Effects of nebulized adipose-derived mesenchymal stem cells on acute lung injury following smoke inhalation in sheep.

INTRODUCTION: Treatment of ARDS caused by smoke inhalation is challenging with no specific therapies available. The aim of this study was to test the efficacy of nebulized adipose-derived mesenchymal stem cells (ASCs) in a well-characterized, clinically relevant ovine model of smoke inhalation injury. MATERIAL AND METHODS: Fourteen female Merino sheep were surgically instrumented 5-7 days prior to study. After induction of acute lung injury (ALI) by cooled cotton smoke insufflation into the lungs (under anesthesia and analgesia), sheep were placed on a mechanical ventilator for 48 hrs and monitored for cardiopulmonary hemodynamics in a conscious state. ASCs were isolated from ovine adipose tissue. Sheep were randomly allocated to two groups after smoke injury: 1) ASCs group (n = 6): 10 million ASCs were nebulized into the airway at 1 hr post-injury; and 2) Control group (n = 8): Nebulized with saline into the airways at 1 hr post-injury. ASCs were labeled with green fluorescent protein (GFP) to trace cells within the lung. ASCs viability was determined in bronchoalveolar lavage fluid (BALF). RESULTS: PaO2/FiO2 in the ASCs group was significantly higher than in the control group (p = 0.001) at 24 hrs. Oxygenation index: (mean airway pressure × FiO2/PaO2) was significantly lower in the ASCs group at 36 hr (p = 0.003). Pulmonary shunt fraction tended to be lower in the ASCs group as compared to the control group. GFP-labelled ASCs were found on the surface of trachea epithelium 48 hrs after injury. The viability of ASCs in BALF was significantly lower than those exposed to the control vehicle solution. CONCLUSION: Nebulized ASCs moderately improved pulmonary function and delayed the onset of ARDS.

Mesenchymal stem cell-derived exosomes for treatment of sepsis.

Introduction: The pathogenesis of sepsis is an imbalance between pro-inflammatory and anti-inflammatory responses. At the onset of sepsis, the lungs are severely affected, and the injury progresses to acute respiratory distress syndrome (ARDS), with a mortality rate of up to 40%. Currently, there is no effective treatment for sepsis. Cellular therapies using mesenchymal stem cells (MSCs) have been initiated in clinical trials for both ARDS and sepsis based on a wealth of pre-clinical data. However, there remains concern that MSCs may pose a tumor risk when administered to patients. Recent pre-clinical studies have demonstrated the beneficial effects of MSC-derived extracellular vesicles (EVs) for the treatment of acute lung injury (ALI) and sepsis. Methods: After recovery of initial surgical preparation, pneumonia/sepsis was induced in 14 adult female sheep by the instillation of Pseudomonas aeruginosa (~1.0×1011 CFU) into the lungs by bronchoscope under anesthesia and analgesia. After the injury, sheep were mechanically ventilated and continuously monitored for 24 h in a conscious state in an ICU setting. After the injury, sheep were randomly allocated into two groups: Control, septic sheep treated with vehicle, n=7; and Treatment, septic sheep treated with MSC-EVs, n=7. MSC-EVs infusions (4ml) were given intravenously one hour after the injury. Results: The infusion of MSCs-EVs was well tolerated without adverse events. PaO2/FiO2 ratio in the treatment group tended to be higher than the control from 6 to 21 h after the lung injury, with no significant differences between the groups. No significant differences were found between the two groups in other pulmonary functions. Although vasopressor requirement in the treatment group tended to be lower than in the control, the net fluid balance was similarly increased in both groups as the severity of sepsis progressed. The variables reflecting microvascular hyperpermeability were comparable in both groups. Conclusion: We have previously demonstrated the beneficial effects of bone marrow-derived MSCs (10×106 cells/kg) in the same model of sepsis. However, despite some improvement in pulmonary gas exchange, the present study demonstrated that EVs isolated from the same amount of bone marrow-derived MSCs failed to attenuate the severity of multiorgan dysfunctions.

The physiologic responses to a fluid bolus administration in old and young healthy adults.

BACKGROUND: Organ function is known to decline with age. Optimizing cardiac, pulmonary and renal function in older adults has led to significant improvements in perioperative care. However, when substantial blood loss and fluid shifts occur, perioperative outcomes still remains poor, especially in older adults. We suspect that this could be due to age-related changes in endothelial function-an organ controlling the transport of fluid and solutes. The capillary filtration coefficient (CFC) is an important determinant of fluid transport. The CFC can be measured in vivo, which provides a tool to estimate endothelial barrier function. We have previously shown that the CFC increases when giving a fluid bolus resulting in increased vascular and extravascular volume expansion, in young adults. This study aimed to compare the physiologic determinants of fluid distribution in young versus older adults so that clinicians can best optimize perioperative fluid therapy. METHODS: Ten healthy young volunteers (ages 21-35) and nine healthy older volunteers (ages 60-75) received a 10 mL/kg fluid bolus over the course of twenty minutes. Hemodynamics, systolic and diastolic heart function, fluid volumetrics and microcirculatory determinants were measured before, during, and after the fluid bolus. RESULTS: Diastolic function was reduced in older versus younger adults before and after fluid bolus (P < 0.01). Basal CFC and plasma oncotic pressure were lower in the older versus younger adults. Further, CFC did not increase in older adults following the fluid bolus, whereas it did in younger adults (p < 0.05). Cumulative urinary output, while lower in older adults, was not significantly different (p = 0.059). Mean arterial pressure and systemic vascular resistance were elevated in the older versus younger adults (p < 0.05). CONCLUSION: Older adults show a less reactive CFC to a fluid bolus, which could reduce blood to tissue transport of fluid. Diastolic dysfunction likely contributes to fluid maldistribution in older adults.

Mechanistic insights gained from cell and molecular analysis of the neuroprotective potential of bioactive natural compounds in an immortalized hippocampal cell line.

Evaluating novel compounds for neuroprotective effects in animal models of traumatic brain injury (TBI) is a protracted, labor-intensive and costly effort. However, the present lack of effective treatment options for TBI, despite decades of research, shows the critical need for alternative methods for screening new drug candidates with neuroprotective properties. Because natural products have been a leading source of new therapeutic agents for human diseases, we used an in vitro model of stretch injury to rapidly assess pro-survival effects of three bioactive compounds, two isolated from natural products (clovanemagnolol [CM], vinaxanthone [VX]) and the third, a dietary compound (pterostilbene [PT]) found in blueberries. The stretch injury experiments were not used to validate drug efficacy in a comprehensive manner but used primarily, as proof-of-principle, to demonstrate that the neuroprotective potential of each bioactive agent can be quickly assessed in an immortalized hippocampal cell line in lieu of comprehensive testing in animal models of TBI. To gain mechanistic insights into potential molecular mechanisms of neuroprotective effects, we performed a pathway-specific PCR array analysis of the effects of CM on the rat hippocampus and microRNA sequencing analysis of the effects of VX and PT on cultured hippocampal progenitor neurons. We show that the neuroprotective properties of these natural compounds are associated with altered expression of several genes or microRNAs that have functional roles in neurodegeneration or cell survival. Our approach could help in quickly assessing multiple natural products for neuroprotective properties and expedite the process of new drug discovery for TBI therapeutics.

Modulation of oxidative and nitrosative stress attenuates microvascular hyperpermeability in ovine model of Pseudomonas aeruginosa sepsis.

In sepsis, microvascular hyperpermeability caused by oxidative/nitrosative stress (O&NS) plays an important role in tissue edema leading to multi-organ dysfunctions and increased mortality. We hypothesized that a novel compound R-107, a modulator of O&NS, effectively ameliorates the severity of microvascular hyperpermeability and preserves multi-organ function in ovine sepsis model. Sepsis was induced in twenty-two adult female Merino sheep by intravenous infusion of Pseudomonas aeruginosa (PA) (1 × 1010 CFUs). The animals were allocated into: 1) Control (n = 13): intramuscular injection (IM) of saline; and 2) Treatment (n = 9): IM of 50 mg/kg R-107. The treatment was given after the PA injection, and monitored for 24-h. R-107 treatment significantly reduced fluid requirement (15-24 h, P < 0.05), net fluid balance (9-24 h, P < 0.05), and water content in lung/heart/kidney (P = 0.02/0.04/0.01) compared to control. R-107 treatment significantly decreased lung injury score/modified sheep SOFA score at 24-h (P = 0.01/0.04), significantly lowered arterial lactate (21-24 h, P < 0.05), shed syndecan-1 (3-6 h, P < 0.05), interleukin-6 (6-12 h, P < 0.05) levels in plasma, and significantly attenuated lung tissue 3-nitrotyrosine and vascular endothelial growth factor-A expressions (P = 0.03/0.002) compared to control. There was no adverse effect in R-107 treatment. In conclusion, modulation of O&NS by R-107 reduced hyperpermeability markers and improved multi-organ function.

Traumatic brain injury induces region-specific glutamate metabolism changes as measured by multiple mass spectrometry methods.

The release of excess glutamate following traumatic brain injury (TBI) results in glutamate excitotoxicity and metabolic energy failure. Endogenous mechanisms for reducing glutamate concentration in the brain parenchyma following TBI are poorly understood. Using multiple mass spectrometry approaches, we examined TBI-induced changes to glutamate metabolism. We present evidence that glutamate concentration can be reduced by glutamate oxidation via a "truncated" tricarboxylic acid cycle coupled to the urea cycle. This process reduces glutamate levels, generates carbon for energy metabolism, leads to citrulline accumulation, and produces nitric oxide. Several key metabolites are identified by metabolomics in support of this mechanism and the locations of these metabolites in the injured hemisphere are demonstrated by MALDI-MS imaging. The results of this study establish the advantages of multiple mass spectrometry approaches and provide insights into glutamate metabolism following TBI that could lead to improved treatment approaches.

Leveraging publicly available coronavirus data to identify new therapeutic targets for COVID-19.

Many important questions remain regarding severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the viral pathogen responsible for COVID-19. These questions include the mechanisms explaining the high percentage of asymptomatic but highly infectious individuals, the wide variability in disease susceptibility, and the mechanisms of long-lasting debilitating effects. Bioinformatic analysis of four coronavirus datasets representing previous outbreaks (SARS-CoV-1 and MERS-CoV), as well as SARS-CoV-2, revealed evidence of diverse host factors that appear to be coopted to facilitate virus-induced suppression of interferon-induced innate immunity, promotion of viral replication and subversion and/or evasion of antiviral immune surveillance. These host factors merit further study given their postulated roles in COVID-19-induced loss of smell and brain, heart, vascular, lung, liver, and gut dysfunction.

High molecular weight sodium hyaluronate improves survival of syndecan-1-deficient septic mice by inhibiting neutrophil migration.

METHODS: Sepsis was induced by cotton smoke inhalation followed by intranasal administration of Pseudomonas aeruginosa in female (> 6 months) Balb/c and syndecan-1 knockout mice. Survival of mice, lung capillary endothelial glycocalyx integrity, lung water content, and vascular hyper-permeability were determined with or without HMW-SH treatment in these mice. Effects of HMW-SH on endothelial permeability and neutrophil migration were tested in in vitro setting. RESULTS: In septic wildtype mice, we found a severely damaged pulmonary microvascular endothelial glycocalyx and elevated levels of shed syndecan-1 in the circulation. These changes were associated with significantly increased pulmonary vascular permeability. In septic syndecan-1 knockout mice, extravascular lung water content was higher, and early death was observed. The administration of HMW-SH significantly reduced mortality and lung water content in septic syndecan-1 knockout mice, but not in septic wildtype mice. In in vitro setting, HMW-SH inhibited neutrophil migration and reduced cultured endothelial cell permeability increases. However, these effects were reversed by the addition of recombinant syndecan-1 ectodomain. CONCLUSIONS: HMW-SH reduced lung tissue damage and mortality in the absence of syndecan-1 protein, possibly by reducing vascular hyper-permeability and neutrophil migration. Our results further suggest that increased shed syndecan-1 protein levels are linked with the inefficiency of HMW-SH in septic wildtype mice.

Omega-7 oil increases telomerase activity and accelerates healing of grafted burn and donor site wounds.

This study investigated the efficacy of Omega-7 isolated from the sea buckthorn oil (Polyvit Co., Ltd, Gangar Holding, Ulaanbaatar, Mongolia) in ovine burn wound healing models. In vitro, proliferation (colony-forming rate) and migration (scratch) assays using cultured primary ovine keratinocytes were performed with or without 0.025% and 0.08% Omega-7, respectively. The colony-forming rate of keratinocytes in the Omega-7 group at 72 and 96 h were significantly higher than in the control (P < 0.05). The percentage of closure in scratch assay in the Omega-7 group was significantly higher than in the control at 17 h (P < 0.05). In vivo, efficacy of 4% Omega-7 isolated from buckthorn oil was assessed at 7 and 14 days in grafted ovine burn and donor site wounds. Telomerase activity, keratinocyte growth factor, and wound nitrotyrosine levels were measured at day 14. Grafted sites: Un-epithelialized raw surface area was significantly lower and blood flow was significantly higher in the Omega-7-treated sites than in control sites at 7 and 14 days (P < 0.05). Telomerase activity and levels of keratinocyte growth factors were significantly higher in the Omega-7-treated sites after 14 days compared to those of control (P < 0.05). The wound 3-nitrotyrosine levels were significantly reduced by Omega-7. Donor sites: the complete epithelialization time was significantly shorter and blood flow at day 7 was significantly higher in the Omega-7-treated sites compared to control sites (P < 0.05). In summary, topical application of Omega-7 accelerates healing of both grafted burn and donor site wounds. Omega-7 should be considered as a cost-efficient and effective supplement therapy for burn wound healing.

Accelerated Failure Time Survival Model to Analyze Morris Water Maze Latency Data.

Traumatic brain injury (TBI) induces cognitive deficits clinically and in animal models. Learning and memory testing is critical when evaluating potential therapeutic strategies and treatments to manage the effects of TBI. We evaluated three data analysis methods for the Morris water maze (MWM), a learning and memory assessment widely used in the neurotrauma field, to determine which statistical tool is optimal for MWM data. Hidden platform spatial MWM data aggregated from three separate experiments from the same laboratory were analyzed using 1) a logistic regression model, 2) an analysis of variance (ANOVA) model, and 3) an accelerated failure time (AFT) time-to-event model. The logistic regression model showed no significant evidence of differences between treatments among any swims over all days of the study, p > 0.11. Although the ANOVA model found significant evidence of differences between sham and TBI groups on three out of four swims on the third day, results are potentially biased due to the failure of this model to account for censoring. The time-to-event AFT model showed significant differences between sham and TBI over all swims on the third day, p < 0.045, taking censoring into account. We suggest AFT models should be the preferred analytical methodology for latency to platform associated with MWM studies.

Arginine vasopressin receptor 2 activation promotes microvascular permeability in sepsis.

Methicillin-resistant Staphylococcus aureus (MRSA) sepsis is a severe condition associated with vascular leakage and poor prognosis. The hemodynamic management of sepsis targets hypotension, but there is no specific treatment available for vascular leakage. Arginine vasopressin (AVP) has been used in sepsis to promote vasoconstriction by activating AVP receptor 1 (V1R). However, recent evidence suggests that increased fluid retention may be associated with the AVP receptor 2 (V2R) activation worsening the outcome of sepsis. Hence, we hypothesized that the inhibition of V2R activation ameliorates the severity of microvascular hyperpermeability during sepsis. The hypothesis was tested using a well-characterized and clinically relevant ovine model of MRSA pneumonia/sepsis and in vitro assays of human lung microvascular endothelial cells (HMVECs). in vivo experiments demonstrated that the treatment of septic sheep with tolvaptan (TLVP), an FDA-approved V2R antagonist, significantly attenuated the sepsis-induced fluid retention and markedly reduced the lung water content. These pathological changes were not affected by the treatment with V2R agonist, desmopressin (DDAVP). Additionally, the incubation of cultured HMVECs with DDAVP, and DDAVP along with MRSA significantly increased the paracellular permeability. Finally, both the DDAVP and MRSA-induced hyperpermeability was significantly attenuated by TLVP. Subsequent protein and gene expression assays determined that the V2R-induced increase in permeability is mediated by phospholipase C beta (PLCß) and the potent permeability factor angiopoietin-2. In conclusion, our results indicate that the activation of the AVP-V2R axis is critical in the pathophysiology of severe microvascular hyperpermeability during Gram-positive sepsis. The use of the antagonist TLVP should be considered as adjuvant treatment for septic patients. The results from this clinically relevant animal study are highly translational to clinical practice.

Polyurethane foam for skin graft fixation in clinical-relevant ovine burn wound model for wound repair and regeneration research.

The availability of clinical-relevant large animal models for research in wound healing study is limited. Although a few reports described the wound dressing fixation method using polyurethane foam in patients, no animal studies were conducted to investigate efficacy of the polyurethane foam in grafted burn wounds. In the present study, we report a simple fixation method of grafted burned skin using polyurethane foam dressing (Allevyn Non-Adhesive, smith & nephew, UK) in a clinically relevant ovine grafted burn wound model. The dressing was removed at postoperative day 7 after skin graft. The grafted skin was completely engrafted without any complications. This method was safe and easy to perform and associated with good engraftment without any complications. We believe that the polyurethane foam fixation method may be successfully used in clinical practice as well as in preclinical studies for grafted burn wound repair and regeneration research.

Cutaneous burn diminishes beneficial effect of intravenously administered mesenchymal stem cells on acute lung injury induced by smoke inhalation in sheep.

OBJECTIVE: To investigate effects of intravenously administered allogeneic mesenchymal stem cells (MSCs) on burn/smoke-induced lung injury. METHODS: Sheep were subjected to 40%, third-degree flame skin burn and smoke inhalation under deep anesthesia and analgesia. One-hour after injury, PlasmaLite A (control) or 200 million MSCs (treatment) were intravenously administered. Pulmonary oxygenation index, PaO2/FiO2 ratio, lung-lymph flow, and bloodless lung wet-to-dry weight ratio were measured. Distribution of MSCs and stromal cell-derived factor-1 (Sdf-1) protein level were determined in lung and skin tissues. Effects of burn exudate on MSCs migration were characterized. RESULTS: MSCs did not attenuate pulmonary dysfunction. The number of MSCs was significantly higher in lungs of sheep with smoke inhalation compared with those with burn/smoke injury. In contrast, number of MSCs was significantly higher beneath burned skin in sheep with burn/smoke than in unburned skin of sheep with smoke inhalation only. Expression of Sdf-1 protein was increased in the burned skin compared to unburned skin. Effects of burn exudate on cultured MSCs proliferation differed depending on collection time. CONCLUSION: Skin burn diminishes beneficial effects of MSCs on smoke-induced lung injury, by promoting migration of MSCs from the pulmonary tissue to the injured skin area, possibly via expression of Sdf-1 protein.

Principal component analysis of blood microRNA datasets facilitates diagnosis of diverse diseases.

Early, ideally pre-symptomatic, recognition of common diseases (e.g., heart disease, cancer, diabetes, Alzheimer's disease) facilitates early treatment or lifestyle modifications, such as diet and exercise. Sensitive, specific identification of diseases using blood samples would facilitate early recognition. We explored the potential of disease identification in high dimensional blood microRNA (miRNA) datasets using a powerful data reduction method: principal component analysis (PCA). Using Qlucore Omics Explorer (QOE), a dynamic, interactive visualization-guided bioinformatics program with a built-in statistical platform, we analyzed publicly available blood miRNA datasets from the Gene Expression Omnibus (GEO) maintained at the National Center for Biotechnology Information at the National Institutes of Health (NIH). The miRNA expression profiles were generated from real time PCR arrays, microarrays or next generation sequencing of biologic materials (e.g., blood, serum or blood components such as platelets). PCA identified the top three principal components that distinguished cohorts of patients with specific diseases (e.g., heart disease, stroke, hypertension, sepsis, diabetes, specific types of cancer, HIV, hemophilia, subtypes of meningitis, multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer's disease, mild cognitive impairment, aging, and autism), from healthy subjects. Literature searches verified the functional relevance of the discriminating miRNAs. Our goal is to assemble PCA and heatmap analyses of existing and future blood miRNA datasets into a clinical reference database to facilitate the diagnosis of diseases using routine blood draws.

Superior Effects of Nebulized Epinephrine to Nebulized Albuterol and Phenylephrine in Burn and Smoke Inhalation-Induced Acute Lung Injury.

The severity of burn and smoke inhalation-induced acute lung injury (BSI-ALI) is associated with alveolar and interstitial edema, bronchospasm, and airway mucosal hyperemia. Previously, we have reported beneficial effects of epinephrine nebulization on BSI-ALI. However, the underlying mechanisms of salutary effects of nebulized epinephrine remain unclear. The present study compared the effects of epinephrine, phenylephrine, and albuterol on a model of BSI-ALI. We tested the hypothesis that both α1- and ß2-agonist effects are required for ameliorating more efficiently the BSI-ALI. Forty percent of total body surface area, 3rd-degree cutaneous burn, and 48-breaths of cotton smoke inhalation were induced to 46 female Merino sheep. Postinjury, sheep were mechanically ventilated and cardiopulmonary hemodynamics were monitored for 48 h. Sheep were allocated into groups: control, n = 17; epinephrine, n = 11; phenylephrine, n = 6; and albuterol, n = 12. The drug nebulization began 1 h postinjury and was repeated every 4 h thereafter. In the results, epinephrine group significantly improved oxygenation compared to other groups, and significantly reduced pulmonary vascular permeability index, lung wet-to-dry weight ratio, and lung tissue growth factor-ß1 level compared with albuterol and control groups. Epinephrine and phenylephrine groups significantly reduced trachea wet-to-dry weight ratio and lung vascular endothelial growth factor-A level compared with control group. Histopathologically, epinephrine group significantly reduced lung severity scores and preserved vascular endothelial-cadherin level in pulmonary arteries. In conclusion, the results of our studies suggest that nebulized epinephrine more effectively ameliorated the severity of BSI-ALI than albuterol or phenylephrine, possibly by its combined α1- and ß2-agonist properties.

The Clinical Presentation and Immunology of Viral Pneumonia and Implications for Management of Coronavirus Disease 2019.

This review will briefly examine the clinical presentation and important immunology of viral pneumonia with a focus on severe acute respiratory syndrome coronavirus 2 (coronavirus disease 2019). DATA SOURCES STUDY SELECTION DATA EXTRACTION AND DATA SYNTHESIS: The most relevant, original and review literature were assessed for inclusion in this review. Sources included the Centers for Disease Control and Prevention, World Health Organization, and PubMed. CONCLUSIONS: Pneumonia is a leading cause of hospitalization and death worldwide, with viral etiologies being very common. Given the rapidly emerging pandemic associated with the novel severe acute respiratory syndrome coronavirus 2 causing coronavirus disease 2019, it is important to review the clinical presentation and immunologic changes associated with viral pneumonia. Symptoms of viral pneumonia include common respiratory tract infection symptoms of cough, fever, and shortness of breath. Immunologic changes include up-regulation of airway pro-inflammatory cytokines and pathogen- and damage-associated molecular patterns contributing to cytokine and genomic changes. Coronavirus disease 2019 clinical presentation is typical of viral pneumonia with an increased prevalence of early pulmonary infiltrates and lymphopenia. Principles of early coronavirus disease 2019 management and isolation as well as potential therapeutic approaches to the emerging pandemic are discussed.

Adipose-derived stem cells improve grafted burn wound healing by promoting wound bed blood flow.

BACKGROUND: Researchers have explored the use of adipose-derived stem cells (ASCs) as a cell-based therapy to cover wounds in burn patients; however, underlying mechanistic aspects are not completely understood. We hypothesized that ASCs would improve post-burn wound healing after eschar excision and grafting by increasing wound blood flow via induction of angiogenesis-related pathways. METHODS: To test the hypothesis, we used an ovine burn model. A 5 cm2 full thickness burn wound was induced on each side of the dorsum. After 24 hours, the burned skin was excised and a 2 cm2 patch of autologous donor skin was grafted. The wound sites were randomly allocated to either topical application of 7 million allogeneic ASCs or placebo treatment (phosphate-buffered saline [PBS]). Effects of ASCs culture media was also compared to those of PBS. Wound healing was assessed at one and two weeks following the application of ASCs. Allogeneic ASCs were isolated, cultured and characterized from non-injured healthy sheep. The identity of the ASCs was confirmed by flow cytometry analysis, differentiation into multiple lineages and gene expression via real-time polymerase chain reaction. Wound blood flow, epithelialization, graft size and take and the expression of vascular endothelial growth factor (VEGF) were determined via enzyme-linked immunosorbent assay and Western blot. RESULTS: Treatment with ASCs accelerated the patch graft growth compared to the control (p < 0.05). Topical application of ASCs significantly increased wound blood flow (p < 0.05). Expression of VEGF was significantly higher in the wounds treated with ASCs compared to control (p < 0.05). CONCLUSIONS: ASCs accelerated grafted skin growth possibly by increasing the blood flow via angiogenesis induced by a VEGF-dependent pathway.

Blood carboxyhemoglobin elimination curve, half-lifetime, and arterial-venous differences in acute phase of carbon monoxide poisoning in ovine smoke inhalation injury model.

Smoke inhalation injury (SII) affects more than 50,000 people annually causing carbon monoxide (CO) poisoning. Although the increased blood level of carboxyhemoglobin (CO-Hb) is frequently used to confirm the diagnosis of SII, knowledge of its elimination in the acute phase is still limited. The aim of this study is to determine CO-Hb elimination rates and their differences in arterial (aCO-Hb) and mixed-venous (vCO-Hb) blood following severe SII in a clinically relevant ovine model. Forty-three chronically instrumented female sheep were subjected to SII (12 breaths, 4 sets) through tracheostomy tube under anesthesia and analgesia. After the SII, sheep were awakened and placed on a mechanical ventilator (FiO2 = 1.0, tidal volume 12 mL/kg, and PEEP = 5cmH2O) and monitored. Arterial and mixed-venous blood samples were withdrawn simultaneously for blood gas analysis at various time points to determine CO-HB half-lifetime and an elimination curve. The mean of highest aCO-Hb level during SII was 70.8 ± 13.9%. The aCO-Hb elimination curve showed an approximated exponential decay during the first 60 min. Per mixed linear regression model analysis, aCO-Hb significantly (p < 0.001) declined (4.3%/minute) with a decay constant lambda of 0.044. With this lambda, mean lifetime and half-lifetime of aCO-Hb were 22.7 and 15.7 min, respectively. The aCO-Hb was significantly lower compared to vCO-Hb at all-time points (0-180 min). To our knowledge, this is the first report describing CO-Hb elimination curve in the acute phase after severe SII in the clinically relevant ovine model. Our data shows that CO-Hb is decreasing in linear manner with supportive mechanical ventilation (0-60 min). The results may help to understand CO-Hb elimination curve in the acute phase and improvement of pre-hospital and initial clinical care in patients with CO poisoning.