatively long turnaround time. PCs were spiked with suspensions of five different bacterial species in a final concentration of 1 and 10 colony-forming units (CFU) per millilitre. After incubation, the presence of bacteria was investigated by real-time polymerase chain reaction (PCR) and by the Enhanced Bacterial Detection System (eBDS, Pall) assay as a reference method. Real-time PCR amplification was performed with a set of universal primers and probes targeting the 16S rRNA gene. Co-amplification of human mitochondrial DNA served as an internal control. Using the real-time PCR method, it was possible to detect the presence of all bacterial species tested with an initial concentration of 10CFU mL-1 24 h after contamination, except for Staphylococcus hominis. The PCR assay also detected, at 24 h, the presence of Serratia marcescens and Enterobacter cloacae with an initial concentration of 1CFU mL-1 . The real-time PCR assay may be a reliable alternative to conventional culture methods in the screening of bacterial contamination of PCs, enabling bacterial detection even with a low initial concentration of microorganisms.

Comparing two blood culture systems for the detection of bacterial contamination in platelet concentrates.

The transfusion of platelet concentrates (PCs) contaminated with bacteria may cause serious, and even fatal, septic reactions in patients. The aim of this study was to compare the VersaTREK with the BACTEC FX automated culture systems for screening bacterial contamination, directly after the delay of 24 hours of preparation to obtain the final pooled buffy coat PCs, to prevent transfusion-transmitted bacterial infections. Seven bacterial strains were each inoculated into five replicate pooled buffy coat PCs at approximately 100 colony-forming units/unit, and 5- or 10-mL samples were inoculated into duplicate aerobic culture bottles. The time and detection rates were compared between BACTEC FX, as a reference method, and VersaTREK. Time to detection was significantly shorter using VersaTREK for most species detected by both systems for the volumes tested. Of 70 VersaTREK cultures, 69 (98.57% detection rate) were positive after 24 hours of incubation with the 5-mL sample. In contrast, the BACTEC FX system detected all positive samples in PCs for the volume of 10 mL, although seven samples were false negatives for the 5-mL volume. The VersaTREK system compared favorably to the BACTEC FX system for 5-mL volumes (p < 0.05) and could be considered a potential method for detecting bacterial contamination in PC samples directly after 24 hours of preparation of the final pooled buffy coat PCs.

Microbial safety of cellular therapeutics—lessons from over ten years’ experience in microbial safety of platelet concentrates

Bacterial safety of cellular preparations, including blood products and cellular therapeutics, presents ongoing challenges for physicians, manufacturers and regulators. Although there have been many new approaches to enhance the microbial safety of cellular products during the last decade, established methods for microbiological control still need to be fully adapted to the special circumstances of cellular preparations. The experience from transfusion medicine regarding microbial safety of blood components has demonstrated the variety of problems and risk factors for the development of new strategies for microbial safety. Special attention has been given to the prevention and detection of bacterial contamination of platelet concentrates. But so far, none of the targeted strategies for rapid detection or pathogen reduction have become routinely implemented worldwide, in part at least because development and requirements of new technologies and their implementation into the routine setting are a whole different problem. But factors including the short shelf life and nontraditional lot sizes for cellular and gene therapy products are driving the need for rapid microbiological methods. In conclusion, lessons from the microbial safety of platelet concentrates enable us to understand that the detection or reduction in bacteria represents a more difficult challenge in comparison with viruses. Recent regulatory changes demonstrate that we are getting closer to the goal of a shift from the traditional view of sterility evaluation (identify and inactivate anything and everything) to a new thinking about microbiological control.

Bacterial contamination of platelet products in Dongguan Blood Center, Guangdong Province of China

Background: Due to the importance of their preservation and collection methods, it is critical to assess accurately the risk of bacterial contamination of pooled platelets and apheresis platelets. The incidence of bacterial contamination was observed after four preventive measures (FPM) (including: sterilizing donation environment, screening donors, depleting white blood cells from pooled platelets, and removing the first 15 ml of collected platelet) were taken. Methods: Platelet product samples (pooled and apheresis platelet products) from Dongguan Blood Center were tested by bacterial cultures including initial culture, subculture and identification. If initial culture was positive, subculture would be performed, and if subculture was positive, bacterial identification would be done. 3073 platelet samples were examined in 2006. Platelet samples were collected in 2006 and in 2007 until 2016 after the introduction of FPM. Recipient’s blood and transfused platelets were tested for bacterial cultures when adverse reactions occurred after platelet transfusion. Results: In 2006, 0.72% and 0.47% bacterial contamination were found in pooled platelets and apheresis platelets, respectively. A total of 63 out of 28,711 (0.22%) bacterial contaminations were detected from 2006 to 2016 in pooled and apheresis platelets. From 2007 to 2016, the positive rates of contaminated platelet products declined significantly to 0.33% (pooled platelets) and 0.14% (apheresis platelets). Only 44 positive samples could be identified after the introduction of FPM. In 50 patients with post-platelet transfusion adverse reaction, no bacterial contamination could be identified. Conclusions: Our study demonstrated the improvement of platelet transfusion safety by FPM, The rate of bacterial contamination in pooled platelets is higher than that of apheresis platelets.

Late sampling for automated culture to extend the platelet shelf life to 5 days in Germany.

Bacterial contamination of platelet concentrates (PCs) is still a major challenge in transfusion medicine. Different methodologic concepts and screening strategies have been developed and investigated concerning their usability. We evaluated the feasibility of BacT/ALERT automated culture (BacT/A, bioMérieux) with late sampling after 3 days at the earliest. Twenty-four bacterial strains isolated from PCs and six relevant strains from reference stocks were spiked into apheresis-derived PCs (10-60 colony-forming units [CFU]/bag). Sampling was performed after 3 days, and bacterial detection was investigated using the two detection methods (BacT/A and BactiFlow [BF], bioMérieux). The maximum time-to-result of BacT/A was set to less than 12 hours. All medium- or high-pathogenic strains are capable of proliferating to high titers, and 100% of contaminated samples were detected by BF and BacT/A (6 to ≤12 h incubation); lower detection rates of BacT/A were obtained within 6 hours of incubation (≤6 h: 76.2-93.4%). The majority of low-pathogenic isolates are also capable of growing in PCs (89.7%), showing a detection rate of 74.3% for BF versus 54.3% for BacT/A (6 to ≤12 h incubation). BacT/A failed to detect bacteria within 6 hours of incubation. Certainly, a small number of strains did not grow under PC storage conditions and were detectable by BacT/A only with increased detection times. Late sampling after 3 days at the earliest, combined with reduced BacT/A incubation following the negative-to-date concept, offer an alternative opportunity to extend the shelf life of PCs from 4 to 5 days in Germany. The sensitivity of BacT/A with late sampling is nearly comparable to BF; the time-to-result is considerably longer.

Implementation of secondary bacterial culture testing of platelets to mitigate residual risk of septic transfusion reactions.

Bacterial contamination of platelets remains a major transfusion-associated risk despite long-standing safety measures in the United States. We evaluated an approach using secondary bacterial culture (SBC) to contend with residual risk of bacterial contamination. Phased implementation of SBC was initiated in October 2016 for platelets (all apheresis collected) received at our institution from the blood donor center (Day 3 post collection). Platelet products were sampled aseptically (5 mL inoculated into an aerobic bottle [BacT/ALERT BPA, BioMerieux, Inc.]) by the blood bank staff upon receipt, using a sterile connection device and sampling kit. The platelet sample was inoculated into an aerobic blood culture bottle and incubated at 35°C for 3 days. The cost of SBC was calculated on the basis of consumables and labor costs at time of implementation. In the 13 months following implementation (October 6, 2016, to November 30, 2017), 23,044/24,653 (93.47%) platelet products underwent SBC. A total of eight positive cultures were detected (incidence 1 in 2881 platelet products), seven of which were positive within 24 hours of SBC. Coagulase negative Staphyloccus spp. were identified in four cases. Five of the eight cases were probable true positive (repeat reactive) and interdicted (cost per averted case was US$77,935). The remaining three cases were indeterminate. No septic transfusion reactions were reported during the observation period. We demonstrate the feasibility of SBC of apheresis platelets to mitigate bacterial risk. SBC is lower cost than alternative measures (e.g., pathogen reduction and point-of-release testing) and can be integrated into workflow at hospital transfusion services.

Efforts Toward Elimination of Infectious Agents in Blood Products.

The US blood supply has never been safer. This level of safety depends on a multifaceted approach including blood donor screening, sensitive infectious disease testing, and good manufacturing practice. However, risks remain for transfusion-transmitted infections due to bacterial contamination of platelets and emerging diseases. Thus, ongoing improvements in screening and testing are required. Newer pathogen reduction technologies have shown promise in further ameliorating the safety of the blood supply.

Red blood cells are dynamic reservoirs of cytokines

Red blood cells (RBCs) have been shown to affect immune function and can induce inflammatory responses after transfusion. The transfusion of washed RBCs can significantly reduce adverse effects, however, the soluble factors that may mediate these effects have not been identified. Previous studies have identified, but not quantified, a small number of chemokines associated with RBCs. We isolated RBCs from healthy volunteers and quantified of a panel of 48 cytokines, chemokines, and growth factors in the lysate, cytosol, and conditioned media of these cells using Luminex® technology. This analysis revealed that, after correcting for white blood cell and platelet contamination, 46 cytokines were detected in RBC lysates, and the median concentration in RBCs was 12-fold higher than in the plasma. In addition, extensive washing of RBCs, such as that performed in proteomics analyses or prior to some RBC transfusions, significantly attenuated the release of six cytokines following incubation at 37 °C. This supports the hypothesis that, alongside its gas exchange function, RBCs play a role in cytokine signalling. This discovery may help supplement disease biomarker research and may shed light on adverse inflammatory processes that can follow RBC transfusion.

Nationwide Implementation of Pathogen Inactivation for All Platelet Concentrates in Switzerland

Introduction: Bacterial contamination of platelet concentrates (PCs) has been identified as the most prevalent transfusion-associated infectious risk. To prevent PC-related septic transfusion reactions, the Intercept® pathogen inactivation procedure was introduced for all PCs in Switzerland in 2011. Methods: Based on numbers of transfused units and mandatorily reported adverse events with high imputability, we compare the risks associated with transfusion of conventional PCs (cPCs) and pathogen-inactivated PCs (PI-PCs). Results: From 2005 to 2011, a total of 158,502 cPCs have been issued in Switzerland, and 16 transfusion-transmitted bacterial infections (including 3 fatalities) were reported. This corresponds to a morbidity and mortality rate of ca. 1:9,900 and 1:52,800, respectively. From 2011 to 2016, a total of 205,574 PI-PCs have been issued, and no transfusion-transmitted bacterial infection was reported. Despite continuously increasing transfusion reaction rates per 1,000 RBC and plasma issued between 2008 and 2016, we observed reductions of 66% for life-threatening and fatal reactions and of 26% for all high-imputability transfusion reactions related to PI-PCs as compared to cPCs. No increased rates of bleeding or clinical observations of ineffectiveness of PI-PCs have been reported. After implementation of PI-PCs, the annual increase in platelet usage per 1,000 inhabitants decelerated. Discussion: Swiss hemovigilance data confirm a favorable safety profile of the nationwide introduced Intercept pathogen inactivation procedure and its reliable prevention of septic transfusion reactions and fatalities due to bacterially contaminated PCs.

Purity of Plasma as a Sample for Neuropsychiatric Omics Studies Based on Virchow's Cellular Principle

As an idea to ensure the success of OMICS research, there is Virchow's pathological ideas of physical disease. This idea is that one cell, a group of cells, a substance, and a group of substances are specific for each disease. Based on this idea, it can be inferred that the unity and purity of the sample and the disease used are extremely important factors. In this study, the aim is to show how the difference in trivial centrifugal conditions of whole blood affected the plasma concentration of Phosphoethanolamine (PEA), a biomarker of depression shown in our previous study, It turned out that the value of PEA increases when the rotor is a swing type, or when the temperature at the time of centrifugation is set at 4°C. This increase might be due to platelet contamination in isolated plasma. Therefore, especially when the researchers are looking to discover an unknown marker, special attention should be paid to sample.

Ensuring sample quality for blood biomarker studies in clinical trials: a multicenter international study for plasma and serum sample preparation.

Sample quality is critical for biomarker detection in oncology, and platelet degradation and contamination in plasma have a remarkable impact on the ability to accurately quantify many blood-based biomarkers. Platelet factor 4 (PF4) can be used as an indicator to monitor sample quality. This multicenter study aimed to determine the impact of critical components of the blood sample handling process on platelet degradation/contamination and to establish an optimal method for collecting platelet-poor plasma samples. At each of six participating centers, blood samples were drawn from 12-13 healthy volunteers. Serum and plasma samples were prepared from whole blood samples using nine different methods that have been commonly used in ongoing multicenter trials. PF4 levels in the prepared samples were measured by enzyme-linked immunosorbent assay (ELISA). Paired t-tests were used for statistical analysis. Blood samples were collected from 74 subjects enrolled in six centers. PF4 levels were significantly higher in serum samples than in plasma samples (P<0.001), in plasma samples from blood that sat at room temperature for 5 minutes (P=0.021), in plasma samples prepared at an insufficient centrifugal force (P<0.001), and in plasma samples prepared from blood that sat for longer than 4 hours on ice (P=0.001). For each method, the PF4 levels did not differ significantly among the centers or between Chinese and American subjects. The methods that resulted in normal levels of PF4 involved keeping blood samples on ice for 30 minutes to <4 hours and centrifugation at 2,500-3,000 ×g for 30 min. This multicenter study evaluated multiple blood sample handling conditions for minimizing platelet degradation during plasma serum preparation and determined an optimal method for preparing platelet-poor plasma. The findings of this study can be applied in future blood biomarker studies.