Pilot study of frozen platelet extracellular vesicles as a therapeutic agent in hemorrhagic shock in rats

BACKGROUND

Hemorrhage accounts for the most preventable deaths after trauma. Resuscitation is guided by studies that demonstrate improved outcomes in patients receiving whole blood or balanced administration of blood products. Platelets present a logistical challenge due to short shelf life and need for refrigeration. Platelet-derived extracellular vesicles (PEVs) are a possible platelet alternative. Platelet-derived extracellular vesicles are secreted from platelets, have hemostatic effects and mitigate inflammation and vascular injury, similar to platelets. This pilot study aimed to elucidate the therapeutic effects of PEVs in a rat model of uncontrolled hemorrhage.

METHODS

Male rats were anesthetized and femoral vessels cannulated. Vital signs (MAP, HR, and RR) were monitored. Electrolytes, lactate and ABG were obtained at baseline, 1-hour and 3-hours post injury. Laparotomy was performed, 50% of the middle hepatic lobe excised and the abdomen packed with gauze. Rats received 2 mL PEVs or lactated Ringers (LR) over 6 minutes immediately after injury. Peritoneal blood loss was quantified using preweighed gauze at 5 minutes, 15 minutes, 30 minutes, 45 minutes, and 60 minutes. Laparotomy was closed 1-hour postinjury. Animals were monitored for 3 hours postinjury then euthanized. Generalized Linear Mixed Effects models were performed to assess effects of treatment and time on lactate and MAP.

RESULTS

Twenty-one rats were included (11 LR, 10 PEV). Overall blood loss was between 6 mL and 10 mL and not significantly different between groups. There was a 36% mortality rate in the LR group and 0% mortality in the PEV group ( p = 0.03). The LR group had significantly higher lactates at 1 hour ( p = 0.025). At 15 minutes, 45 minutes, 60 minutes, and 180 minutes, the MAP of the PEV group was significantly higher than the LR group.

CONCLUSION

Early studies are encouraging regarding the potential use of PEVs in uncontrolled hemorrhagic shock based on improved survival and hemodynamics.

Association of fibrinolysis phenotype with patient outcomes following traumatic brain injury

BACKGROUND

Impaired coagulation is associated with elevated risk of mortality in trauma patients. Prior studies have demonstrated increased mortality in patients with hyperfibrinolysis (HF) and fibrinolysis shutdown (SD). In addition, prior studies have demonstrated no effect of tranexamic acid (TXA) on fibrinolysis phenotypes. We examined the association of admission fibrinolysis phenotype with traumatic brain injury (TBI) patient outcomes.

METHODS

Data were extracted from a placebo-controlled multicenter clinical trial. Patients ≥15 years with TBI (Glasgow Coma Scale score, 3-12) and systolic blood pressure ≥90 mm Hg were randomized in the out-of-hospital setting to receive placebo bolus/placebo infusion (Placebo), 1 gram (g) TXA bolus/1 g TXA infusion (bolus maintenance [BM]); or 2 g TXA bolus/placebo infusion (bolus only [BO]). Fibrinolysis phenotypes on admission were determined by clot lysis at 30 minutes (LY30): SD, ≤0.8%; physiologic, 0.9% to 2.9%; HF, ≥3%. Logistic regression was used to control for age, sex, penetrating injury, Injury Severity Score, maximum head AIS, and TXA treatment group.

RESULTS

Seven hundred forty-seven patients met inclusion criteria. Fibrinolysis shutdown was the most common phenotype in all treatment groups and was associated with increased age, Injury Severity Score, and presence of intracranial hemorrhage (ICH). Inpatient mortality was 15.2% for SD and HF, and 10.6% for physiologic ( p = 0.49). No differences in mortality, disability rating scale at 6 months, acute kidney injury, acute respiratory distress syndrome, or multi-organ failure were noted between fibrinolysis phenotypes.

CONCLUSION

SD is the most common phenotype expressed in moderate to severe TBI. In TBI, there is no association between fibrinolysis phenotype and mortality or other major complications.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level IV.

Emergency department thoracotomy in children: A Pediatric Trauma Society, Western Trauma Association, and Eastern Association for the Surgery of Trauma systematic review and practice management guideline

BACKGROUND

The role of emergency department resuscitative thoracotomy (EDT) in traumatically injured children has not been elucidated. We aimed to perform a systematic review and create evidence-based guidelines to answer the following PICO (population, intervention, comparator, and outcome) question: should pediatric patients who present to the emergency department pulseless (with or without signs of life [SOL]) after traumatic injuries (penetrating thoracic, penetrating abdominopelvic, or blunt) undergo EDT (vs. no EDT) to improve survival and neurologically intact survival?

METHODS

Using Grading of Recommendations Assessment, Development and Evaluation methodology, a group of 12 pediatric trauma experts from the Pediatric Trauma Society, Western Trauma Association, and Eastern Association for the Surgery of Trauma assembled to perform a systematic review. A consensus conference was conducted, a database was queried, abstracts and manuscripts were reviewed, data extraction was performed, and evidence quality was determined. Evidence tables were generated, and the committee voted on guideline recommendations.

RESULTS

Three hundred three articles were identified. Eleven studies met the inclusion criteria and were used for guideline creation, providing 319 pediatric patients who underwent EDT. No data were available on patients who did not undergo EDT. For each PICO, the quality of evidence was very low based on the serious risk of bias and serious or very serious imprecision.

CONCLUSION

Based on low-quality data, we make the following recommendations. We conditionally recommend EDT when a child presents pulseless with SOL to the emergency department following penetrating thoracic injury, penetrating abdominopelvic injury and after blunt injury if emergency adjuncts point to a thoracic source. We conditionally recommend against EDT when a pediatric patient presents pulseless without SOL after penetrating thoracic and penetrating abdominopelvic injury. We strongly recommend against EDT in the patient without SOL after blunt injury.

Measurement Properties of Social Communication Assessments for Transition-Age Adolescents: A Systematic Review

Purpose An important role of social communication assessment is to support intervention planning as adolescents with disabilities transition to workplaces and other adult settings. Adoption of evidence-based assessment practices would align professionals with legal and ethical mandates for schools and other settings. There is, however, limited adoption of evidence-based assessment selection. The COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) provide a structured approach to identifying assessments with sufficient validity and reliability backed by strong evidence. The purpose of this review was to identify directly administered social communication assessments for adolescents and to apply the COSMIN framework to evaluate their measurement properties. Method A systematic search identified 13 assessments designed for 14- to 21-year-olds with developmental disabilities putting them at risk for social communication deficits. Measurement properties were extracted from included studies and rated for sufficiency. The quality of evidence supporting the findings was graded using COSMIN guidelines. Results Five social communication assessments were recommended as having sufficient evidence of content validity and internal consistency. Remaining assessments could be recommended as gaps in the evidence for their measurement properties are filled. Conclusions The application of the COSMIN standards has the potential to advance evidence-based assessment for social communication. There were important gaps in the independent replication of measurement properties and methodological shortcomings in the evaluation of reliability, measurement error, and structural validity.

Abstract A37: CTLA-4 blockade improves the balance of CD8+ effector and CD4+ regulatory T cells following adoptive cell transfer melanoma immunotherapy

Background: Clinical trials have shown efficacy for CTLA-4 blockade and adoptive cell transfer (ACT) immunotherapy in the treatment of melanoma. We hypothesized that the addition of CTLA-4 blockade to a non-lymphodepleting regimen of ACT could enhance the control of melanoma tumor growth in a murine model.

Methods: A B16F10 melanoma cell line was stably transfected to express low levels of the lymphocytic choriomeningitis virus (LCMV) peptide GP33 (B16GP33). Immunocompetent Ly5.2+/C57BL/6 mice were inoculated with subcutaneous flank injections of 106 B16GP33 cells on day 0. GP33-specific CD8+ T cells were harvested from syngeneic Ly5.1+/C57BL/6 donor mice 8 days after LCMV infection. Mice received no treatment, CTLA-4 blockade (intraperitoneal injections of 200 μg anti-CTLA-4 mAb on days 2, 5, and 8), ACT (intravenous injections of 5x104 GP33-specific CD8+ T cells on day 1), or both. Tumor growth was measured every three days. Subsets of mice were euthanized between days 9 and 18 for TIL and splenocyte analyses. Mice exhibiting minimal B16GP33 tumor growth > 30 days after immunotherapy were challenged with contralateral flank injections of 106 B16F10 and B16GP33 cells.

Results: Combination CTLA-4 blockade and ACT immunotherapy resulted in significantly greater inhibition of B16GP33 tumor growth compared to CTLA-4 blockade or ACT alone. TIL analysis identified stronger CD8+ T cell infiltration in tumors treated with combination immunotherapy. This augmented TIL response was due to the induction of endogenous populations of CD8+ T cells, as there were no differences in Ly5.1+/CD8+ T cell infiltration between mice treated with combination immunotherapy versus ACT alone. Significantly fewer CD4+CD25+FoxP3+ regulatory T cells were observed within TIL populations after combination immunotherapy. Splenocyte response to in vitro stimulation with GP33 peptide was stronger after combination immunotherapy compared to single agent immunotherapy. A subset of mice treated with CTLA-4 blockade alone and combination immunotherapy showed minimal B16GP33 tumor growth after prolonged observation. Both groups of mice showed immunity against B16GP33 challenge tumors, but only mice treated with combination immunotherapy exhibited immunity against B16F10 challenge tumors as well.

Discussion: The combination of CTLA-4 blockade with non-lymphodepletion ACT may represent a novel and effective form of melanoma immunotherapy. Our findings suggest that the additive benefit of CTLA-4 may be due to the enhanced recruitment of endogenous melanoma-directed effector T cell responses and the induction of smaller populations of regulatory T cells. Moreover, the promotion of a durable and generalized protection from recurrent tumors suggests that this combination may have synergistic immunological effects against melanoma.

Citation Format: Lucy Wentworth, David A. Mahvi, Justin V. Meyers, Samantha Durbin, Clifford S. Cho. CTLA-4 blockade improves the balance of CD8+ effector and CD4+ regulatory T cells following adoptive cell transfer melanoma immunotherapy. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr A37.

Ticlopidine increases nitric oxide generation in heart-transplant recipients: a possible novel property of ticlopidine

The objective of this study was to evaluate the effects of ticlopidine on the generation of eicosanoids and nitric oxide in heart-transplant recipients. In a randomized double-blind study, we studied the urinary excretion of the stable metabolites of thromboxane, prostacyclin, and nitric oxide before and after ticlopidine (250 mg/day). Platelet aggregation was significantly reduced in ticlopidine-treated patients [from 40.2 +/- 24.2% of maximal aggregation to 14.7 +/- 8.2% in response to adenosine diphosphate (ADP); p < 0.001] but not in the placebo group, confirming the efficacy of the drug with that dosage in these specific patients. The 24-h urinary excretion of prostacyclin metabolites was not modified by ticlopidine (1,865 +/- 833 ng/24 h at day 14 and 1,664 +/- 425 ng/24 h at day 0), whereas the excretion of thromboxane B2 tended to increase in the ticlopidine group (from 3,854 +/- 1,163 ng/24 h at day 0 to 5,014 +/- 2,914 ng/24 h at day 14), although not significantly. The excretion of nitric oxide metabolites (although not different from that of healthy nonimmunosuppressed subjects) was significantly (p < 0.005) increased in the ticlopidine group (from 3,082 +/- 1,683 micromol/24 h at day 0 to 4,133 +/- 2,262 micromol/24 h at day 14), but not in controls. Thus ticlopidine does not reduce prostacyclin but increases the systemic generation of nitric oxide, both substances having major antiplatelet and vasodilator properties. Further studies are warranted to examine whether ticlopidine could reduce the incidence of thromboembolic complications in these patients and whether this possible novel property of ticlopidine is restricted to immunosuppressed heart-transplant recipients.

Integrating strategic planning and quality management in a multi-institutional system

Integrating total quality management (TQM) into the strategic planning process of a multi-institutional health system is a high priority. Through the strategic plan, system leadership gives TQM concepts prominence and visibility and provides strategic directions for their implementation. The Sisters of Providence Health System recently developed an approach to integrating TQM into its System Strategic Plan. Implementation priorities include more formalized direction for TQM by the system board, intensive TQM educational programs, greater consistency of quality information and outcome measures, and more focused attention to patient needs.

Regional changes in central nervous system thyrotropin-releasing hormone after pentylenetetrazol-induced seizures in dogs

We have recently shown that seizures induce significant and sustained elevations of thyrotropin-releasing hormone (TRH) in specific extrahypothalamic rat brain regions associated with epileptic foci including amygdala, hippocampus, pyriform cortex, and anterior cortex. Seizures were induced in dogs to further study the effect on central nervous system TRH in a species known to show epileptiform seizures. Adult mongrel beagles were given pentylenetetrazol (PTZ) to induce generalized tonic-clonic seizures. Two groups of dogs were given either PTZ or saline every other day for four intravenous injections. Major motor seizures were observed visually and by electroencephalography with each PTZ injection, and these lasted from 3 to 10 minutes. Forty-eight hours after the fourth seizure, the dogs were killed and brains were removed, dissected, and stored at -90 degrees. After acetic acid extraction, extracts were assayed for TRH content by specific radioimmunoassay. Significant (P < 0.05) postictal TRH increases were seen in frontal cortex (1.5-fold), dorsal hippocampus (2.2-fold), pyriform cortex (2.5-fold), and amygdala (2.1-fold). Cerebellum, medulla, thalamus, hypothalamus, and septum showed no postictal changes in TRH. This report is the first to demonstrate TRH elevations in specific central nervous system regions associated with epileptic foci in the dog. Our results continue to stress the importance of the pyriform/periamygdaloid region as a key limbic region of endogenous TRH action in response to seizures and provides further evidence that TRH is either directly or indirectly involved in seizure modulation. Additional recent data from our laboratory and others suggest that this modulation is intrinsic to the hippocampus and may be anticonvulsant in nature.