Every year more than 500,000 deaths are attributed to trauma worldwide and severe hemorrhage is present in most of them. Transfused platelets have been shown to improve survival in trauma patients, although its mechanism is only partially known. Platelet derived-extracellular vesicles (PEVs) are small vesicles released from platelets upon activation and/or mechanical stimulation and many of the benefits attributed to platelets could be mediated through PEVs. Based on the available literature, we hypothesized that transfusion of human PEVs would promote hemostasis, reduce blood loss and attenuate the progression to hemorrhagic shock following severe trauma. In this study, platelet units from four different donors were centrifuged to separate platelets and PEVs. The pellets were washed to obtain plasma-free platelets to use in the rodent model. The supernatant was subjected to tangential flow filtration for isolation and purification of PEVs. PEVs were assessed by total count and particle size distribution by Nanoparticle Tracking Analysis (NTA) and characterized for cells of origin and expression of EV specific-surface and cytosolic markers by flow cytometry. The coagulation profile from PEVs was assessed by calibrated automated thrombography (CAT) and thromboelastography (TEG). A rat model of uncontrolled hemorrhage was used to compare the therapeutic effects of 8.7 × 10⁸ fresh platelets (FPLT group, n = 8), 7.8 × 10⁹ PEVs (PEV group, n = 8) or Vehicle (Control, n = 16) following severe trauma. The obtained pool of PEVs from 4 donors had a mean size of 101 ± 47 nm and expressed the platelet-specific surface marker CD41 and the EV specific markers CD9, CD61, CD63, CD81 and HSP90. All PEV isolates demonstrated a dose-dependent increase in the rate and amount of thrombin generated and overall clot strength. In vivo experiments demonstrated a 24% reduction in abdominal blood loss following liver trauma in the PEVs group when compared with the control group (9.9 ± 0.4 vs. 7.5 ± 0.5 mL, p < 0.001>). The PEV group also exhibited improved outcomes in blood pressure, lactate level, base excess and plasma protein concentration compared to the Control group. Fresh platelets failed to improve these endpoints when compared to Controls. Altogether, these results indicate that human PEVs provide pro-hemostatic support following uncontrolled bleeding. As an additional therapeutic effect, PEVs improve the outcome following severe trauma by maintaining hemodynamic stability and attenuating the development of ischemia, base deficit, and cardiovascular shock.

BACKGROUND: Platelet (Plt)-derived extracellular vesicles (Plt-EVs) have hemostatic properties similar to Plts. In addition to hemostasis, Plts also function to stabilize the vasculature and maintain endothelial cell (EC) barrier integrity. We hypothesized that Plt-EVs would inhibit vascular EC permeability, similar to fresh Plts. To investigate this hypothesis, we used in vitro and in vivo models of vascular endothelial compromise and bleeding.METHODS: In the vitro model, Plt-EVs were isolated by ultracentrifugation and characterized for Plt markers and particle size distribution. Effects of Plts and Plt-EVs on endothelial barrier function were assessed by transendothelial electrical resistance measurements and histological analysis of endothelial junction proteins. Hemostatic potential of Plt-EVs and Plts was assessed by multiple electrode Plt aggregometry. Using an in vivo model, the effects of Plts and Plt-EVs on vascular permeability and bleeding were assessed in non-obese diabetic-severe combined immunodeficient (NOD-SCID) mice by an established Miles assay of vascular permeability and a tail snip bleeding assay.RESULTS: In the in vitro model, Plt-EVs displayed exosomal size distribution and expressed Plt-specific surface markers. Platelets and Plt-EVs decreased EC permeability and restored EC junctions after thrombin challenge. Multiplate aggregometry revealed that Plt-EVs enhanced thrombin receptor–activating peptide-mediated aggregation of whole blood, whereas Plts enhanced thrombin receptor–activating peptide–, arachidonic acid–, collagen-, and adenosine diphosphate–mediated aggregation. In the in vivo model, Plt-EVs are equivalent to Plts in attenuating vascular endothelial growth factor (VEGF)-A–induced vascular permeability and uncontrolled blood loss in a tail snip hemorrhage model.CONCLUSION: Our study is the first to report that Plt-EVs might provide a feasible product for transfusion in trauma patients to attenuate bleeding, inhibit vascular permeability, and mitigate the endotheliopathy of trauma.

Background: Endothelial dysfunction during hemorrhagic shock (HS) is associated with loss of cell-associated syndecan-1 (Sdc1) and hyperpermeability. Fresh frozen plasma (FFP) preserves Sdc1 and reduces permeability following HS, although the key mediators remain unknown. Antithrombin III (ATIII) is a plasma protein with potent anti-inflammatory and endothelial protective activity. We hypothesized that the protective effects of FFP on endothelial Sdc1 and permeability are mediated, in part, through ATIII. Methods: ATIII and Sdc1 were measured in severely injured patients upon admission (N = 125) and hospital day 3 (N = 90) for correlation analysis. In vitro effects of ATIII on human lung microvascular endothelial cells (HLMVECs) were determined by pretreating cells with vehicle, FFP, ATIII-deficient FFP, or purified ATIII followed by TNFα stimulation. Sdc1 expression was measured by immunostaining and permeability by electrical impedance. To determine the role of ATIII in vivo, male mice were subjected to a fixed pressure exsanguination model of HS, followed by resuscitation with FFP, ATIII-deficient FFP, or ATIII-deficient FFP with ATIII repletion. Lung Sdc1 expression was assessed by immunostaining. Results: Pearson correlation analysis showed a significant negative correlation between plasma levels of Sdc1 and ATIII (R = −0.62; P < 0.0001) in injured patients on hospital day 3. Also, in vitro, FFP and ATIII prevented TNFα-induced permeability (P < 0.05 vs TNFα) in HLMVECs. ATIII-deficient FFP had no effect; however, ATIII restoration reestablished its protective effects in a dose-dependent manner. Similarly, FFP and ATIII prevented TNFα-induced Sdc1 shedding in HLMVECs; however, ATIII-deficient FFP did not. In mice, Sdc1 expression was increased following FFP resuscitation (1.7 ± 0.5, P < 0.01) vs. HS alone (1.0 ± 0.3); however, no improvement was seen following ATIII-deficient FFP treatment (1.3 ± 0.4, P = 0.3). ATIII restoration improved Sdc1 expression (1.5 ± 0.9, P < 0.05) similar to that of FFP resuscitation. Conclusions: ATIII plays a role in FFP-mediated protection of endothelial Sdc1 expression and barrier function, making it a potential therapeutic target to mitigate HS-induced endothelial dysfunction. Further studies are needed to elucidate the mechanisms by which ATIII protects the endothelium.

Background: The increased popularity and ubiquitous use of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) for the treatment of diabetes, heart failure, and obesity has led to significant concern for increased risk for perioperative aspiration, given their effects on delayed gastric emptying. This concern is highlighted by many major societies that have published varying guidance on the perioperative management of these medications, given limited data. We conducted a scoping review of the available literature regarding the aspiration risk and aspiration/regurgitant events related to GLP-1 RAs. Methods: A librarian-assisted search was performed using five electronic medical databases (PubMed, Embase, and Web of Science Platform Databases, including Web of Science Core Collection, KCI Korean Journal Database, MEDLINE, and Preprint Citation Index) from inception through March 2024 for articles that reported endoscopic, ultrasound, and nasogastric evaluation for increased residual gastric volume retained food contents, as well as incidences of regurgitation and aspiration events. Two reviewers independently screened titles, abstracts, and full text of articles to determine eligibility. Data extraction was performed using customized fields established a priori within a systematic review software system. Results: Of the 3712 citations identified, 24 studies met eligibility criteria. Studies included four prospective, six retrospective, five case series, and nine case reports. The GLP-1 RAs reported in the studies included semaglutide, liraglutide, lixisenatide, dulaglutide, tirzepatide, and exenatide. All studies, except one case report, reported patients with confounding factors for retained gastric contents and aspiration, such as a history of diabetes, cirrhosis, hypothyroidism, psychiatric disorders, gastric reflux, Barrett’s esophagus, Parkinson’s disease, dysphagia, obstructive sleep apnea, gastric polyps, prior abdominal surgeries, autoimmune diseases, pain, ASA physical status classification, procedural factors (i.e., thyroid surgery associated with risk for nausea, ketamine associated with nausea and secretions), and/or medications associated with delayed gastric emptying (opioids, anticholinergics, antidepressants, beta-blockers, calcium channel blockers, DPP-IV inhibitors, and antacids). Of the eight studies (three prospective and five retrospective) that evaluated residual contents in both GLP-1 users and non-users, seven studies (n = 7/8) reported a significant increase in residual gastric contents in GLP-1 users compared to non-users (19–56% vs. 5–20%). In the three retrospective studies that evaluated for aspiration events, there was no significant difference in aspiration events, with one study reporting aspiration rates of 4.8 cases per 10,000 in GLP-1 RA users compared to 4.6 cases per 10,000 in nonusers and the remaining two studies reporting one aspiration event in the GLP-1 RA user group and none in the non-user group. In one study that evaluated for regurgitation or reflux by esophageal manometry and pH, there was no significant difference in reflux episodes but a reduction in gastric acidity in the GLP-1 RA user group compared to the non-user group. Conclusions: There is significant variability in the findings reported in the studies, and most of these studies include confounding factors that may influence the association between GLP-1 RAs and an increased risk of aspiration and related events. While GLP-1 RAs do increase residual gastric contents in line with their mechanism of action, the currently available data do not suggest a significant increase in aspiration and regurgitation events associated with their use and the withholding of GLP-1 RAs to reduce aspiration and regurgitation events, as is currently recommended by many major societal guidelines. Large randomized controlled trials (RCTs) may be helpful in further elucidating the impact of GLP-1 RAs on perioperative aspiration risk.

Trauma patients are often affected by a hypocoagulable condition referred to as trauma-induced coagulopathy (TIC) for which few therapeutic options exist. One available treatment is fresh platelets transfusion, although it is not efficacious enough and has a number of limitations. Therefore, we reviewed the literature to propose an alternative therapy based on platelet-derived microvesicles (PMVs), which are cellular fragments surrounded by extracellular membrane and filled with cytoplasmic content. This concept is supported by a large number of studies in which the hypercoagulable role of PMVs has been demonstrated and associated with thrombosis-related conditions. The purpose of this review is to summarize what is currently known about PMVs and discuss whether a transfusion of isolated human PMVs could be used as a therapy for TIC.

Objectives: To test the hypothesis that nebulized epinephrine ameliorates pulmonary dysfunction by dual action—bronchodilation (β2-adrenergic receptor agonism) and attenuation of airway hyperemia (α1-adrenergic receptor agonism) with minimal systemic effects. Design: Randomized, controlled, prospective, and large animal translational studies. Setting: University large animal ICU. Subjects: Twelve chronically instrumented sheep. Interventions: The animals were exposed to 40% total body surface area third degree skin flame burn and 48 breaths of cooled cotton smoke inhalation under deep anesthesia and analgesia. The animals were then placed on a mechanical ventilator, fluid resuscitated, and monitored for 48 hours in a conscious state. After the injury, sheep were randomized into two groups: 1) epinephrine, nebulized with 4 mg of epinephrine every 4 hours starting 1 hour post injury, n = 6; or 2) saline, nebulized with saline in the same manner, n = 6. Measurements and Main Results: Treatment with epinephrine had a significant reduction of the pulmonary transvascular fluid flux to water (p < 0.001) and protein (p < 0.05) when compared with saline treatment from 12 to 48 hours and 36 to 48 hours, respectively. Treatment with epinephrine also reduced the systemic accumulation of body fluids (p < 0.001) with a mean of 1,410 ± 560 mL at 48 hours compared with 3,284 ± 422 mL of the saline group. Hemoglobin levels were comparable between the groups. Changes in respiratory system dynamic compliance, mean airway pressure, PaO₂/FiO₂ ratio, and oxygenation index were also attenuated with epinephrine treatment. No considerable systemic effects were observed with epinephrine treatment. Conclusions: Nebulized epinephrine should be considered for use in future clinical studies of patients with burns and smoke inhalation injury.