ALBERT

Description: Introduction As of June 2015 the FDA has approved an alternative procedure under 21 CFR 640.120 that allows for storage of apheresis platelets at refrigerator temperature (1-6 C; 4°C) without agitation for up to 3 days for use in the resuscitation of actively bleeding patients. Understanding underlying mechanisms responsible for enhanced hemostatic function at 4°C will be critical for such improvements in platelet transfusion. We hypothesized that 4°C platelets display better mitochondrial respiratory function for up to 7 days compared to standard 5-day RT platelets and that mitochondrial gene expression differences between RT and 4°C -stored platelets will correlate with mitochondrial function. Methods Platelets were collected from healthy donors by apheresis according to an IRB-approved protocol. Apheresis platelets (AP) were rested for 1 h before allocation into platelet minibags (Blood Cell Storage, Seattle, WA) and stored for 4 storage durations (Baseline (BL), Day 3, 5, and 7). Mitochondrial respiration, maximal oxygen utilization, and individual mitochondrial complex-dependent respiration were assessed with high-resolution respirometry (O2k, Oroboros). Mitochondrial ROS generation in response to storage condition or stimulation (to assess oxidative burst capacity as a measure of function) was visualized with fluorescent imaging and assayed with flow cytometry using a superoxide stain (Life Technologies). Total RNA was extracted both immediately following apheresis (BL) and on Day 5 from RT and 4°C-stored platelets using Trizol (Molecular Research Center, Cincinnati, OH) after centrifuging the platelets at 900 x g for 10 min. Platelet RNA was quantified using the NanoDrop 2000. RNA quality was examined using gel electrophoresis with the Reliant Gel System (Cambrex, Rockland, ME). Platelet mitochondrial gene expression analysis was evaluated using the 96-well RT2 Profiler PCR Array (Qiagen, Valencia, CA) which profiled 84 mitochondria-focused targets and 12 control genes per sample. Gene expression data analysis was based on the ΔΔCt method with normalization of the raw data to housekeeping genes located on each 96-well plate. Results Mitochondrial respiration was lower in platelets stored at 4°C compared to RT on Days 3, 5, and 7 (Day 5= -57%±0.3; P 〈 0.05), demonstrating that refrigeration slows metabolism. Additionally, maximal mitochondrial oxygen utilization (electron transport system capacity) was better preserved in platelets stored at 4°C (Figure 1). Fluorescent imaging and flow cytometry demonstrated that mROS generation was higher in RT-stored platelets compared to 4°C, reflecting mitochondrial damage. Mitochondrial burst during de novo mROS generation due to stimulation was also preserved at 4°C. Mitochondrial gene expression studies revealed distinct differences in expression profiles for 4°C versus RT-stored platelets after 5 days of storage when normalized to BL measures. Storage at 4°C resulted in significantly greater preservation of 15 gene products at Day 5 (P

Description: Introduction The acute traumatic coagulopathy (ATC) which develops within 30 min following severe trauma with tissue damage and shock is defined by an increased prothrombin time (PT) and international normalized ratio (INR). While reduced thrombin might be expected in conjunction with elevated PT, recent clinical studies reveal paradoxically elevated thrombin generation potential in patients with ATC. We therefore hypothesized that the quantity of thrombin and the timing of thrombin-fibrinogen interactions both have an impact on clot quality; the exuberant production of thrombin found in trauma results in improper clot formation. Methods In vitro studies were conducted in human blood products and simplified synthetic plasma (consisting of purified human coagulation factors in HEPES buffered saline). Turbidimetry was used to observe fibrin crosslinking, while thromboelastography (TEG) was used to quantify clot formation parameters. Quantitation of fibrin(ogen) degradation products (FDPs) was conducted with the STA-R Evolution coagulation analyzer and by ELISA. A fluorogenic substrate was used to observe thrombin generation. Results Increasing the amount of prothrombin or thrombin (0-1400nM) in prothrombin-immunodepleted citrated plasma resulted in reduced clot times. The same dose response was examined in a buffered mixture of fibrinogen (300 mg/dl), FXIII (31.25nM), Ca2+ (2mM), and FXa (170nM-only used with prothrombin samples). However, while increasing prothrombin increased clot strength in both FII-deficient plasma and in the synthetic plasma, direct addition of thrombin decreased clot strength and by 3-fold at 1000nM versus 100nM (Figure 1; *p

Description: Background The platelet storage lesion is mitigated by refrigeration in platelet additive solutions (PAS), but questions remain regarding effects of cold storage (4°C) on mitochondrial function. Understanding underlying mechanisms responsible for enhanced hemostatic function of 4°C-stored PAS platelets will be critical for such improvements in platelet transfusion. We hypothesized that storage of platelet concentrates at 4°C leads to GPIIb-IIIa activation and thus aggregate formation through fibrinogen binding, and that this could be prevented by storing platelets in platelet additive solution (PAS) without compromising platelet function. Methods Apheresis platelets in plasma (AP) or apheresis platelets in PAS were stored at 22°C or 4°C for up to 15 days. Measurements include platelet counts, blood gases, flow cytometry analysis, intracellular reactive oxygen species (ROS) levels, and high resolution respirometry. To explore the effect of fibrinogen on storage, platelets were treated with abciximab to inhibit GPIIb-IIIa binding and aggregation. Donor fibrinogen levels were measured before being collected in PAS; samples were separated into minibags for comparison of control 4°C PAS-stored platelets to 4°C PAS-stored platelets with fibrinogen added back to original donor levels (PAS-FBN). Results Mitochondrial respiration was lower in platelets stored at 4°C compared to 22°C in both AP and PAS; however, PAS-stored platelets retained lower mitochondrial respiration over the time course. Additionally, maximal mitochondrial oxygen utilization (oxidative burst capacity) was better preserved in 4°C-stored platelets; PAS demonstrated less overall mitochondrial exhaustion at 4°C compared to 4°C-AP samples (Figure 1). PAS-FBN resulted in reduced oxidative burst capacity over 15 days of storage which was consistent with loss of platelet function observed through flow cytometry analysis including increased phosphatidylserine expression, microparticles, and GPIb shedding. Mitochondrial intracellular ROS levels were lower in all 4°C-stored samples compared to their respective RT-stored groups. PAS-FBN resulted in significantly lower platelet counts (Day 5: BL= 1.1x106±.04plt/µL, PAS = 1.1 x106±.06plt/µL, PAS-FBN = .61 x106±.06plt/µL; P

Description: Fluid resuscitation improves clinical outcomes of burn patients; however, its execution in resource-poor environments may have to be amended with limited-volume strategies. Liver dysfunction is common in burn patients and gut dysbiosis is an understudied aspect of burn sequelae. Here, the swine gut microbiota and liver transcripts were investigated to determine the impact of standard-of-care modified Brooke (MB), limited-volume colloid (LV-Co), and limited-volume crystalloid (LV-Cr) resuscitation on the gut microbiota, and to evaluate its' potential relationship with liver dysfunction. Independent of resuscitation strategy, bacterial diversity was reduced 24 h post-injury, and remained perturbed at 48 h. Changes in community structure were most pronounced with LV-Co, and correlated with biomarkers of hepatocellular damage. Hierarchical clustering revealed a group of samples that was suggestive of dysbiosis, and LV-Co increased the risk of association with this group. Compared with MB, LV-Co and LV-Cr significantly altered cellular stress and ATP pathways, and gene expression of these perturbed pathways was correlated with major dysbiosis-associated bacteria. Taken together, LV-Co resuscitation exacerbated the loss of bacterial diversity and increased the risk of dysbiosis. Moreover, we present evidence of a linkage between liver (dys)function and the gut microbiota in the acute setting of burn injury.