A comparative study of a preclinical survival model of smoke inhalation injury in mice and rats.

Smoke inhalation injury increases morbidity and mortality. Clinically relevant animal models are necessary for the continued investigation of the pathophysiology of inhalation injury and the development of therapeutics. The goal of our research was threefold: 1) to develop a reproducible survival model of smoke inhalation injury in rats that closely resembled our previous mouse model, 2) to validate the rat smoke inhalation injury model using a variety of laboratory techniques, and 3) to compare and contrast our rat model with both the well-established mouse model and previously published rat models to highlight our improvements on smoke delivery and lung injury. Mice and rats were anesthetized, intubated, and placed in custom-built smoke chambers to passively inhale woodchip-generated smoke. Bronchoalveolar lavage fluid (BALF) and lung tissue were collected for confirmatory tests. Lung sections were hematoxylin and eosin stained, lung edema was assessed with wet-to-dry (W/D) ratio, and inflammatory cell infiltration and cytokine elevation were evaluated using flow cytometry, immunohistochemistry, and ELISA. We confirmed that our mouse and rat models of smoke inhalation injury mimic the injury seen after human burn inhalation injury with evidence of pulmonary edema, neutrophil infiltration, and inflammatory cytokine elevation. Interestingly, rats mounted a more severe immunological response compared with mice. In summary, we successfully validated a reliable and clinically translatable survival model of lung injury and immune response in rats and mice and characterized the extent of this injury. These animal models allow for the continued study of smoke inhalation pathophysiology to ultimately develop a better therapeutic.

Emerging therapies for smoke inhalation injury: a review.

BACKGROUND: Smoke inhalation injury increases overall burn mortality by up to 20 times. Current therapy remains supportive with a failure to identify an optimal or targeted treatment protocol for smoke inhalation injury. The goal of this review is to describe emerging therapies that are being developed to treat the pulmonary pathology induced by smoke inhalation injury with or without concurrent burn injury. MAIN BODY: A comprehensive literature search was performed using PubMed (1995-present) for therapies not approved by the U.S. Food and Drug Administration (FDA) for smoke inhalation injury with or without concurrent burn injury. Therapies were divided based on therapeutic strategy. Models included inhalation alone with or without concurrent burn injury. Specific animal model, mechanism of action of medication, route of administration, therapeutic benefit, safety, mortality benefit, and efficacy were reviewed. Multiple potential therapies for smoke inhalation injury with or without burn injury are currently under investigation. These include stem cell therapy, anticoagulation therapy, selectin inhibition, inflammatory pathway modulation, superoxide and peroxynitrite decomposition, selective nitric oxide synthase inhibition, hydrogen sulfide, HMG-CoA reductase inhibition, proton pump inhibition, and targeted nanotherapies. While each of these approaches shows a potential therapeutic benefit to treating inhalation injury in animal models, further research including mortality benefit is needed to ensure safety and efficacy in humans. CONCLUSIONS: Multiple novel therapies currently under active investigation to treat smoke inhalation injury show promising results. Much research remains to be conducted before these emerging therapies can be translated to the clinical arena.

Sex bias persists in surgical research: A 5-year follow-up study.

BACKGROUND: Federal initiatives have recently addressed the sex bias that exists in biomedical and clinical research. However, improvement to the inclusion of sex as a biological variable remains unknown. METHODS: We performed a 5-year follow-up study of all clinical and biomedical research articles published in 5 surgical journals from January 1, 2017, through December 31, 2018. Human, animal, and cell subjects were analyzed for study/subject type, sex of participants, sex matching, and sex-based data reporting, analysis, and discussion. RESULTS: Comparing 2017 to 2018 with 2011 to 2012, slightly more articles reported the sex of the human studied (87% vs 83%; P = .001). Inclusion of both sexes remained high (94% vs 95%; P = .22), but sex-based data reporting (36% vs 38%; P = .17), analysis (35% vs 33%; P = .39), and discussion of results (10% vs 23%; P < .0001) remained unchanged or worsened. Regarding animal research, the number of articles that stated the sex studied remained unchanged (79% vs 78%; P = .67); if stated, slightly more included both sexes (7% vs 3%; P = .002). Regarding cell research, fewer articles reported the sex of the cells studied (5% vs 24%; P = .0001); if stated, more articles included both sexes, but the difference did not reach statistical significance (25% vs 7%; P = .34). Sex matching remained poor with only 50% of human, 4% of animal, and 9% of cell studies matching the inclusion of both sexes by at least 50%. CONCLUSION: Sex bias persists in surgical research. The majority of articles failed to report, analyze, or discuss results based on sex, which will negatively affect clinical translatability and outcomes of evidence-based medicine.

Development of novel nanofibers targeted to smoke-injured lungs.

Smoke inhalation injury is associated with significant mortality and current therapies remain supportive. The purpose of our study was to identify proteins upregulated in the lung after smoke inhalation injury and develop peptide amphiphile nanofibers that target these proteins. We hypothesize that nanofibers targeted to angiotensin-converting enzyme or receptor for advanced glycation end products will localize to smoke-injured lungs. METHODS: Five targeting sequences were incorporated into peptide amphiphile monomers methodically to optimize nanofiber formation. Nanofiber formation was assessed by conventional transmission electron microscopy. Rats received 8 min of wood smoke. Levels of angiotensin-converting enzyme and receptor for advanced glycation end products were evaluated by immunofluorescence. Rats received the targeted nanofiber 23 h after injury via tail vein injection. Nanofiber localization was determined by fluorescence quantification. RESULTS: Peptide amphiphile purity (>95%) and nanofiber formation were confirmed. Target proteins were increased in smoke inhalation versus sham (p < 0.001). After smoke inhalation and injection of targeted nanofibers, we found a 10-fold increase in angiotensin-converting enzyme-targeted nanofiber localization to lung (p < 0.001) versus sham with minimal localization of non-targeted nanofiber (p < 0.001). CONCLUSIONS: We synthesized, characterized, and evaluated systemically delivered targeted nanofibers that localized to the site of smoke inhalation injury in vivo. Angiotensin-converting enzyme-targeted nanofibers serve as the foundation for developing a novel nanotherapeutic that treats smoke inhalation lung injury.

Intravenous Delivery of Lung-Targeted Nanofibers for Pulmonary Hypertension in Mice.

Pulmonary hypertension is a highly morbid disease with no cure. Available treatments are limited by systemic adverse effects due to non-specific biodistribution. Self-assembled peptide amphiphile (PA) nanofibers are biocompatible nanomaterials that can be modified to recognize specific biological markers to provide targeted drug delivery and reduce off-target toxicity. Here, PA nanofibers that target the angiotensin I-converting enzyme and the receptor for advanced glycation end-products (RAGE) are developed, as both proteins are overexpressed in the lung with pulmonary hypertension. It is demonstrated that intravenous delivery of RAGE-targeted nanofibers containing the targeting epitope LVFFAED (LVFF) significantly accumulated within the lung in a chronic hypoxia-induced pulmonary hypertension mouse model. Using 3D light sheet fluorescence microscopy, it is shown that LVFF nanofiber localization is specific to the diseased pulmonary tissue with immunofluorescence analysis demonstrating colocalization of the targeted nanofiber to RAGE in the hypoxic lung. Furthermore, biodistribution studies show that significantly more LVFF nanofibers localized to the lung compared to major off-target organs. Targeted nanofibers are retained within the pulmonary tissue for 24 h after injection. Collectively, these data demonstrate the potential of a RAGE-targeted nanomaterial as a drug delivery platform to treat pulmonary hypertension.

Alternative payment models: can (should) trauma care be bundled?

BACKGROUND: Recent legislation repealing the Sustainable Growth Rate mandates gradual replacement of fee for service with alternative payment models (APMs), which will include service bundling. We analyzed the 2 years' experience at our state-designated level I trauma center to determine the feasibility of such an approach for trauma care. METHODS: De-identified data from all injured patients treated by the trauma service during 2014 and 2015 were reviewed to determine individual patient injury profiles. Using these injury profiles we created the 'trauma bundle' by concatenating the highest Abbreviated Injury Scale score for each of the six body regions to produce a single 'signature' of injury by region for every patient. These trauma bundles were analyzed by frequency over 2 years and by each year. The impacts of physiology and resource consumption were evaluated by determination of the correlation of the mean and SD of calculated survival probability (Ps) and intensive care unit length of stay (ICU LOS) for each profile group occurring more than 12 times in 2 years. RESULTS: The 5813 patients treated over 2 years produced 858 distinct injury profiles, only 8% (71) of which occurred more than 12 times in 2 years. Comparison of 2014 and 2015 profiles demonstrated high frequency variation among profiles between the 2 years. Analysis of injury patterns occurring >12 times in 2 years demonstrated an inverse correlation between the mean and SD for Ps (R2=0.68) and a direct correlation for ICU LOS (R2=0.84). DISCUSSION: These data indicate that the disease of injury is too inconsistent a mix of injury pattern and physiologic response to be predictably bundled for an APM. The inverse correlation of increasing SD with increasing ICU LOS and decreasing Ps suggests an opportunity for measurable process improvement. LEVEL OF EVIDENCE: Economic and value-based evaluations, level IV. STUDY TYPE: Economic/decision.