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Sznitman, J.

Publications and source records attributed to Sznitman, J..

4 recordsLinked to original sources

iPSCs-derived Bronchial Airways-On-Chip for Assessment of Cytokine Secretion triggered by Volatile Organic Compounds

Air quality monitoring currently relies mostly on a combination of epidemiological data and classic experimental data. Our objective was to design an alternative approach for assessing air pollutant risk potential using a specialized platform capable of detecting long-term and indirect effects of exposure via the inhaled route. We used a Bronchial Airways-On-Chip (BOC) offering some of the physiological complexity of the human lung based on our previously developed device coupled with in-vitro differentiated bronchial epithelium derived from induced Pluripotent Stem Cells (iPSCs). This setup is capable of replicating bronchial epithelia exposure to irritants at air-liquid interface, in controlled and reproducible conditions. It comprises the first proof-of-concept design combining a BOC with iPSCs-derived bronchial epithelium as an alternative approach towards potential risk assessmnet of inhaled pollutants. As a representative pollutant we use Benzene, a Volatile Organic Compound (VOC). At low concentrations and short-term exposure it is not considered acutely harmful, but long-term exposure can result in mutagenic and carcinogenic effects. As air pollutant toxicity is known to be mediated by the respiratory epithelial lining and secretion of cytokines, we demonstrate our system to be sufficiently sensitive to capture increased cytokine secretion corresponding to increasing concentrations of Benzene. Of utmost relevance is our finding that an accumulative effect could be detected, only caused by prolonged exposure at low concentrations of Benzene, previously shown to be non-toxic in classic short-term in-vitro studies. Finally, the accumulative effect could be reversed using a commonly-used asthma medication (Montelukast), further supporting the relevance of the setup.

bioengineering↗

In vitro-in silico correlation of three-dimensional turbulent flows in an idealized mouth-throat model

There exists an ongoing need to improve the validity and accuracy of computational fluid dynamics (CFD) simulations of turbulent airflows in the extra-thoracic and upper airways. Yet, a knowledge gap remains in providing experimentally-resolved 3D flow benchmarks with sufficient data density and completeness for useful comparison with widely-employed numerical schemes. Motivated by such shortcomings, the present work details to the best of our knowledge the first attempt to deliver in vitro-in silico correlations of 3D respiratory airflows in a generalized mouth-throat model and thereby assess the performance of Large Eddy Simulations (LES) and Reynolds-Averaged Numerical Simulations (RANS). Numerical predictions are compared against 3D volumetric flow measurements using Tomographic Particle Image Velocimetry (TPIV) at three steady inhalation flowrates varying from shallow to deep inhalation conditions. We find that a RANS k-{omega} SST model adequately predicts velocity flow patterns for Reynolds numbers spanning 1500 to 7000, supporting results in close proximity to a more computationally-expensive LES model. Yet, RANS significantly underestimates turbulent kinetic energy (TKE), thus underlining the advantages of LES as a higher-order turbulence modeling scheme. In an effort to bridge future endevours across respiratory research disciplines, we provide end users with the present in vitro -in silico correlation data for improved predictive CFD models towards inhalation therapy and therapeutic or toxic dosimetry endpoints. Author SummaryThe dispersion and ensuing deposition of inhaled airborne particulate matter in the lungs are strongly influenced by the dynamics of turbulent respiratory airflows in the mouth-throat region during inhalation. To cirumvent costly in vitro experimental measurement resources, fluid dynamics (CFD) simulations are widely sought to predict deposition outcomes but often lack detailed experimental data to first validate the three-dimensional (3D) flow structures anticipated to arise in the upper respiratory tract. In an effort to reconcile such data scarcity, we deliver experimental-numerical correlations of 3D respiratory airflows in an idealized 3D printed mouth-throat model against two widely-established numerical schemes with varying computational costs, namely coarse RANS and finer LES technique. Our time-resolved 3D flow data underline the complexity of these physiological inhalation flows, and discuss advantages and drawbacks of the different numerical techniques. With an outlook on future respiratory applications geared towards broad preclinical inhaled aerosol deposition studies, our open source data are made available for future benchmark comparisons for a broad range of end users in the respiratory research community.

bioengineering↗

Ventilation-induced epithelial injury drives biological onset of lung trauma in vitro and is mitigated with anti-inflammatory therapeutics

Mortality rates among patients suffering from acute respiratory failure remain perplexingly high despite maintenance of blood homeostasis. The biotrauma hypothesis advances that mechanical forces from invasive ventilation trigger immunological factors that spread systemically. Yet, how these forces elicit an immune response remains unclear. Here we show that flow-induced stresses under mechanical ventilation can injure the bronchial epithelium of ventilated in vitro upper airway models and directly modulate inflammatory cytokine secretion associated with pulmonary injury. We identify site-specific susceptibility to epithelial erosion in airways from jet-flow impaction and measure an increase in cell apoptosis and modulated secretions of cytokines IL-6, 8 and 10. We find that prophylactic pharmacological treatment with anti-inflammatory therapeutics reduces apoptosis and pro-inflammatory signaling during ventilation. Our 3D in vitro airway platform points to a previously overlooked origin of lung injury and showcases translational opportunities in preclinical pulmonary research towards protective therapies and improved protocols for patient care.

bioengineering↗

Liquid foam therapy (LiFT) for homogenous distribution of exogenous pulmonary surfactant in ARDS

Lung surfactant dysfunction has a critical role in the pathophysiology of acute respiratory distress syndrome (ARDS). Yet, efforts to treat ARDS patients with liquid instillations of exogenous surfactant have so far failed. One of the ongoing challenges in surfactant therapy is obtaining a homogeneous distribution of surfactant within the lungs despite an inherent tendency to non-uniform spreading, owing amongst others to the influence of gravity. Here, we show that liquid foam therapy (LiFT), where surfactant is foamed prior to intratracheal administration, may improve notably surfactant distribution while maintaining safety and efficacy. We first show quantitatively that a foamed surrogate surfactant solution distributes more uniformly in ex vivo pig lungs compared to endotracheal instillations of the liquid solution, while maintaining pulmonary airway pressures within a safe range. Next, we demonstrate that a foamed commercial surfactant preparation (Infasurf) is effective in an established in vivo rat lung lavage model of ARDS. Our results suggest that LiFT may be more effective than liquid instillations for treating ARDS and serve as a proof-of-principle towards large animal and clinical trials.

pharmacology and toxicology↗