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Schmitz C, Welck J, Tavernaro I, Grinberg M, Rahnenführer J, Kiemer AK, van Thriel C, Hengstler JG, Kraegeloh A. Mechanical strain mimicking breathing amplifies alterations in gene expression induced by SiO 2 NPs in lung epithelial cells. Nanotoxicology 2019; 13:1227-1243. [PMID: 31418614 DOI: 10.1080/17435390.2019.1650971] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The effects of engineered nanomaterials on human health are still intensively studied in order to facilitate their safe application. However, relatively little is known how mechanical strain as induced in alveolar epithelial cells by breathing movements modifies biological responses to nanoparticles (NPs). In this study, A549 cells as a model for alveolar epithelial cells were exposed to 25 nm amorphous colloidal silica NPs under dynamic and static culture conditions. Gene array data, qPCR, and ELISA revealed an amplified effect of NPs when cells were mechanically stretched in order to model the physiological mechanical deformation during breathing. In contrast, treatment of cells with either strain or NPs alone only led to minor changes in gene expression or interleukin-8 (IL-8) secretion. Confocal microscopy revealed that stretching does not lead to an increased internalization of NPs, indicating that elevated intracellular NP accumulation is not responsible for the observed effect. Gene expression alterations induced by combined exposure to NPs and mechanical strain showed a high similarity to those known to be induced by TNF-α. This study suggests that the inclusion of mechanical strain into in vitro models of the human lung may have a strong influence on the test results.
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Affiliation(s)
- Carmen Schmitz
- INM-Leibniz Institute for New Materials , Saarbrücken , Germany.,Department of Pharmacy, Pharmaceutical Biology, Saarland University , Saarbrücken , Germany
| | - Jennifer Welck
- INM-Leibniz Institute for New Materials , Saarbrücken , Germany
| | | | - Marianna Grinberg
- Department of Statistics, TU Dortmund University , Dortmund , Germany
| | - Jörg Rahnenführer
- Department of Statistics, TU Dortmund University , Dortmund , Germany
| | - Alexandra K Kiemer
- Department of Pharmacy, Pharmaceutical Biology, Saarland University , Saarbrücken , Germany
| | - Christoph van Thriel
- IfADo-Leibniz Research Centre for Working Environment and Human Factors , Dortmund , Germany
| | - Jan G Hengstler
- IfADo-Leibniz Research Centre for Working Environment and Human Factors , Dortmund , Germany
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Khalilgharibi N, Fouchard J, Asadipour N, Barrientos R, Duda M, Bonfanti A, Yonis A, Harris A, Mosaffa P, Fujita Y, Kabla A, Mao Y, Baum B, Muñoz JJ, Miodownik M, Charras G. Stress relaxation in epithelial monolayers is controlled by the actomyosin cortex. NATURE PHYSICS 2019; 15:839-847. [PMID: 33569083 PMCID: PMC7116713 DOI: 10.1038/s41567-019-0516-6] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 04/01/2019] [Indexed: 05/19/2023]
Abstract
Epithelial monolayers are one-cell thick tissue sheets that line most of the body surfaces, separating internal and external environments. As part of their function, they must withstand extrinsic mechanical stresses applied at high strain rates. However, little is known about how monolayers respond to mechanical deformations. Here, by subjecting suspended epithelial monolayers to stretch, we find that they dissipate stresses on a minute timescale and that relaxation can be described by a power law with an exponential cut-off at timescales larger than ~10 s. This process involves an increase in monolayer length, pointing to active remodelling of cellular biopolymers at the molecular scale during relaxation. Strikingly, monolayers consisting of tens of thousands of cells relax stress with similar dynamics to single rounded cells and both respond similarly to perturbations of the actomyosin cytoskeleton. By contrast, cell-cell junctional complexes and intermediate filaments do not relax tissue stress, but form stable connections between cells, allowing monolayers to behave rheologically as single cells. Taken together our data show that actomyosin dynamics governs the rheological properties of epithelial monolayers, dissipating applied stresses, and enabling changes in monolayer length.
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Affiliation(s)
- Nargess Khalilgharibi
- London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, UK
- Centre for Computation, Mathematics and Physics in the Life Sciences and Experimental Biology (CoMPLEX), University College London, Gower Street, London WC1E 6BT, UK
| | - Jonathan Fouchard
- London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, UK
| | - Nina Asadipour
- Laboratori de Càlcul Numèric (LaCàN), Dept. Mathematics, Esc. d'Enginyeria Barcelona Est (EEBE), Universitat Politècnica de Catalunya - Barcelona Tech (UPC), 08036, Barcelona, Spain
| | - Ricardo Barrientos
- Centre for Computation, Mathematics and Physics in the Life Sciences and Experimental Biology (CoMPLEX), University College London, Gower Street, London WC1E 6BT, UK
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Maria Duda
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | | | - Amina Yonis
- London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, UK
- Department of Cell and Developmental Biology, University College London, UK
| | - Andrew Harris
- London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, UK
- Department of Physics, University College London, London WC1E 6BT, UK
- Engineering Doctorate Program, Department of Chemistry, University College London, London WC1H 0AJ, UK
- Department of Bioengineering and Biophysics Program, University of California, Berkeley, 648 Stanley Hall MC 1762, Berkeley, CA 94720, USA
| | - Payman Mosaffa
- Laboratori de Càlcul Numèric (LaCàN), Dept. Mathematics, Esc. d'Enginyeria Barcelona Est (EEBE), Universitat Politècnica de Catalunya - Barcelona Tech (UPC), 08036, Barcelona, Spain
| | | | - Alexandre Kabla
- Department of Mechanical Engineering, Cambridge University, UK
| | - Yanlan Mao
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Buzz Baum
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom
- Institute for the Physics of Living Systems, University College London, UK
| | - José J Muñoz
- Laboratori de Càlcul Numèric (LaCàN), Dept. Mathematics, Esc. d'Enginyeria Barcelona Est (EEBE), Universitat Politècnica de Catalunya - Barcelona Tech (UPC), 08036, Barcelona, Spain
- Barcelona Graduate School of Mathematics (BGSMath), Spain
| | - Mark Miodownik
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK
| | - Guillaume Charras
- London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, UK
- Department of Cell and Developmental Biology, University College London, UK
- Institute for the Physics of Living Systems, University College London, UK
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Scaramuzzo G, Broche L, Pellegrini M, Porra L, Derosa S, Tannoia AP, Marzullo A, Borges JB, Bayat S, Bravin A, Larsson A, Perchiazzi G. The Effect of Positive End-Expiratory Pressure on Lung Micromechanics Assessed by Synchrotron Radiation Computed Tomography in an Animal Model of ARDS. J Clin Med 2019; 8:E1117. [PMID: 31357677 PMCID: PMC6723999 DOI: 10.3390/jcm8081117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/17/2019] [Accepted: 07/25/2019] [Indexed: 02/06/2023] Open
Abstract
Modern ventilatory strategies are based on the assumption that lung terminal airspaces act as isotropic balloons that progressively accommodate gas. Phase contrast synchrotron radiation computed tomography (PCSRCT) has recently challenged this concept, showing that in healthy lungs, deflation mechanisms are based on the sequential de-recruitment of airspaces. Using PCSRCT scans in an animal model of acute respiratory distress syndrome (ARDS), this study examined whether the numerosity (ASnum) and dimension (ASdim) of lung airspaces change during a deflation maneuver at decreasing levels of positive end-expiratory pressure (PEEP) at 12, 9, 6, 3, and 0 cmH2O. Deflation was associated with significant reduction of ASdim both in the whole lung section (passing from from 13.1 ± 2.0 at PEEP 12 to 7.6 ± 4.2 voxels at PEEP 0) and in single concentric regions of interest (ROIs). However, the regression between applied PEEP and ASnum was significant in the whole slice (ranging from 188 ± 52 at PEEP 12 to 146.4 ± 96.7 at PEEP 0) but not in the single ROIs. This mechanism of deflation in which reduction of ASdim is predominant, differs from the one observed in healthy conditions, suggesting that the peculiar alveolar micromechanics of ARDS might play a role in the deflation process.
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Affiliation(s)
- Gaetano Scaramuzzo
- Department of Morphology, Surgery and Experimental Medicine, Ferrara University, 44121 Ferrara, Italy
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden
| | - Ludovic Broche
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden
| | - Mariangela Pellegrini
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden
- Department of Anesthesia and Intensive Care, Uppsala University Hospital, 75185 Uppsala, Sweden
| | - Liisa Porra
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
- Helsinki University Hospital, FI-00029 Helsinki, Finland
| | - Savino Derosa
- Department of Emergency and Organ Transplant, Bari University, 70124 Bari, Italy
| | | | - Andrea Marzullo
- Department of Emergency and Organ Transplant, Bari University, 70124 Bari, Italy
| | - João Batista Borges
- Centre for Human and Applied Physiological Sciences, Faculty of Sciences and Medicine, King's College, London WC2R 2LS, UK
| | - Sam Bayat
- The European Synchrotron Radiation Facility, 38043 Grenoble, France
- INSERM UA7, Synchrotron Radiation for Biomedicine (STROBE) Laboratory, University of Grenoble Alpes, 38043 Grenoble, France
| | - Alberto Bravin
- The European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - Anders Larsson
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden
| | - Gaetano Perchiazzi
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden.
- Department of Anesthesia and Intensive Care, Uppsala University Hospital, 75185 Uppsala, Sweden.
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Jorba I, Beltrán G, Falcones B, Suki B, Farré R, García-Aznar JM, Navajas D. Nonlinear elasticity of the lung extracellular microenvironment is regulated by macroscale tissue strain. Acta Biomater 2019; 92:265-276. [PMID: 31085362 DOI: 10.1016/j.actbio.2019.05.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 05/07/2019] [Accepted: 05/09/2019] [Indexed: 01/02/2023]
Abstract
The extracellular matrix (ECM) of the lung provides physical support and key mechanical signals to pulmonary cells. Although lung ECM is continuously subjected to different stretch levels, detailed mechanics of the ECM at the scale of the cell is poorly understood. Here, we developed a new polydimethylsiloxane (PDMS) chip to probe nonlinear mechanics of tissue samples with atomic force microscopy (AFM). Using this chip, we performed AFM measurements in decellularized rat lung slices at controlled stretch levels. The AFM revealed highly nonlinear ECM elasticity with the microscale stiffness increasing with tissue strain. To correlate micro- and macroscale ECM mechanics, we also assessed macromechanics of decellularized rat lung strips under uniaxial tensile testing. The lung strips exhibited exponential macromechanical behavior but with stiffness values one order of magnitude lower than at the microscale. To interpret the relationship between micro- and macromechanical properties, we carried out a finite element (FE) analysis which revealed that the stiffness of the alveolar cell microenvironment is regulated by the global strain of the lung scaffold. The FE modeling also indicates that the scale dependence of stiffness is mainly due to the porous architecture of the lung parenchyma. We conclude that changes in tissue strain during breathing result in marked changes in the ECM stiffness sensed by alveolar cells providing tissue-specific mechanical signals to the cells. STATEMENT OF SIGNIFICANCE: The micromechanical properties of the extracellular matrix (ECM) are a major determinant of cell behavior. The ECM is exposed to mechanical stretching in the lung and other organs during physiological function. Therefore, a thorough knowledge of the nonlinear micromechanical properties of the ECM at the length scale that cells probe is required to advance our understanding of cell-matrix interplay. We designed a novel PDMS chip to perform atomic force microscopy measurements of ECM micromechanics on decellularized rat lung slices at different macroscopic strain levels. For the first time, our results reveal that the microscale stiffness of lung ECM markedly increases with macroscopic tissue strain. Therefore, changes in tissue strain during breathing result in variations in ECM stiffness providing tissue-specific mechanical signals to lung cells.
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De Marco F, Willer K, Gromann LB, Andrejewski J, Hellbach K, Bähr A, Dmochewitz M, Koehler T, Maack HI, Pfeiffer F, Herzen J. Contrast-to-noise ratios and thickness-normalized, ventilation-dependent signal levels in dark-field and conventional in vivo thorax radiographs of two pigs. PLoS One 2019; 14:e0217858. [PMID: 31158251 PMCID: PMC6546243 DOI: 10.1371/journal.pone.0217858] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 05/20/2019] [Indexed: 12/20/2022] Open
Abstract
Lung tissue causes significant small-angle X-ray scattering, which can be visualized with grating-based X-ray dark-field imaging. Structural lung diseases alter alveolar microstructure, which often causes a dark-field signal decrease. The imaging method provides benefits for diagnosis of such diseases in small-animal models, and was successfully used on porcine and human lungs in a fringe-scanning setup. Micro- and macroscopic changes occur in the lung during breathing, but their individual effects on the dark-field signal are unknown. However, this information is important for quantitative medical evaluation of dark-field thorax radiographs. To estimate the effect of these changes on the dark-field signal during a clinical examination, we acquired in vivo dark-field chest radiographs of two pigs at three ventilation pressures. Pigs were used due to the high degree of similarity between porcine and human lungs. To analyze lung expansion separately, we acquired CT scans of both pigs at comparable posture and ventilation pressures. Segmentation, masking, and forward-projection of the CT datasets yielded maps of lung thickness and logarithmic lung attenuation signal in registration with the dark-field radiographs. Upon correlating this data, we discovered approximately linear relationships between the logarithmic dark-field signal and both projected quantities for all scans. Increasing ventilation pressure strongly decreased dark-field extinction coefficients, whereas the ratio of lung dark-field and attenuation signal changed only slightly. Furthermore, we investigated ratios of dark-field and attenuation noise levels at realistic signal levels via calculations and phantom measurements. Dark-field contrast-to-noise ratio (CNR) per lung height was 5 to 10% of the same quantity in attenuation. We conclude that better CNR performance in the dark-field modality is typically due to greater anatomical noise in the conventional radiograph. Given the high physiological similarity of human and porcine lungs, the presented thickness-normalized, ventilation-dependent values allow estimation of dark-field activity of human lungs of variable size and inspiration, which facilitates the design of suitable clinical imaging setups.
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Affiliation(s)
- Fabio De Marco
- Chair of Biomedical Physics & School of BioMedical Engineering, Technical University of Munich, Garching, Germany
| | - Konstantin Willer
- Chair of Biomedical Physics & School of BioMedical Engineering, Technical University of Munich, Garching, Germany
| | - Lukas B Gromann
- Chair of Biomedical Physics & School of BioMedical Engineering, Technical University of Munich, Garching, Germany
| | - Jana Andrejewski
- Chair of Biomedical Physics & School of BioMedical Engineering, Technical University of Munich, Garching, Germany
| | - Katharina Hellbach
- Department of Radiology, University Hospital, LMU Munich, Munich, Germany
| | - Andrea Bähr
- Institute of Molecular Animal Breeding and Biotechnology, LMU Munich, Oberschleissheim, Germany
| | - Michaela Dmochewitz
- Institute of Molecular Animal Breeding and Biotechnology, LMU Munich, Oberschleissheim, Germany
| | - Thomas Koehler
- Philips GmbH Innovative Technologies, Research Laboratories, Hamburg, Germany
- Institute for Advanced Study, Technical University of Munich, Garching, Germany
| | | | - Franz Pfeiffer
- Chair of Biomedical Physics & School of BioMedical Engineering, Technical University of Munich, Garching, Germany
- Institute for Advanced Study, Technical University of Munich, Garching, Germany
- Department of Diagnostic and Interventional Radiology, School of Medicine & Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Julia Herzen
- Chair of Biomedical Physics & School of BioMedical Engineering, Technical University of Munich, Garching, Germany
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Surfactant dysfunction and alveolar collapse are linked with fibrotic septal wall remodeling in the TGF-β1-induced mouse model of pulmonary fibrosis. J Transl Med 2019; 99:830-852. [PMID: 30700849 DOI: 10.1038/s41374-019-0189-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 11/20/2018] [Accepted: 12/17/2018] [Indexed: 11/08/2022] Open
Abstract
In human idiopathic pulmonary fibrosis (IPF), collapse of distal airspaces occurs in areas of the lung not (yet) remodeled. Mice lungs overexpressing transforming growth factor-β1 (TGF-β1) recapitulate this abnormality: surfactant dysfunction results in alveolar collapse preceding fibrosis and loss of alveolar epithelial type II (AE2) cells' apical membrane surface area. Here we examined whether surfactant dysfunction-related alveolar collapse due to TGF-β1 overexpression is linked to septal wall remodeling and AE2 cell abnormalities. Three and 6 days after gene transfer of TGF-β1, mice received either intratracheal surfactant (Surf-groups: Curosurf®, 100 mg/kg bodyweight) or 0.9% NaCl (Saline-groups). On days 7 (D7) and 14 (D14), lung mechanics were assessed followed by design-based stereology at light and electron microscopic level to quantify structures. Compared with Saline, Surf showed significantly improved tissue elastance, increased numbers of open alveoli, as well as reduced alveolar size heterogeneity on D7. Deterioration in lung mechanics was highly correlated to the loss of open alveoli. On D14, lung mechanics, number of open alveoli, and alveolar size heterogeneity remained significantly improved in the Surf-group. Volumes of extracellular matrix and collagen fibrils in septal walls were significantly reduced, whereas the apical membrane surface area of AE2 cells was increased in Surf compared with Saline. In remodeled tissue with collapsed alveoli, three-dimensional reconstruction of AE2 cells based on scanning electron microscopy array tomography revealed that AE2 cells were trapped without contact to airspaces in the TGF-β1 mouse model. Similar observations were made in human IPF. Based on correlation analyses, the number of open alveoli and of alveolar size heterogeneity were highly linked with the loss of apical membrane surface area of AE2 cells and deposition of collagen fibrils in septal walls on D14. In conclusion, surfactant replacement therapy stabilizes alveoli and prevents extracellular matrix deposition in septal walls in the TGF-β1 model.
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Koshiyama K, Nishimoto K, Ii S, Sera T, Wada S. Heterogeneous structure and surface tension effects on mechanical response in pulmonary acinus: A finite element analysis. Clin Biomech (Bristol, Avon) 2019; 66:32-39. [PMID: 29370949 DOI: 10.1016/j.clinbiomech.2018.01.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 12/07/2017] [Accepted: 01/08/2018] [Indexed: 02/07/2023]
Abstract
BACKGROUND The pulmonary acinus is a dead-end microstructure that consists of ducts and alveoli. High-resolution micro-CT imaging has recently provided detailed anatomical information of a complete in vivo acinus, but relating its mechanical response with its detailed acinar structure remains challenging. This study aimed to investigate the mechanical response of acinar tissue in a whole acinus for static inflation using computational approaches. METHODS We performed finite element analysis of a whole acinus for static inflation. The acinar structure model was generated based on micro-CT images of an intact acinus. A continuum mechanics model of the lung parenchyma was used for acinar tissue material model, and surface tension effects were explicitly included. An anisotropic mechanical field analysis based on a stretch tensor was combined with a curvature-based local structure analysis. FINDINGS The airspace of the acinus exhibited nonspherical deformation as a result of the anisotropic deformation of acinar tissue. A strain hotspot occurred at the ridge-shaped region caused by a rod-like deformation of acinar tissue on the ridge. The local structure becomes bowl-shaped for inflation and, without surface tension effects, the surface of the bowl-shaped region primarily experiences isotropic deformation. Surface tension effects suppressed the increase in airspace volume and inner surface area, while facilitating anisotropic deformation on the alveolar surface. INTERPRETATION In the lungs, the heterogeneous acinar structure and surface tension induce anisotropic deformation at the acinar and alveolar scales. Further research is needed on structural variation of acini, inter-acini connectivity, or dynamic behavior to understand multiscale lung mechanics.
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Affiliation(s)
| | | | - Satoshi Ii
- Graduate School of Engineering Science, Osaka University, Japan
| | - Toshihiro Sera
- Graduate School of Engineering Science, Osaka University, Japan
| | - Shigeo Wada
- Graduate School of Engineering Science, Osaka University, Japan
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LIU TIANYA, WANG YUXING, LIU XIAOYU, YUAN LAN, LI DEYU, QIAO HUITING, FAN YUBO. EFFECTS OF ALVEOLAR MORPHOLOGY ON ALVEOLAR MECHANICS: AN EXPERIMENTAL STUDY OF MOUSE LUNG BASED ON TWO- AND THREE-DIMENSIONAL IMAGING METHODS. J MECH MED BIOL 2019. [DOI: 10.1142/s0219519419500271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Understanding alveolar mechanics is important for preventing the possible lung injuries during mechanical ventilation. Alveolar clusters with smaller size are found having lower compliance in two-dimensional studies. But the influence of alveolar shape on compliance is unclear. In order to investigate how alveolar morphology affects their behavior, we tracked subpleural alveoli of isolated mouse lungs during quasi-static ventilation using two- and three-dimensional imaging techniques. Results showed that alveolar clusters with smaller size and more spherical shape had lower compliance. There was a better correlation of sphericity rather than circularity with alveolar compliance. The compliance of clusters with great shape change was larger than that with relatively slight shape change. These findings suggest the contribution of lung heterogeneous expansion to lung injuries associated with mechanical ventilation.
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Affiliation(s)
- TIANYA LIU
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, P. R. China
| | - YUXING WANG
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, P. R. China
| | - XIAOYU LIU
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, P. R. China
| | - LAN YUAN
- Beijing Key Laboratory of Rehabilitation Engineering for Elderly, National Research Center for Rehabilitation Technical Aids, Beijing 100176, P. R. China
| | - DEYU LI
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, P. R. China
| | - HUITING QIAO
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, P. R. China
| | - YUBO FAN
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, P. R. China
- Medical and Health Analysis Center, Peking University, Beijing 100191, P. R. China
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Springer R, Zielinski A, Pleschka C, Hoffmann B, Merkel R. Unbiased pattern analysis reveals highly diverse responses of cytoskeletal systems to cyclic straining. PLoS One 2019; 14:e0210570. [PMID: 30865622 PMCID: PMC6415792 DOI: 10.1371/journal.pone.0210570] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 12/26/2018] [Indexed: 01/09/2023] Open
Abstract
In mammalian cells, actin, microtubules, and various types of cytoplasmic intermediate filaments respond to external stretching. Here, we investigated the underlying processes in endothelial cells plated on soft substrates from silicone elastomer. After cyclic stretch (0.13 Hz, 14% strain amplitude) for periods ranging from 5 min to 8 h, cells were fixed and double-stained for microtubules and either actin or vimentin. Cell images were analyzed by a two-step routine. In the first step, micrographs were segmented for potential fibrous structures. In the second step, the resulting binary masks were auto- or cross-correlated. Autocorrelation of segmented images provided a sensitive and objective measure of orientational and translational order of the different cytoskeletal systems. Aligning of correlograms from individual cells removed the influence of only partial alignment between cells and enabled determination of intrinsic cytoskeletal order. We found that cyclic stretching affected the actin cytoskeleton most, microtubules less, and vimentin mostly only via reorientation of the whole cell. Pharmacological disruption of microtubules had barely any influence on actin ordering. The similarity, i.e., cross-correlation, between vimentin and microtubules was much higher than the one between actin and microtubules. Moreover, prolonged cyclic stretching slightly decoupled the cytoskeletal systems as it reduced the cross-correlations in both cases. Finally, actin and microtubules were more correlated at peripheral regions of cells whereas vimentin and microtubules correlated more in central regions.
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Affiliation(s)
- Ronald Springer
- Institute of Complex Systems 7, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Alexander Zielinski
- Institute of Complex Systems 7, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Catharina Pleschka
- Institute of Complex Systems 7, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Bernd Hoffmann
- Institute of Complex Systems 7, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Rudolf Merkel
- Institute of Complex Systems 7, Forschungszentrum Jülich GmbH, Jülich, Germany
- * E-mail:
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Modeling Airflow and Particle Deposition in a Human Acinar Region. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2019; 2019:5952941. [PMID: 30755779 PMCID: PMC6348927 DOI: 10.1155/2019/5952941] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 11/08/2018] [Accepted: 12/26/2018] [Indexed: 11/25/2022]
Abstract
The alveolar region, encompassing millions of alveoli, is the most vital part of the lung. However, airflow behavior and particle deposition in that region are not fully understood because of the complex geometrical structure and intricate wall movement. Although recent investigations using 3D computer simulations have provided some valuable information, a realistic analysis of the air-particle dynamics in the acinar region is still lacking. So, to gain better physical insight, a physiologically inspired whole acinar model has been developed. Specifically, air sacs (i.e., alveoli) were attached as partial spheroids to the bifurcating airway ducts, while breathing-related wall deformation was included to simulate actual alveolar expansion and contraction. Current model predictions confirm previous notions that the location of the alveoli greatly influences the alveolar flow pattern, with recirculating flow dominant in the proximal lung region. In the midalveolar lung generations, the intensity of the recirculating flow inside alveoli decreases while radial flow increases. In the distal alveolar region, the flow pattern is completely radial. The micron/submicron particle simulation results, employing the Euler–Lagrange modeling approach, indicate that deposition depends on the inhalation conditions and particle size. Specifically, the particle deposition rate in the alveolar region increases with higher inhalation tidal volume and particle diameter. Compared to previous acinar models, the present system takes into account the entire acinar region, including both partially alveolated respiratory bronchioles as well the fully alveolated distal airways and alveolar sacs. In addition, the alveolar expansion and contraction have been calculated based on physiological breathing conditions which make it easy to compare and validate model results with in vivo lung deposition measurements. Thus, the current work can be readily incorporated into human whole-lung airway models to simulate/predict the flow dynamics of toxic or therapeutic aerosols.
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Bailey KE, Floren ML, D'Ovidio TJ, Lammers SR, Stenmark KR, Magin CM. Tissue-informed engineering strategies for modeling human pulmonary diseases. Am J Physiol Lung Cell Mol Physiol 2019; 316:L303-L320. [PMID: 30461289 PMCID: PMC6397349 DOI: 10.1152/ajplung.00353.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/13/2018] [Accepted: 11/14/2018] [Indexed: 12/14/2022] Open
Abstract
Chronic pulmonary diseases, including idiopathic pulmonary fibrosis (IPF), pulmonary hypertension (PH), and chronic obstructive pulmonary disease (COPD), account for staggering morbidity and mortality worldwide but have limited clinical management options available. Although great progress has been made to elucidate the cellular and molecular pathways underlying these diseases, there remains a significant disparity between basic research endeavors and clinical outcomes. This discrepancy is due in part to the failure of many current disease models to recapitulate the dynamic changes that occur during pathogenesis in vivo. As a result, pulmonary medicine has recently experienced a rapid expansion in the application of engineering principles to characterize changes in human tissues in vivo and model the resulting pathogenic alterations in vitro. We envision that engineering strategies using precision biomaterials and advanced biomanufacturing will revolutionize current approaches to disease modeling and accelerate the development and validation of personalized therapies. This review highlights how advances in lung tissue characterization reveal dynamic changes in the structure, mechanics, and composition of the extracellular matrix in chronic pulmonary diseases and how this information paves the way for tissue-informed engineering of more organotypic models of human pathology. Current translational challenges are discussed as well as opportunities to overcome these barriers with precision biomaterial design and advanced biomanufacturing techniques that embody the principles of personalized medicine to facilitate the rapid development of novel therapeutics for this devastating group of chronic diseases.
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Affiliation(s)
- Kolene E Bailey
- Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Michael L Floren
- Cardiovascular Pulmonary Research Laboratories, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Tyler J D'Ovidio
- Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Steven R Lammers
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Kurt R Stenmark
- Cardiovascular Pulmonary Research Laboratories, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Chelsea M Magin
- Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
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62
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Kane AB, Hurt RH, Gao H. The asbestos-carbon nanotube analogy: An update. Toxicol Appl Pharmacol 2018; 361:68-80. [PMID: 29960000 PMCID: PMC6298811 DOI: 10.1016/j.taap.2018.06.027] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 06/11/2018] [Accepted: 06/26/2018] [Indexed: 01/16/2023]
Abstract
Nanotechnology is an emerging industry based on commercialization of materials with one or more dimensions of 100 nm or less. Engineered nanomaterials are currently incorporated into thin films, porous materials, liquid suspensions, or filler/matrix nanocomposites with future applications predicted in energy and catalysis, microelectronics, environmental sensing and remediation, and nanomedicine. Carbon nanotubes are one-dimensional fibrous nanomaterials that physically resemble asbestos fibers. Toxicologic studies in rodents demonstrated that some types of carbon nanotubes can induce mesothelioma, and the World Health Organization evaluated long, rigid multiwall carbon nanotubes as possibly carcinogenic for humans in 2014. This review summarizes key physicochemical similarities and differences between asbestos fibers and carbon nanotubes. The "fiber pathogenicity paradigm" has been extended to include carbon nanotubes as well as other high-aspect-ratio fibrous nanomaterials including metallic nanowires. This paradigm identifies width, length, and biopersistence of high-aspect-ratio fibrous nanomaterials as critical determinants of lung disease, including mesothelioma, following inhalation. Based on recent theoretical modeling studies, a fourth factor, mechanical bending stiffness, will be considered as predictive of potential carcinogenicity. Novel three-dimensional lung tissue platforms provide an opportunity for in vitro screening of a wide range of high aspect ratio fibrous nanomaterials for potential lung toxicity prior to commercialization.
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Affiliation(s)
- Agnes B Kane
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, United States; Institute for Molecular and Nanoscale Innovation, Providence, RI, United States.
| | - Robert H Hurt
- School of Engineering, Brown University, Providence, RI, United States; Institute for Molecular and Nanoscale Innovation, Providence, RI, United States
| | - Huajian Gao
- School of Engineering, Brown University, Providence, RI, United States; Institute for Molecular and Nanoscale Innovation, Providence, RI, United States
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63
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Scimone MT, Cramer III HC, Bar-Kochba E, Amezcua R, Estrada JB, Franck C. Modular approach for resolving and mapping complex neural and other cellular structures and their associated deformation fields in three dimensions. Nat Protoc 2018; 13:3042-3064. [DOI: 10.1038/s41596-018-0077-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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64
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Knudsen L, Ochs M. The micromechanics of lung alveoli: structure and function of surfactant and tissue components. Histochem Cell Biol 2018; 150:661-676. [PMID: 30390118 PMCID: PMC6267411 DOI: 10.1007/s00418-018-1747-9] [Citation(s) in RCA: 179] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2018] [Indexed: 12/14/2022]
Abstract
The mammalian lung´s structural design is optimized to serve its main function: gas exchange. It takes place in the alveolar region (parenchyma) where air and blood are brought in close proximity over a large surface. Air reaches the alveolar lumen via a conducting airway tree. Blood flows in a capillary network embedded in inter-alveolar septa. The barrier between air and blood consists of a continuous alveolar epithelium (a mosaic of type I and type II alveolar epithelial cells), a continuous capillary endothelium and the connective tissue layer in-between. By virtue of its respiratory movements, the lung has to withstand mechanical challenges throughout life. Alveoli must be protected from over-distension as well as from collapse by inherent stabilizing factors. The mechanical stability of the parenchyma is ensured by two components: a connective tissue fiber network and the surfactant system. The connective tissue fibers form a continuous tensegrity (tension + integrity) backbone consisting of axial, peripheral and septal fibers. Surfactant (surface active agent) is the secretory product of type II alveolar epithelial cells and covers the alveolar epithelium as a biophysically active thin and continuous film. Here, we briefly review the structural components relevant for gas exchange. Then we describe our current understanding of how these components function under normal conditions and how lung injury results in dysfunction of alveolar micromechanics finally leading to lung fibrosis.
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Affiliation(s)
- Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany.,REBIRTH Cluster of Excellence, Hannover, Germany
| | - Matthias Ochs
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. .,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany. .,REBIRTH Cluster of Excellence, Hannover, Germany.
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65
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Physiological and structural changes of the lung tissue in male albino rat exposed to immobilization stress. J Cell Physiol 2018; 234:9168-9183. [DOI: 10.1002/jcp.27594] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 09/19/2018] [Indexed: 12/31/2022]
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66
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Silva PL, Gama de Abreu M. Regional distribution of transpulmonary pressure. ANNALS OF TRANSLATIONAL MEDICINE 2018; 6:385. [PMID: 30460259 DOI: 10.21037/atm.2018.10.03] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The pressure across the lung, so-called transpulmonary pressure (PL), represents the main force acting toward to provide lung movement. During mechanical ventilation, PL is provided by respiratory system pressurization, using specific ventilator setting settled by the operator, such as: tidal volume (VT), positive end-expiratory pressure (PEEP), respiratory rate (RR), and inspiratory airway flow. Once PL is developed throughout the lungs, its distribution is heterogeneous, being explained by the elastic properties of the lungs and pleural pressure gradient. There are different methods of PL calculation, each one with importance and some limitations. Among the most known, it can be quoted: (I) direct measurement of PL; (II) elastance derived method at end-inspiration of PL; (III) transpulmonary driving pressure. Recent studies using pleural sensors in large animal models as also in human cadaver have added new and important information about PL heterogeneous distribution across the lungs. Due to this heterogeneous distribution, lung damage could happen in specific areas of the lung. In addition, it is widely accepted that high PL can cause lung damage, however the way it is delivered, whether it's compressible or tensile, may also further damage despite the values of PL achieved. According to heterogeneous distribution of PL across the lungs, the interstitium and lymphatic vessels may also interplay to disseminate lung inflammation toward peripheral organs through thoracic lymph tracts. Thus, it is conceivable that juxta-diaphragmatic area associated strong efforts leading to high values of PL may be a source of dissemination of inflammatory cells, large molecules, and plasma contents able to perpetuate inflammation in distal organs.
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Affiliation(s)
- Pedro Leme Silva
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marcelo Gama de Abreu
- Pulmonary Engineering Group, Department of Anesthesiology and Intensive Care, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
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67
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Medium throughput breathing human primary cell alveolus-on-chip model. Sci Rep 2018; 8:14359. [PMID: 30254327 PMCID: PMC6156575 DOI: 10.1038/s41598-018-32523-x] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 09/10/2018] [Indexed: 12/12/2022] Open
Abstract
Organs-on-chips have the potential to improve drug development efficiency and decrease the need for animal testing. For the successful integration of these devices in research and industry, they must reproduce in vivo contexts as closely as possible and be easy to use. Here, we describe a ‘breathing’ lung-on-chip array equipped with a passive medium exchange mechanism that provide an in vivo-like environment to primary human lung alveolar cells (hAEpCs) and primary lung endothelial cells. This configuration allows the preservation of the phenotype and the function of hAEpCs for several days, the conservation of the epithelial barrier functionality, while enabling simple sampling of the supernatant from the basal chamber. In addition, the chip design increases experimental throughput and enables trans-epithelial electrical resistance measurements using standard equipment. Biological validation revealed that human primary alveolar type I (ATI) and type II-like (ATII) epithelial cells could be successfully cultured on the chip over multiple days. Moreover, the effect of the physiological cyclic strain showed that the epithelial barrier permeability was significantly affected. Long-term co-culture of primary human lung epithelial and endothelial cells demonstrated the potential of the lung-on-chip array for reproducible cell culture under physiological conditions. Thus, this breathing lung-on-chip array, in combination with patients’ primary ATI, ATII, and lung endothelial cells, has the potential to become a valuable tool for lung research, drug discovery and precision medicine.
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68
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Arefin A, Mcculloch Q, Martinez R, Martin SA, Singh R, Ishak OM, Higgins EM, Haffey KE, Huang JH, Iyer S, Nath P, Iyer R, Harris JF. Micromachining of Polyurethane Membranes for Tissue Engineering Applications. ACS Biomater Sci Eng 2018; 4:3522-3533. [DOI: 10.1021/acsbiomaterials.8b00578] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Ayesha Arefin
- Nanoscience and Microsystems Department, University of New Mexico, MSC01 1120, 1 University of New Mexico, Albuquerque, New Mexico 87131, United States
- Bioscience Division, Los Alamos National Laboratory, P.O. Box 1663 MS M888, Los Alamos, New Mexico 87545, United States
| | - Quinn Mcculloch
- Nanoscience and Microsystems Department, University of New Mexico, MSC01 1120, 1 University of New Mexico, Albuquerque, New Mexico 87131, United States
- MPA-CINT: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, P.O.
Box 1663 MS K771, Los Alamos, New Mexico 87545, United States
| | - Ricardo Martinez
- MPA-CINT: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, P.O.
Box 1663 MS K771, Los Alamos, New Mexico 87545, United States
| | - Simona A. Martin
- Bioscience Division, Los Alamos National Laboratory, P.O. Box 1663 MS M888, Los Alamos, New Mexico 87545, United States
| | - Rohan Singh
- C-PCS: Physical Chemistry & Applied Spectroscopy, Los Alamos National Laboratory, P.O. Box 1663 MS J567, Los Alamos, New Mexico 87545, United States
| | - Omar M. Ishak
- Bioscience Division, Los Alamos National Laboratory, P.O. Box 1663 MS M888, Los Alamos, New Mexico 87545, United States
| | - Erin M. Higgins
- Applied Modern Physics Division, Los Alamos National Laboratory, P.O. Box 1663 MS D454, Los Alamos, New Mexico 87545, United States
| | - Kiersten E. Haffey
- Applied Modern Physics Division, Los Alamos National Laboratory, P.O. Box 1663 MS D454, Los Alamos, New Mexico 87545, United States
| | - Jen-Huang Huang
- Bioscience Division, Los Alamos National Laboratory, P.O. Box 1663 MS M888, Los Alamos, New Mexico 87545, United States
| | - Srinivas Iyer
- Bioscience Division, Los Alamos National Laboratory, P.O. Box 1663 MS M888, Los Alamos, New Mexico 87545, United States
| | - Pulak Nath
- Applied Modern Physics Division, Los Alamos National Laboratory, P.O. Box 1663 MS D454, Los Alamos, New Mexico 87545, United States
| | - Rashi Iyer
- Systems Analysis and Surveillance Division, Los Alamos National Laboratory, P.O. Box
1663 MS C921, Los Alamos, New Mexico 87545, United States
| | - Jennifer F. Harris
- Bioscience Division, Los Alamos National Laboratory, P.O. Box 1663 MS M888, Los Alamos, New Mexico 87545, United States
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69
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Guenat OT, Berthiaume F. Incorporating mechanical strain in organs-on-a-chip: Lung and skin. BIOMICROFLUIDICS 2018; 12:042207. [PMID: 29861818 PMCID: PMC5962443 DOI: 10.1063/1.5024895] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 04/17/2018] [Indexed: 05/08/2023]
Abstract
In the last decade, the advent of microfabrication and microfluidics and an increased interest in cellular mechanobiology have triggered the development of novel microfluidic-based platforms. They aim to incorporate the mechanical strain environment that acts upon tissues and in-vivo barriers of the human body. This article reviews those platforms, highlighting the different strains applied, and the actuation mechanisms and provides representative applications. A focus is placed on the skin and the lung barriers as examples, with a section that discusses the signaling pathways involved in the epithelium and the connective tissues.
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Affiliation(s)
| | - François Berthiaume
- Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey, 08854, USA
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70
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Bellezzia MA, Cruz FF, Martins V, de Castro LL, Lopes-Pacheco M, Vilanova EP, Mourão PA, Rocco PRM, Silva PL. Impact of different intratracheal flows during lung decellularization on extracellular matrix composition and mechanics. Regen Med 2018; 13:519-530. [DOI: 10.2217/rme-2018-0008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Aim: To evaluate different intratracheal flow rates on extracellular matrix content and lung mechanics in an established lung decellularization protocol. Materials & methods: Healthy mice were used: 15 for decellularization and five to serve as controls. Fluids were instilled at 5, 10 and 20 ml/min flow rates through tracheal cannula and right ventricular cavity (0.5 ml/min) in all groups. Results: The 20 ml/min rate better preserved collagen content in decellularized lungs. Elastic fiber content decreased at 5 and 10 ml/min, but not at 20 ml/min, compared with controls. Chondroitin, heparan and dermatan content was reduced after decellularization. Conclusion: An intratracheal flow rate of 20 ml/min was associated with lower resistance and greater preservation of collagen to that observed in ex vivo control lungs.
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Affiliation(s)
- Mariana Alves Bellezzia
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, RJ, Brazil
- National Institute of Science & Technology for Regenerative Medicine, Rio de Janeiro, RJ, Brazil
| | - Fernanda F Cruz
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, RJ, Brazil
- National Institute of Science & Technology for Regenerative Medicine, Rio de Janeiro, RJ, Brazil
| | - Vanessa Martins
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, RJ, Brazil
- Laboratory of Histomorphometry & Lung Genomics, University of São Paulo Faculty of Medicine, São Paulo, SP, Brazil
| | - Lígia Lins de Castro
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, RJ, Brazil
- National Institute of Science & Technology for Regenerative Medicine, Rio de Janeiro, RJ, Brazil
| | - Miquéias Lopes-Pacheco
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, RJ, Brazil
- National Institute of Science & Technology for Regenerative Medicine, Rio de Janeiro, RJ, Brazil
| | - Eduardo Prata Vilanova
- Glycobiology Program, Leopoldo de Meis Medical Biochemistry Institute, Connective Tissue Laboratory, Clementino Fraga Filho University Hospital, Federal University of Rio de Janeiro, RJ, Brazil
| | - Paulo A Mourão
- Glycobiology Program, Leopoldo de Meis Medical Biochemistry Institute, Connective Tissue Laboratory, Clementino Fraga Filho University Hospital, Federal University of Rio de Janeiro, RJ, Brazil
| | - Patricia RM Rocco
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, RJ, Brazil
- National Institute of Science & Technology for Regenerative Medicine, Rio de Janeiro, RJ, Brazil
| | - Pedro L Silva
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, RJ, Brazil
- National Institute of Science & Technology for Regenerative Medicine, Rio de Janeiro, RJ, Brazil
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71
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Chung HH, Mireles M, Kwarta BJ, Gaborski TR. Use of porous membranes in tissue barrier and co-culture models. LAB ON A CHIP 2018; 18:1671-1689. [PMID: 29845145 PMCID: PMC5997570 DOI: 10.1039/c7lc01248a] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Porous membranes enable the partitioning of cellular microenvironments in vitro, while still allowing physical and biochemical crosstalk between cells, a feature that is often necessary for recapitulating physiological functions. This article provides an overview of the different membranes used in tissue barrier and cellular co-culture models with a focus on experimental design and control of these systems. Specifically, we discuss how the structural, mechanical, chemical, and even the optical and transport properties of different membranes bestow specific advantages and disadvantages through the context of physiological relevance. This review also explores how membrane pore properties affect perfusion and solute permeability by developing an analytical framework to guide the design and use of tissue barrier or co-culture models. Ultimately, this review offers insight into the important aspects one must consider when using porous membranes in tissue barrier and lab-on-a-chip applications.
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Affiliation(s)
- Henry H Chung
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, NY, USA.
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72
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Asmani M, Velumani S, Li Y, Wawrzyniak N, Hsia I, Chen Z, Hinz B, Zhao R. Fibrotic microtissue array to predict anti-fibrosis drug efficacy. Nat Commun 2018; 9:2066. [PMID: 29802256 PMCID: PMC5970268 DOI: 10.1038/s41467-018-04336-z] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 04/23/2018] [Indexed: 02/07/2023] Open
Abstract
Fibrosis is a severe health problem characterized by progressive stiffening of tissues which causes organ malfunction and failure. A major bottleneck in developing new anti-fibrosis therapies is the lack of in vitro models that recapitulate dynamic changes in tissue mechanics during fibrogenesis. Here we create membranous human lung microtissues to model key biomechanical events occurred during lung fibrogenesis including progressive stiffening and contraction of alveolar tissue, decline in alveolar tissue compliance and traction force-induced bronchial dilation. With these capabilities, we provide proof of principle for using this fibrotic tissue array for multi-parameter, phenotypic analysis of the therapeutic efficacy of two anti-fibrosis drugs recently approved by the FDA. Preventative treatments with Pirfenidone and Nintedanib reduce tissue contractility and prevent tissue stiffening and decline in tissue compliance. In a therapeutic treatment regimen, both drugs restore tissue compliance. These results highlight the pathophysiologically relevant modeling capability of our novel fibrotic microtissue system.
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Affiliation(s)
- Mohammadnabi Asmani
- Department of Biomedical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
| | - Sanjana Velumani
- Department of Biomedical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
| | - Yan Li
- Department of Biomedical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
| | - Nicole Wawrzyniak
- Department of Biomedical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
| | - Isaac Hsia
- Department of Biomedical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
| | - Zhaowei Chen
- Department of Biomedical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
| | - Boris Hinz
- Laboratory of Tissue Repair and Regeneration, Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON, M5S 3E2, Canada.,Institute of Biomaterials & Biomedical Engineering, University of Toronto, Toronto, ON, M5S 3G9, Canada
| | - Ruogang Zhao
- Department of Biomedical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA.
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73
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De Monte V, Bufalari A, Grasso S, Ferrulli F, Crovace AM, Lacitignola L, Staffieri F. Respiratory effects of low versus high tidal volume with or without positive end-expiratory pressure in anesthetized dogs with healthy lungs. Am J Vet Res 2018; 79:496-504. [DOI: 10.2460/ajvr.79.5.496] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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74
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Gouveia L, Betsholtz C, Andrae J. PDGF-A signaling is required for secondary alveolar septation and controls epithelial proliferation in the developing lung. Development 2018; 145:145/7/dev161976. [DOI: 10.1242/dev.161976] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 03/13/2018] [Indexed: 01/25/2023]
Abstract
ABSTRACT
Platelet-derived growth factor A (PDGF-A) signaling through PDGF receptor α is essential for alveogenesis. Previous studies have shown that Pdgfa−/− mouse lungs have enlarged alveolar airspace with absence of secondary septation, both distinctive features of bronchopulmonary dysplasia. To study how PDGF-A signaling is involved in alveogenesis, we generated lung-specific Pdgfa knockout mice (Pdgfafl/−; Spc-cre) and characterized their phenotype postnatally. Histological differences between mutant mice and littermate controls were visible after the onset of alveogenesis and maintained until adulthood. Additionally, we generated Pdgfafl/−; Spc-cre; PdgfraGFP/+ mice in which Pdgfra+ cells exhibit nuclear GFP expression. In the absence of PDGF-A, the number of PdgfraGFP+ cells was significantly decreased. In addition, proliferation of PdgfraGFP+ cells was reduced. During alveogenesis, PdgfraGFP+ myofibroblasts failed to form the α-smooth muscle actin rings necessary for alveolar secondary septation. These results indicate that PDGF-A signaling is involved in myofibroblast proliferation and migration. In addition, we show an increase in both the number and proliferation of alveolar type II cells in Pdgfafl/−; Spc-cre lungs, suggesting that the increased alveolar airspace is not caused solely by deficient myofibroblast function.
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Affiliation(s)
- Leonor Gouveia
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala, Sweden
| | - Christer Betsholtz
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala, Sweden
- Integrated Cardio Metabolic Centre, Karolinska Institute, SE-141 57 Huddinge, Sweden
| | - Johanna Andrae
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala, Sweden
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75
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Zscheppang K, Berg J, Hedtrich S, Verheyen L, Wagner DE, Suttorp N, Hippenstiel S, Hocke AC. Human Pulmonary 3D Models For Translational Research. Biotechnol J 2018; 13:1700341. [PMID: 28865134 PMCID: PMC7161817 DOI: 10.1002/biot.201700341] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 08/23/2017] [Indexed: 12/13/2022]
Abstract
Lung diseases belong to the major causes of death worldwide. Recent innovative methodological developments now allow more and more for the use of primary human tissue and cells to model such diseases. In this regard, the review covers bronchial air-liquid interface cultures, precision cut lung slices as well as ex vivo cultures of explanted peripheral lung tissue and de-/re-cellularization models. Diseases such as asthma or infections are discussed and an outlook on further areas for development is given. Overall, the progress in ex vivo modeling by using primary human material could make translational research activities more efficient by simultaneously fostering the mechanistic understanding of human lung diseases while reducing animal usage in biomedical research.
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Affiliation(s)
- Katja Zscheppang
- Dept. of Internal Medicine/Infectious and Respiratory DiseasesCharité − Universitätsmedizin BerlinCharitèplatz 1Berlin 10117Germany
| | - Johanna Berg
- Department of BiotechnologyTechnical University of BerlinGustav‐Meyer‐Allee 25Berlin 13335Germany
| | - Sarah Hedtrich
- Institute for PharmacyPharmacology and ToxicologyFreie Universität BerlinBerlinGermany
| | - Leonie Verheyen
- Institute for PharmacyPharmacology and ToxicologyFreie Universität BerlinBerlinGermany
| | - Darcy E. Wagner
- Helmholtz Zentrum Munich, Lung Repair and Regeneration Unit, Comprehensive Pneumology CenterMember of the German Center for Lung ResearchMunichGermany
| | - Norbert Suttorp
- Dept. of Internal Medicine/Infectious and Respiratory DiseasesCharité − Universitätsmedizin BerlinCharitèplatz 1Berlin 10117Germany
| | - Stefan Hippenstiel
- Dept. of Internal Medicine/Infectious and Respiratory DiseasesCharité − Universitätsmedizin BerlinCharitèplatz 1Berlin 10117Germany
| | - Andreas C. Hocke
- Dept. of Internal Medicine/Infectious and Respiratory DiseasesCharité − Universitätsmedizin BerlinCharitèplatz 1Berlin 10117Germany
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Thomas AN, Borden MA. Hydrostatic Pressurization of Lung Surfactant Microbubbles: Observation of a Strain-Rate Dependent Elasticity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13699-13707. [PMID: 29064252 DOI: 10.1021/acs.langmuir.7b03307] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The microbubble offers a unique platform to study lung surfactant mechanics at physiologically relevant geometry and length scale. In this study, we compared the response of microbubbles (∼15 μm initial radius) coated with pure dipalmitoyl-phosphatidylcholine (DPPC) versus naturally derived lung surfactant (SURVANTA) when subjected to linearly increasing hydrostatic pressure at different rates (0.5-2.3 kPa/s) at room temperature. The microbubbles contained perfluorobutane gas and were submerged in buffered saline saturated with perfluorobutane at atmospheric pressure. Bright-field microscopy showed that DPPC microbubbles compressed spherically and smoothly, whereas SURVANTA microbubbles exhibited wrinkling and smoothing cycles associated with buckling and collapse. Seismograph analysis showed that the SURVANTA collapse amplitude was constant, but the collapse rate increased with the pressurization rate. An analysis of the pressure-volume curves indicated that the dilatational elasticity increased during compression for both shell types. The initial dilatational elasticity for SURVANTA was nearly twice that of DPPC at higher pressurization rates (>1.5 kPa/s), producing a pressure drop of up to 60 kPa across the film prior to condensation of the perfluorobutane core. The strain-rate dependent stiffening of SURVANTA shells likely arises from their composition and microstructure, which provide enhanced in-plane monolayer rigidity and lateral repulsion from surface-associated collapse structures. Overall, these results provide new insights into lung surfactant mechanics and collapse behavior during compression.
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Affiliation(s)
- Alec N Thomas
- Department of Mechanical Engineering and ‡Materials Science and Engineering Program, University of Colorado , Boulder, Colorado 80309, United States
| | - Mark A Borden
- Department of Mechanical Engineering and ‡Materials Science and Engineering Program, University of Colorado , Boulder, Colorado 80309, United States
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77
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Kollisch-Singule MC, Jain SV, Andrews PL, Satalin J, Gatto LA, Villar J, De Backer D, Gattinoni L, Nieman GF, Habashi NM. Looking beyond macroventilatory parameters and rethinking ventilator-induced lung injury. J Appl Physiol (1985) 2017; 124:1214-1218. [PMID: 29146685 DOI: 10.1152/japplphysiol.00412.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
| | - Sumeet V Jain
- Department of Surgery, SUNY Upstate Medical University , Syracuse, New York
| | - Penny L Andrews
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine , Baltimore, Maryland
| | - Joshua Satalin
- Department of Surgery, SUNY Upstate Medical University , Syracuse, New York
| | - Louis A Gatto
- Department of Surgery, SUNY Upstate Medical University , Syracuse, New York.,Department of Biological Sciences, SUNY Cortland, Cortland, New York
| | - Jesús Villar
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III , Madrid , Spain.,Research Unit, Hospital Universitario Dr. Negrin , Las Palmas de Gran Canaria , Spain
| | - Daniel De Backer
- Department of Intensive Care, CHIREC Hospitals, Université Libre de Bruxelles , Brussels , Belgium
| | - Luciano Gattinoni
- Department of Anesthesia and Intensive Care, Georg-August-Universität, Göttingen , Germany
| | - Gary F Nieman
- Department of Surgery, SUNY Upstate Medical University , Syracuse, New York
| | - Nader M Habashi
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine , Baltimore, Maryland
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78
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Langdon R, Docherty PD, Schranz C, Chase JG. Prediction of high airway pressure using a non-linear autoregressive model of pulmonary mechanics. Biomed Eng Online 2017; 16:126. [PMID: 29096634 PMCID: PMC5668972 DOI: 10.1186/s12938-017-0415-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 10/25/2017] [Indexed: 11/25/2022] Open
Abstract
Background For mechanically ventilated patients with acute respiratory distress syndrome (ARDS), suboptimal PEEP levels can cause ventilator induced lung injury (VILI). In particular, high PEEP and high peak inspiratory pressures (PIP) can cause over distension of alveoli that is associated with VILI. However, PEEP must also be sufficient to maintain recruitment in ARDS lungs. A lung model that accurately and precisely predicts the outcome of an increase in PEEP may allow dangerous high PIP to be avoided, and reduce the incidence of VILI. Methods and results Sixteen pressure-flow data sets were collected from nine mechanically ventilated ARDs patients that underwent one or more recruitment manoeuvres. A nonlinear autoregressive (NARX) model was identified on one or more adjacent PEEP steps, and extrapolated to predict PIP at 2, 4, and 6 cmH2O PEEP horizons. The analysis considered whether the predicted and measured PIP exceeded a threshold of 40 cmH2O. A direct comparison of the method was made using the first order model of pulmonary mechanics (FOM(I)). Additionally, a further, more clinically appropriate method for the FOM was tested, in which the FOM was trained on a single PEEP prior to prediction (FOM(II)). The NARX model exhibited very high sensitivity (> 0.96) in all cases, and a high specificity (> 0.88). While both FOM methods had a high specificity (> 0.96), the sensitivity was much lower, with a mean of 0.68 for FOM(I), and 0.82 for FOM(II). Conclusions Clinically, false negatives are more harmful than false positives, as a high PIP may result in distension and VILI. Thus, the NARX model may be more effective than the FOM in allowing clinicians to reduce the risk of applying a PEEP that results in dangerously high airway pressures.
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Affiliation(s)
- Ruby Langdon
- Department of Mechanical Engineering, University of Canterbury, Private bag 4800, Christchurch, 8140, New Zealand
| | - Paul D Docherty
- Department of Mechanical Engineering, University of Canterbury, Private bag 4800, Christchurch, 8140, New Zealand.
| | | | - J Geoffrey Chase
- Department of Mechanical Engineering, University of Canterbury, Private bag 4800, Christchurch, 8140, New Zealand
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79
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McGowan SE, McCoy DM. Platelet-derived growth factor receptor-α and Ras-related C3 botulinum toxin substrate-1 regulate mechano-responsiveness of lung fibroblasts. Am J Physiol Lung Cell Mol Physiol 2017; 313:L1174-L1187. [PMID: 28775097 DOI: 10.1152/ajplung.00185.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 07/27/2017] [Accepted: 07/27/2017] [Indexed: 12/23/2022] Open
Abstract
Platelet-derived growth factor (PDGF)-A, which only signals through PDGF-receptor-α (PDGFR-α), is required for secondary alveolar septal formation. Although PDGFR-α distinguishes mesenchymal progenitor cells during the saccular stage, PDGFR-α-expressing alveolar cells persist through adulthood. PDGF-A sustains proliferation, limits apoptosis, and maintains α-smooth muscle actin (α-SMA)-containing alveolar cells, which congregate at the alveolar entry ring at postnatal day (P)12. PDGFR-α-expressing, α-SMA-containing alveolar cells redistribute in the elongating septum, suggesting that they migrate to the alveolar entry rings, where mechanical tension is higher. We hypothesized that PDGFR-α and Ras-related C3 botulinum toxin substrate 1(Rac1) are required for mechanosensitive myofibroblast migration. Spreading of PDGFR-α-deficient lung fibroblasts was insensitive to increased rigidity, and their migration was not reduced by Rac1-guanine exchange factor (GEF)-inhibition. PDGFR-α-expressing fibroblasts migrated toward stiffer regions within two-dimensional substrates by increasing migrational persistence (durotaxis). Using a Förster resonance energy transfer (FRET) biosensor for Rac1-GTP, we observed that PDGFR-α was required for fibroblast Rac1 responsiveness to stiffness within a three-dimensional collagen substrate, which by itself increased Rac1-FRET. Rho-GTPase stabilized, whereas Rac1-GTPase increased the turnover of focal adhesions. Under conditions that increased Rac1-GTP, PDGFR-α signaled through both phosphoinositide-3-kinase (PIK) or Src to engage the Rac1 GEF dedicator of cytokinesis-1 (Dock180) and p21-activated-kinase interacting exchange factor-β (βPIX). In cooperation with collagen fibers, these signaling pathways may guide fibroblasts toward the more rigid alveolar entry ring during secondary septation. Because emphysema and interstitial fibrosis disrupt the parenchymal mechanical continuum, understanding how mechanical factors regulate fibroblast migration could elicit strategies for alveolar repair and regeneration.
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Affiliation(s)
- Stephen E McGowan
- Department of Veterans Affairs Research Service and Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Diann M McCoy
- Department of Veterans Affairs Research Service and Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
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80
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Nieman GF, Satalin J, Kollisch-Singule M, Andrews P, Aiash H, Habashi NM, Gatto LA. Physiology in Medicine: Understanding dynamic alveolar physiology to minimize ventilator-induced lung injury. J Appl Physiol (1985) 2017; 122:1516-1522. [PMID: 28385915 PMCID: PMC7203565 DOI: 10.1152/japplphysiol.00123.2017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 03/16/2017] [Accepted: 04/03/2017] [Indexed: 02/01/2023] Open
Abstract
Acute respiratory distress syndrome (ARDS) remains a serious clinical problem with the main treatment being supportive in the form of mechanical ventilation. However, mechanical ventilation can be a double-edged sword: if set improperly, it can exacerbate the tissue damage caused by ARDS; this is known as ventilator-induced lung injury (VILI). To minimize VILI, we must understand the pathophysiologic mechanisms of tissue damage at the alveolar level. In this Physiology in Medicine paper, the dynamic physiology of alveolar inflation and deflation during mechanical ventilation will be reviewed. In addition, the pathophysiologic mechanisms of VILI will be reviewed, and this knowledge will be used to suggest an optimal mechanical breath profile (MBP: all airway pressures, volumes, flows, rates, and the duration that they are applied at both inspiration and expiration) necessary to minimize VILI. Our review suggests that the current protective ventilation strategy, known as the "open lung strategy," would be the optimal lung-protective approach. However, the viscoelastic behavior of dynamic alveolar inflation and deflation has not yet been incorporated into protective mechanical ventilation strategies. Using our knowledge of dynamic alveolar mechanics (i.e., the dynamic change in alveolar and alveolar duct size and shape during tidal ventilation) to modify the MBP so as to minimize VILI will reduce the morbidity and mortality associated with ARDS.
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Affiliation(s)
- Gary F Nieman
- State University of New York Upstate Medical University, Syracuse, New York
| | - Josh Satalin
- State University of New York Upstate Medical University, Syracuse, New York;
| | | | - Penny Andrews
- R Adams Cowley Shock Trauma Center, Baltimore, Maryland
| | - Hani Aiash
- State University of New York Upstate Medical University, Syracuse, New York
- Suez Canal University, Ismailia, Egypt; and
| | | | - Louis A Gatto
- State University of New York Upstate Medical University, Syracuse, New York
- State University of New York Cortland, Cortland, New York
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81
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Takahashi K, Ito S, Furuya K, Asano S, Sokabe M, Hasegawa Y. Real-time imaging of mechanically and chemically induced ATP release in human lung fibroblasts. Respir Physiol Neurobiol 2017; 242:96-101. [PMID: 28442443 DOI: 10.1016/j.resp.2017.04.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 04/19/2017] [Accepted: 04/19/2017] [Indexed: 12/26/2022]
Abstract
Extracellular adenosine 5'-triphosphate (ATP) acts as an inflammatory mediator of pulmonary fibrosis. We investigated the effects of mechanical and chemical stimuli on ATP release from primary normal human lung fibroblasts. We visualized the ATP release from fibroblasts in real time using a luminescence imaging system while acquiring differential interference contrast cell images with infrared optics. Immediately following a single uniaxial stretch for 1s, ATP was released from a certain population of cells and spread to surrounding spaces. Hypotonic stress, which causes plasma membrane stretching, also induced the ATP release. Compared with the effects of mechanical stretch, ATP-induced release sites were homogeneously distributed. In contrast to the effects of mechanical stimuli, application of platelet-derived growth factor caused ATP release from small numbers of the cells. Our real-time ATP imaging demonstrates that there is a heterogeneous nature of ATP release from lung fibroblasts in response to mechanical and chemical stimuli.
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Affiliation(s)
- Kota Takahashi
- Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Satoru Ito
- Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan; Department of Respiratory Medicine and Allergology, Aichi Medical University, Nagakute 480-1195, Japan.
| | - Kishio Furuya
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Shuichi Asano
- Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Masahiro Sokabe
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Yoshinori Hasegawa
- Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
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82
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Suki B, Parameswaran H, Imsirovic J, Bartolák-Suki E. Regulatory Roles of Fluctuation-Driven Mechanotransduction in Cell Function. Physiology (Bethesda) 2017; 31:346-58. [PMID: 27511461 DOI: 10.1152/physiol.00051.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cells in the body are exposed to irregular mechanical stimuli. Here, we review the so-called fluctuation-driven mechanotransduction in which stresses stretching cells vary on a cycle-by-cycle basis. We argue that such mechanotransduction is an emergent network phenomenon and offer several potential mechanisms of how it regulates cell function. Several examples from the vasculature, the lung, and tissue engineering are discussed. We conclude with a list of important open questions.
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Affiliation(s)
- Béla Suki
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
| | | | - Jasmin Imsirovic
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
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83
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Cong X, Hubmayr RD, Li C, Zhao X. Plasma membrane wounding and repair in pulmonary diseases. Am J Physiol Lung Cell Mol Physiol 2017; 312:L371-L391. [PMID: 28062486 PMCID: PMC5374305 DOI: 10.1152/ajplung.00486.2016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/05/2017] [Accepted: 01/05/2017] [Indexed: 12/12/2022] Open
Abstract
Various pathophysiological conditions such as surfactant dysfunction, mechanical ventilation, inflammation, pathogen products, environmental exposures, and gastric acid aspiration stress lung cells, and the compromise of plasma membranes occurs as a result. The mechanisms necessary for cells to repair plasma membrane defects have been extensively investigated in the last two decades, and some of these key repair mechanisms are also shown to occur following lung cell injury. Because it was theorized that lung wounding and repair are involved in the pathogenesis of acute respiratory distress syndrome (ARDS) and idiopathic pulmonary fibrosis (IPF), in this review, we summarized the experimental evidence of lung cell injury in these two devastating syndromes and discuss relevant genetic, physical, and biological injury mechanisms, as well as mechanisms used by lung cells for cell survival and membrane repair. Finally, we discuss relevant signaling pathways that may be activated by chronic or repeated lung cell injury as an extension of our cell injury and repair focus in this review. We hope that a holistic view of injurious stimuli relevant for ARDS and IPF could lead to updated experimental models. In addition, parallel discussion of membrane repair mechanisms in lung cells and injury-activated signaling pathways would encourage research to bridge gaps in current knowledge. Indeed, deep understanding of lung cell wounding and repair, and discovery of relevant repair moieties for lung cells, should inspire the development of new therapies that are likely preventive and broadly effective for targeting injurious pulmonary diseases.
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Affiliation(s)
- Xiaofei Cong
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia
| | - Rolf D Hubmayr
- Emerius, Thoracic Diseases Research Unit, Mayo Clinic, Rochester, Minnesota; and
| | - Changgong Li
- Department of Pediatrics, University of Southern California, Los Angeles, California
| | - Xiaoli Zhao
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia;
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84
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Schwingshackl A. The role of stretch-activated ion channels in acute respiratory distress syndrome: finally a new target? Am J Physiol Lung Cell Mol Physiol 2016; 311:L639-52. [PMID: 27521425 DOI: 10.1152/ajplung.00458.2015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 08/05/2016] [Indexed: 02/06/2023] Open
Abstract
Mechanical ventilation (MV) and oxygen therapy (hyperoxia; HO) comprise the cornerstones of life-saving interventions for patients with acute respiratory distress syndrome (ARDS). Unfortunately, the side effects of MV and HO include exacerbation of lung injury by barotrauma, volutrauma, and propagation of lung inflammation. Despite significant improvements in ventilator technologies and a heightened awareness of oxygen toxicity, besides low tidal volume ventilation few if any medical interventions have improved ARDS outcomes over the past two decades. We are lacking a comprehensive understanding of mechanotransduction processes in the healthy lung and know little about the interactions between simultaneously activated stretch-, HO-, and cytokine-induced signaling cascades in ARDS. Nevertheless, as we are unraveling these mechanisms we are gathering increasing evidence for the importance of stretch-activated ion channels (SACs) in the activation of lung-resident and inflammatory cells. In addition to the discovery of new SAC families in the lung, e.g., two-pore domain potassium channels, we are increasingly assigning mechanosensing properties to already known Na(+), Ca(2+), K(+), and Cl(-) channels. Better insights into the mechanotransduction mechanisms of SACs will improve our understanding of the pathways leading to ventilator-induced lung injury and lead to much needed novel therapeutic approaches against ARDS by specifically targeting SACs. This review 1) summarizes the reasons why the time has come to seriously consider SACs as new therapeutic targets against ARDS, 2) critically analyzes the physiological and experimental factors that currently limit our knowledge about SACs, and 3) outlines the most important questions future research studies need to address.
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85
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Henriques I, Padilha GA, Huhle R, Wierzchon C, Miranda PJB, Ramos IP, Rocha N, Cruz FF, Santos RS, de Oliveira MV, Souza SA, Goldenberg RC, Luiz RR, Pelosi P, de Abreu MG, Silva PL, Rocco PRM. Comparison between Variable and Conventional Volume-Controlled Ventilation on Cardiorespiratory Parameters in Experimental Emphysema. Front Physiol 2016; 7:277. [PMID: 27445862 PMCID: PMC4928149 DOI: 10.3389/fphys.2016.00277] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/20/2016] [Indexed: 01/13/2023] Open
Abstract
Emphysema is characterized by loss of lung tissue elasticity and destruction of structures supporting alveoli and capillaries. The impact of mechanical ventilation strategies on ventilator-induced lung injury (VILI) in emphysema is poorly defined. New ventilator strategies should be developed to minimize VILI in emphysema. The present study was divided into two protocols: (1) characterization of an elastase-induced emphysema model in rats and identification of the time point of greatest cardiorespiratory impairment, defined as a high specific lung elastance associated with large right ventricular end-diastolic area; and (2) comparison between variable (VV) and conventional volume-controlled ventilation (VCV) on lung mechanics and morphometry, biological markers, and cardiac function at that time point. In the first protocol, Wistar rats (n = 62) received saline (SAL) or porcine pancreatic elastase (ELA) intratracheally once weekly for 4 weeks, respectively. Evaluations were performed 1, 3, 5, or 8 weeks after the last intratracheal instillation of saline or elastase. After identifying the time point of greatest cardiorespiratory impairment, an additional 32 Wistar rats were randomized into the SAL and ELA groups and then ventilated with VV or VCV (n = 8/group) [tidal volume (VT) = 6 mL/kg, positive end-expiratory pressure (PEEP) = 3 cmH2O, fraction of inspired oxygen (FiO2) = 0.4] for 2 h. VV was applied on a breath-to-breath basis as a sequence of randomly generated VT values (mean VT = 6 mL/kg), with a 30% coefficient of variation. Non-ventilated (NV) SAL and ELA animals were used for molecular biology analysis. The time point of greatest cardiorespiratory impairment, was observed 5 weeks after the last elastase instillation. At this time point, interleukin (IL)-6, cytokine-induced neutrophil chemoattractant (CINC)-1, amphiregulin, angiopoietin (Ang)-2, and vascular endothelial growth factor (VEGF) mRNA levels were higher in ELA compared to SAL. In ELA animals, VV reduced respiratory system elastance, alveolar collapse, and hyperinflation compared to VCV, without significant differences in gas exchange, but increased right ventricular diastolic area. Interleukin-6 mRNA expression was higher in VCV and VV than NV, while surfactant protein-D was increased in VV compared to NV. In conclusion, VV improved lung function and morphology and reduced VILI, but impaired right cardiac function in this model of elastase induced-emphysema.
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Affiliation(s)
- Isabela Henriques
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Gisele A Padilha
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Robert Huhle
- Pulmonary Engineering Group, Department of Anesthesiology and Intensive Care Therapy, University Hospital Carl Gustav Carus, Technische Universität Dresden Dresden, Germany
| | - Caio Wierzchon
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Paulo J B Miranda
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Isalira P Ramos
- Laboratory of Molecular and Cellular Cardiology, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de JaneiroRio de Janeiro, Brazil; National Center for Structural Biology and Bioimaging, Federal University of Rio de JaneiroRio de Janeiro, Brazil
| | - Nazareth Rocha
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de JaneiroRio de Janeiro, Brazil; Department of Physiology and Pharmacology, Biomedical Institute, Fluminense Federal UniversityNiterói, Brazil
| | - Fernanda F Cruz
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Raquel S Santos
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Milena V de Oliveira
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Sergio A Souza
- National Center for Structural Biology and Bioimaging, Federal University of Rio de JaneiroRio de Janeiro, Brazil; Nuclear Medicine Service, Clementino Fraga Filho University Hospital, Federal University of Rio de JaneiroRio de Janeiro, Brazil
| | - Regina C Goldenberg
- Laboratory of Molecular and Cellular Cardiology, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Ronir R Luiz
- Institute of Public Health Studies, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Paolo Pelosi
- Department of Surgical Sciences and Integrated Diagnostics, IRCCS AOU San Martino IST, University of Genoa Genoa, Italy
| | - Marcelo G de Abreu
- Pulmonary Engineering Group, Department of Anesthesiology and Intensive Care Therapy, University Hospital Carl Gustav Carus, Technische Universität Dresden Dresden, Germany
| | - Pedro L Silva
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Patricia R M Rocco
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
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Prakash YS, Tschumperlin DJ, Stenmark KR. Coming to terms with tissue engineering and regenerative medicine in the lung. Am J Physiol Lung Cell Mol Physiol 2015; 309:L625-38. [PMID: 26254424 DOI: 10.1152/ajplung.00204.2015] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 08/04/2015] [Indexed: 01/10/2023] Open
Abstract
Lung diseases such as emphysema, interstitial fibrosis, and pulmonary vascular diseases cause significant morbidity and mortality, but despite substantial mechanistic understanding, clinical management options for them are limited, with lung transplantation being implemented at end stages. However, limited donor lung availability, graft rejection, and long-term problems after transplantation are major hurdles to lung transplantation being a panacea. Bioengineering the lung is an exciting and emerging solution that has the ultimate aim of generating lung tissues and organs for transplantation. In this article we capture and review the current state of the art in lung bioengineering, from the multimodal approaches, to creating anatomically appropriate lung scaffolds that can be recellularized to eventually yield functioning, transplant-ready lungs. Strategies for decellularizing mammalian lungs to create scaffolds with native extracellular matrix components vs. de novo generation of scaffolds using biocompatible materials are discussed. Strengths vs. limitations of recellularization using different cell types of various pluripotency such as embryonic, mesenchymal, and induced pluripotent stem cells are highlighted. Current hurdles to guide future research toward achieving the clinical goal of transplantation of a bioengineered lung are discussed.
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Affiliation(s)
- Y S Prakash
- Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota;
| | - Daniel J Tschumperlin
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota; Division of Pulmonary Medicine, Mayo Clinic, Rochester, Minnesota; and
| | - Kurt R Stenmark
- Department of Pediatrics, University of Colorado, Aurora, Colorado
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87
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Mathematical model of a heterogeneous pulmonary acinus structure. Comput Biol Med 2015; 62:25-32. [PMID: 25912985 DOI: 10.1016/j.compbiomed.2015.03.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 03/02/2015] [Accepted: 03/31/2015] [Indexed: 01/06/2023]
Abstract
The pulmonary acinus is a gas exchange unit distal to the terminal bronchioles. A model of its structure is important for the computational investigation of mechanical phenomena at the acinus level. We propose a mathematical model of a heterogeneous acinus structure composed of alveoli of irregular sizes, shapes, and locations. The alveoli coalesce into an intricately branched ductal tree, which meets the space-filling requirement of the acinus structure. Our model uses Voronoi tessellation to generate an assemblage of the alveolar or ductal airspace, and Delaunay tessellation and simulated annealing for the ductal tree structure. The modeling condition is based on average acinar and alveolar volume characteristics from published experimental information. By applying this modeling technique to the acinus of healthy mature rats, we demonstrate that the proposed acinus structure model reproduces the available experimental information. In the model, the shape and size of alveoli and the length, generation, tortuosity, and branching angle of the ductal paths are distributed in several ranges. This approach provides a platform for investigating the heterogeneous nature of the acinus structure and its relationship with mechanical phenomena at the acinus level.
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88
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Tahamtan R, Shabestani Monfared A, Tahamtani Y, Tavassoli A, Akmali M, Mosleh-Shirazi MA, Naghizadeh MM, Ghasemi D, Keshavarz M, Haddadi GH. Radioprotective effect of melatonin on radiation-induced lung injury and lipid peroxidation in rats. CELL JOURNAL 2015; 17:111-20. [PMID: 25870840 PMCID: PMC4393658 DOI: 10.22074/cellj.2015.517] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Accepted: 02/26/2014] [Indexed: 01/21/2023]
Abstract
Objective Free radicals generated by ionizing radiation attack various cellular components such as lipids. The lung is a very radiosensitive organ and its damage is a doselimiting factor in radiotherapy treatments. Melatonin (MLT), the major product of the pineal
gland acts as a radioprotective agent. This study aims to investigate the radioprotective
effects of MLT on malondialdehyde (MDA) levels and histopathological changes in irradiated lungs.
Materials and Methods In this experimental study, a total of 62 rats were divided into
five groups. Group 1 received no MLT and radiation (unT), group 2 received oral MLT
(oM), group 3 received oral MLT and their thoracic areas were irradiated with 18 Gy (oMR), group 4 received MLT by intraperitoneal (i.p.) injection and their thoracic areas were
irradiated with 18 Gy (ipM-R), group 5 received only 18 Gy radiation in the thoracic area
(R). Following radiotherapy, half of the animals in each group were sacrificed at 48 hours
for evaluation of lipid peroxidation and early phase lung injuries. Other animals were sacrificed in the eighth week of the experiment for evaluation of the presence of late phase
radiation induced lung injuries.
Results Pre-treatment of rats with either i.p injection (p<0.05) and oral administration of
MLT (p<0.001) significantly reduced MDA levels in red blood cell (RBC) samples compared to the R group. Furthermore, i.p. injection of MLT decreased MDA levels in plasma
and tissue (p<0.05). In the early phase of lung injury, both administration of MLT significantly increased lymphocyte (p<0.05) and macrophage frequency (p<0.001). MLT reduced the lung injury index in the lungs compared to the R group (p<0.05).
Conclusion The result of this study confirms the radioprotective effect of MLT on lipid
peroxidation, and in both early and late phases of radiation induced lung injuries in an
animal model.
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Affiliation(s)
- Raziyeh Tahamtan
- Department of Biophysics and Biochemistry, Cellular and Molecular Biology Research Centre, Babol University of Medical Sciences, Babol, Iran
| | - Ali Shabestani Monfared
- Department of Biophysics and Biochemistry, Cellular and Molecular Biology Research Centre, Babol University of Medical Sciences, Babol, Iran
| | - Yasser Tahamtani
- Department of Stem Cells and Developmental Biology at Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Alireza Tavassoli
- Department of Pathology, Fasa University of Medical Sciences, Fasa, Iran
| | - Maasoomeh Akmali
- Department of Biochemistry, Faculty of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | | | | | - Danial Ghasemi
- Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mojtaba Keshavarz
- Young Researchers and Elite Club, Shiraz Branch, Islamic Azad University of Shiraz, Shiraz Iran
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Modulation of stress versus time product during mechanical ventilation influences inflammation as well as alveolar epithelial and endothelial response in rats. Anesthesiology 2015; 122:106-16. [PMID: 25141026 DOI: 10.1097/aln.0000000000000415] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND Mechanical ventilation can lead to lung biotrauma when mechanical stress exceeds safety thresholds. The authors investigated whether the duration of mechanical stress, that is, the impact of a stress versus time product (STP), influences biotrauma. The authors hypothesized that higher STP levels are associated with increased inflammation and with alveolar epithelial and endothelial cell injury. METHODS In 46 rats, Escherichia coli lipopolysaccharide (acute lung inflammation) or saline (control) was administered intratracheally. Both groups were protectively ventilated with inspiratory-to-expiratory ratios 1:2, 1:1, or 2:1 (n = 12 each), corresponding to low, middle, and high STP levels (STPlow, STPmid, and STPhigh, respectively). The remaining 10 animals were not mechanically ventilated. RESULTS In animals with mild acute lung inflammation, but not in controls: (1) messenger RNA expression of interleukin-6 was higher in STPhigh (28.1 ± 13.6; mean ± SD) and STPlow (28.9 ± 16.0) versus STPmid (7.4 ± 7.5) (P < 0.05); (2) expression of the receptor for advanced glycation end-products was increased in STPhigh (3.6 ± 1.6) versus STPlow (2.3 ± 1.1) (P < 0.05); (3) alveolar edema was decreased in STPmid (0 [0 to 0]; median, Q1 to Q3) compared with STPhigh (0.8 [0.6 to 1]) (P < 0.05); and (4) expressions of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 were higher in STPlow (3.0 ± 1.8) versus STPhigh (1.2 ± 0.5) and STPmid (1.4 ± 0.7) (P < 0.05), respectively. CONCLUSIONS In the mild acute lung inflammation model used herein, mechanical ventilation with inspiratory-to-expiratory of 1:1 (STPmid) minimized lung damage, whereas STPhigh increased the gene expression of biological markers associated with inflammation and alveolar epithelial cell injury and STPlow increased markers of endothelial cell damage.
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90
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Chang S, Kwon N, Kim J, Kohmura Y, Ishikawa T, Rhee CK, Je JH, Tsuda A. Synchrotron X-ray imaging of pulmonary alveoli in respiration in live intact mice. Sci Rep 2015; 5:8760. [PMID: 25737245 PMCID: PMC4348649 DOI: 10.1038/srep08760] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 02/03/2015] [Indexed: 12/29/2022] Open
Abstract
Despite nearly a half century of studies, it has not been fully understood how pulmonary alveoli, the elementary gas exchange units in mammalian lungs, inflate and deflate during respiration. Understanding alveolar dynamics is crucial for treating patients with pulmonary diseases. In-vivo, real-time visualization of the alveoli during respiration has been hampered by active lung movement. Previous studies have been therefore limited to alveoli at lung apices or subpleural alveoli under open thorax conditions. Here we report direct and real-time visualization of alveoli of live intact mice during respiration using tracking X-ray microscopy. Our studies, for the first time, determine the alveolar size of normal mice in respiration without positive end expiratory pressure as 58 ± 14 (mean ± s.d.) μm on average, accurately measured in the lung bases as well as the apices. Individual alveoli of normal lungs clearly show heterogeneous inflation from zero to ~25% (6.7 ± 4.7% (mean ± s.d.)) in size. The degree of inflation is higher in the lung bases (8.7 ± 4.3% (mean ± s.d.)) than in the apices (5.7 ± 3.2% (mean ± s.d.)). The fraction of the total tidal volume allocated for alveolar inflation is 34 ± 3.8% (mean ± s.e.m). This study contributes to the better understanding of alveolar dynamics and helps to develop potential treatment options for pulmonary diseases.
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Affiliation(s)
- Soeun Chang
- 1] X-ray Imaging Center, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang, 790-784, Korea [2] Department of Materials Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang, 790-784, Korea
| | - Namseop Kwon
- 1] X-ray Imaging Center, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang, 790-784, Korea [2] School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang, 790-784, Korea
| | - Jinkyung Kim
- X-ray Imaging Center, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang, 790-784, Korea
| | - Yoshiki Kohmura
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo, Hyogo, 679-5198, Japan
| | - Tetsuya Ishikawa
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo, Hyogo, 679-5198, Japan
| | - Chin Kook Rhee
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul St. Mary's Hospital, Catholic University of Korea, 505 Banpo-dong, Seocho-Gu, Seoul, 137-701, Korea
| | - Jung Ho Je
- 1] X-ray Imaging Center, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang, 790-784, Korea [2] Department of Materials Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang, 790-784, Korea [3] RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo, Hyogo, 679-5198, Japan
| | - Akira Tsuda
- Harvard School of Public Health, Boston, Massachusetts, USA
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91
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Tenenbaum-Katan J, Fishler R, Rothen-Rutishauser B, Sznitman J. Biomimetics of fetal alveolar flow phenomena using microfluidics. BIOMICROFLUIDICS 2015; 9:014120. [PMID: 25759753 PMCID: PMC4336252 DOI: 10.1063/1.4908269] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 01/23/2015] [Indexed: 05/12/2023]
Abstract
At the onset of life in utero, the respiratory system begins as a liquid-filled tubular organ and undergoes significant morphological changes during fetal development towards establishing a respiratory organ optimized for gas exchange. As airspace morphology evolves, respiratory alveolar flows have been hypothesized to exhibit evolving flow patterns. In the present study, we have investigated flow topologies during increasing phases of embryonic life within an anatomically inspired microfluidic device, reproducing real-scale features of fetal airways representative of three distinct phases of in utero gestation. Micro-particle image velocimetry measurements, supported by computational fluid dynamics simulations, reveal distinct respiratory alveolar flow patterns throughout different stages of fetal life. While attached, streamlined flows characterize the shallow structures of premature alveoli indicative of the onset of saccular stage, separated recirculating vortex flows become the signature of developed and extruded alveoli characteristic of the advanced stages of fetal development. To further mimic physiological aspects of the cellular environment of developing airways, our biomimetic devices integrate an alveolar epithelium using the A549 cell line, recreating a confluent monolayer that produces pulmonary surfactant. Overall, our in vitro biomimetic fetal airways model delivers a robust and reliable platform combining key features of alveolar morphology, flow patterns, and physiological aspects of fetal lungs developing in utero.
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Affiliation(s)
- Janna Tenenbaum-Katan
- Department of Biomedical Engineering, Technion-Israel Institute of Technology , 32000 Haifa, Israel
| | - Rami Fishler
- Department of Biomedical Engineering, Technion-Israel Institute of Technology , 32000 Haifa, Israel
| | | | - Josué Sznitman
- Department of Biomedical Engineering, Technion-Israel Institute of Technology , 32000 Haifa, Israel
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92
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D'Angio CT, Ryan RM. Animal models of bronchopulmonary dysplasia. The preterm and term rabbit models. Am J Physiol Lung Cell Mol Physiol 2014; 307:L959-69. [PMID: 25326582 DOI: 10.1152/ajplung.00228.2014] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Bronchopulmonary dysplasia (BPD) is an important lung developmental pathophysiology that affects many premature infants each year. Newborn animal models employing both premature and term animals have been used over the years to study various components of BPD. This review describes some of the neonatal rabbit studies that have contributed to the understanding of BPD, including those using term newborn hyperoxia exposure models, premature hyperoxia models, and a term newborn hyperoxia model with recovery in moderate hyperoxia, all designed to emulate aspects of BPD in human infants. Some investigators perturbed these models to include exposure to neonatal infection/inflammation or postnatal malnutrition. The similarities to lung injury in human premature infants include an acute inflammatory response with the production of cytokines, chemokines, and growth factors that have been implicated in human disease, abnormal pulmonary function, disordered lung architecture, and alveolar simplification, development of fibrosis, and abnormal vascular growth factor expression. Neonatal rabbit models have the drawback of limited access to reagents as well as the lack of readily available transgenic models but, unlike smaller rodent models, are able to be manipulated easily and are significantly less expensive than larger animal models.
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Affiliation(s)
- Carl T D'Angio
- Department of Pediatrics, University of Rochester Medical Center, Rochester, New York and
| | - Rita M Ryan
- Department of Pediatrics, Medical University of South Carolina, Charleston, South Carolina
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93
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Murata N, Ito S, Furuya K, Takahara N, Naruse K, Aso H, Kondo M, Sokabe M, Hasegawa Y. Ca2+ influx and ATP release mediated by mechanical stretch in human lung fibroblasts. Biochem Biophys Res Commun 2014; 453:101-5. [PMID: 25256743 DOI: 10.1016/j.bbrc.2014.09.063] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 09/16/2014] [Indexed: 01/31/2023]
Abstract
One cause of progressive pulmonary fibrosis is dysregulated wound healing after lung inflammation or damage in patients with idiopathic pulmonary fibrosis and severe acute respiratory distress syndrome. The mechanical forces are considered to regulate pulmonary fibrosis via activation of lung fibroblasts. In this study, the effects of mechanical stretch on the intracellular Ca(2+) concentration ([Ca(2+)]i) and ATP release were investigated in primary human lung fibroblasts. Uniaxial stretch (10-30% in strain) was applied to fibroblasts cultured in a silicone chamber coated with type I collagen using a stretching apparatus. Following stretching and subsequent unloading, [Ca(2+)]i transiently increased in a strain-dependent manner. Hypotonic stress, which causes plasma membrane stretching, also transiently increased the [Ca(2+)]i. The stretch-induced [Ca(2+)]i elevation was attenuated in Ca(2+)-free solution. In contrast, the increase of [Ca(2+)]i by a 20% stretch was not inhibited by the inhibitor of stretch-activated channels GsMTx-4, Gd(3+), ruthenium red, or cytochalasin D. Cyclic stretching induced significant ATP releases from fibroblasts. However, the stretch-induced [Ca(2+)]i elevation was not inhibited by ATP diphosphohydrolase apyrase or a purinergic receptor antagonist suramin. Taken together, mechanical stretch induces Ca(2+) influx independently of conventional stretch-sensitive ion channels, the actin cytoskeleton, and released ATP.
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Affiliation(s)
- Naohiko Murata
- Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Satoru Ito
- Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
| | - Kishio Furuya
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Norihiro Takahara
- Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Keiji Naruse
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Okayama 700-8558, Japan
| | - Hiromichi Aso
- Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Masashi Kondo
- Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Masahiro Sokabe
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Yoshinori Hasegawa
- Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
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Kollisch-Singule M, Emr B, Smith B, Ruiz C, Roy S, Meng Q, Jain S, Satalin J, Snyder K, Ghosh A, Marx WH, Andrews P, Habashi N, Nieman GF, Gatto LA. Airway pressure release ventilation reduces conducting airway micro-strain in lung injury. J Am Coll Surg 2014; 219:968-76. [PMID: 25440027 DOI: 10.1016/j.jamcollsurg.2014.09.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 07/25/2014] [Accepted: 08/01/2014] [Indexed: 12/18/2022]
Abstract
BACKGROUND Improper mechanical ventilation can exacerbate acute lung damage, causing a secondary ventilator-induced lung injury (VILI). We hypothesized that VILI can be reduced by modifying specific components of the ventilation waveform (mechanical breath), and we studied the impact of airway pressure release ventilation (APRV) and controlled mandatory ventilation (CMV) on the lung micro-anatomy (alveoli and conducting airways). The distribution of gas during inspiration and expiration and the strain generated during mechanical ventilation in the micro-anatomy (micro-strain) were calculated. STUDY DESIGN Rats were anesthetized, surgically prepared, and randomized into 1 uninjured control group (n = 2) and 4 groups with lung injury: APRV 75% (n = 2), time at expiration (TLow) set to terminate appropriately at 75% of peak expiratory flow rate (PEFR); APRV 10% (n = 2), TLow set to terminate inappropriately at 10% of PEFR; CMV with PEEP 5 cm H2O (PEEP 5; n = 2); or PEEP 16 cm H2O (PEEP 16; n = 2). Lung injury was induced in the experimental groups by Tween lavage and ventilated with their respective settings. Lungs were fixed at peak inspiration and end expiration for standard histology. Conducting airway and alveolar air space areas were quantified and conducting airway micro-strain was calculated. RESULTS All lung injury groups redistributed inspired gas away from alveoli into the conducting airways. The APRV 75% minimized gas redistribution and micro-strain in the conducting airways and provided the alveolar air space occupancy most similar to control at both inspiration and expiration. CONCLUSIONS In an injured lung, APRV 75% maintained micro-anatomic gas distribution similar to that of the normal lung. The lung protection demonstrated in previous studies using APRV 75% may be due to a more homogeneous distribution of gas at the micro-anatomic level as well as a reduction in conducting airway micro-strain.
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Affiliation(s)
| | - Bryanna Emr
- Department of General Surgery, SUNY Upstate Medical University, Syracuse, NY
| | - Bradford Smith
- Department of Medicine, University of Vermont, Burlington, VT
| | - Cynthia Ruiz
- Department of Biological Sciences, SUNY Cortland, Cortland, NY
| | - Shreyas Roy
- Department of General Surgery, SUNY Upstate Medical University, Syracuse, NY
| | - Qinghe Meng
- Department of General Surgery, SUNY Upstate Medical University, Syracuse, NY
| | - Sumeet Jain
- Department of General Surgery, SUNY Upstate Medical University, Syracuse, NY
| | - Joshua Satalin
- Department of General Surgery, SUNY Upstate Medical University, Syracuse, NY.
| | - Kathy Snyder
- Department of General Surgery, SUNY Upstate Medical University, Syracuse, NY
| | - Auyon Ghosh
- Department of General Surgery, SUNY Upstate Medical University, Syracuse, NY
| | - William H Marx
- Department of General Surgery, SUNY Upstate Medical University, Syracuse, NY
| | - Penny Andrews
- R Adams Cowley Shock Trauma Center, Trauma Critical Care Medicine, University of Maryland School of Medicine, Baltimore, MD
| | - Nader Habashi
- R Adams Cowley Shock Trauma Center, Trauma Critical Care Medicine, University of Maryland School of Medicine, Baltimore, MD
| | - Gary F Nieman
- Department of General Surgery, SUNY Upstate Medical University, Syracuse, NY
| | - Louis A Gatto
- Department of General Surgery, SUNY Upstate Medical University, Syracuse, NY; Department of Biological Sciences, SUNY Cortland, Cortland, NY
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Perchiazzi G, Rylander C, Derosa S, Pellegrini M, Pitagora L, Polieri D, Vena A, Tannoia A, Fiore T, Hedenstierna G. Regional distribution of lung compliance by image analysis of computed tomograms. Respir Physiol Neurobiol 2014; 201:60-70. [PMID: 25026158 DOI: 10.1016/j.resp.2014.07.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/01/2014] [Accepted: 07/02/2014] [Indexed: 10/25/2022]
Abstract
Computed tomography (CT) can yield quantitative information about volume distribution in the lung. By combining information provided by CT and respiratory mechanics, this study aims at quantifying regional lung compliance (CL) and its distribution and homogeneity in mechanically ventilated pigs. The animals underwent inspiratory hold maneuvers at 12 lung volumes with simultaneous CT exposure at two end-expiratory pressure levels and before and after acute lung injury (ALI) by oleic acid administration. CL and the sum of positive voxel compliances from CT were linearly correlated; negative compliance areas were found. A remarkably heterogeneous distribution of voxel compliance was found in the injured lungs. As the lung inflation increased, the homogeneity increased in healthy lungs but decreased in injured lungs. Image analysis brought novel findings regarding spatial homogeneity of compliance, which increases in ALI but not in healthy lungs by applying PEEP after a recruitment maneuver.
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Affiliation(s)
- Gaetano Perchiazzi
- Emergency and Organ Transplant, Bari University, Bari, Italy; Medical Sciences - Clinical Physiology, Uppsala University, Uppsala, Sweden.
| | - Christian Rylander
- Anaesthesia and Intensive Care Medicine, Sahlgrenska University Hospital, Göteborg, Sweden
| | - Savino Derosa
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | | | | | - Debora Polieri
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Antonio Vena
- Intensive Care Unit, SS Annunziata Hospital, Taranto, Italy
| | - Angela Tannoia
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Tommaso Fiore
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Göran Hedenstierna
- Medical Sciences - Clinical Physiology, Uppsala University, Uppsala, Sweden
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96
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Chen ZL, Chen YZ, Hu ZY. A micromechanical model for estimating alveolar wall strain in mechanically ventilated edematous lungs. J Appl Physiol (1985) 2014; 117:586-92. [PMID: 24947025 DOI: 10.1152/japplphysiol.00072.2014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To elucidate the micromechanics of pulmonary edema has been a significant medical concern, which is beneficial to better guide ventilator settings in clinical practice. In this paper, we present an adjoining two-alveoli model to quantitatively estimate strain and stress of alveolar walls in mechanically ventilated edematous lungs. The model takes into account the geometry of the alveolus, the effect of surface tension, the length-tension properties of parenchyma tissue, and the change in thickness of the alveolar wall. On the one hand, our model supports experimental findings (Perlman CE, Lederer DJ, Bhattacharya J. Am J Respir Cell Mol Biol 44: 34-39, 2011) that the presence of a liquid-filled alveolus protrudes into the neighboring air-filled alveolus with the shared septal strain amounting to a maximum value of 1.374 (corresponding to the maximum stress of 5.12 kPa) even at functional residual capacity; on the other hand, it further shows that the pattern of alveolar expansion appears heterogeneous or homogeneous, strongly depending on differences in air-liquid interface tension on alveolar segments. The proposed model is a preliminary step toward picturing a global topographical distribution of stress and strain on the scale of the lung as a whole to prevent ventilator-induced lung injury.
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Affiliation(s)
- Zheng-long Chen
- Biomedical Instrument Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China; and Department of Precise Medical Device, Shanghai Medical Instrumentation College, Shanghai, China
| | - Ya-zhu Chen
- Biomedical Instrument Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China; and
| | - Zhao-yan Hu
- Department of Precise Medical Device, Shanghai Medical Instrumentation College, Shanghai, China
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97
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Santos CL, Moraes L, Santos RS, dos Santos Samary C, Silva JD, Morales MM, Capelozzi VL, de Abreu MG, Schanaider A, Silva PL, Garcia CSNB, Pelosi P, Rocco PRM. The biological effects of higher and lower positive end-expiratory pressure in pulmonary and extrapulmonary acute lung injury with intra-abdominal hypertension. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2014; 18:R121. [PMID: 24928415 PMCID: PMC4095606 DOI: 10.1186/cc13920] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 05/27/2014] [Indexed: 01/01/2023]
Abstract
Introduction Mechanical ventilation with high positive end-expiratory pressure (PEEP) has been used in patients with acute respiratory distress syndrome (ARDS) and intra-abdominal hypertension (IAH), but the role of PEEP in minimizing lung injury remains controversial. We hypothesized that in the presence of acute lung injury (ALI) with IAH: 1) higher PEEP levels improve pulmonary morphofunction and minimize lung injury; and 2) the biological effects of higher PEEP are more effective in extrapulmonary (exp) than pulmonary (p) ALI. Methods In 48 adult male Wistar rats, ALIp and ALIexp were induced by Escherichia coli lipopolysaccharide intratracheally and intraperitoneally, respectively. After 24 hours, animals were anesthetized and mechanically ventilated (tidal volume of 6 mL/kg). IAH (15 mmHg) was induced and rats randomly assigned to PEEP of 5 (PEEP5), 7 (PEEP7) or 10 (PEEP10) cmH2O for 1 hour. Results In both ALIp and ALIexp, higher PEEP levels improved oxygenation. PEEP10 increased alveolar hyperinflation and epithelial cell damage compared to PEEP5, independent of ALI etiology. In ALIp, PEEP7 and PEEP10 increased lung elastance compared to PEEP5 (4.3 ± 0.7 and 4.3 ± 0.9 versus 3.1 ± 0.3 cmH2O/mL, respectively, P <0.01), without changes in alveolar collapse, interleukin-6, caspase-3, type III procollagen, receptor for advanced glycation end-products, and vascular cell adhesion molecule-1 expressions. Moreover, PEEP10 increased diaphragmatic injury compared to PEEP5. In ALIexp, PEEP7 decreased lung elastance and alveolar collapse compared to PEEP5 (2.3 ± 0.5 versus 3.6 ± 0.7 cmH2O/mL, P <0.02, and 27.2 (24.7 to 36.8) versus 44.2 (39.7 to 56.9)%, P <0.05, respectively), while PEEP7 and PEEP10 increased interleukin-6 and type III procollagen expressions, as well as type II epithelial cell damage compared to PEEP5. Conclusions In the current models of ALI with IAH, in contrast to our primary hypothesis, higher PEEP is more effective in ALIp than ALIexp as demonstrated by the activation of biological markers. Therefore, higher PEEP should be used cautiously in the presence of IAH and ALI, mainly in ALIexp.
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98
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Theoretical calculation of bending stiffness of alveolar wall. J Membr Biol 2014; 246:981-4. [PMID: 24121628 DOI: 10.1007/s00232-013-9602-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 09/27/2013] [Indexed: 10/26/2022]
Abstract
The bending stiffness of the alveolar wall is theoretically analyzed in this study through analytical modeling. First, the alveolar wall facet and its characteristics were geometrically simplified and then modeled using known physical laws. Bending stiffness is shown to be dependent on alveolar wall thickness, density, Poisson's ratio and speed of the longitudinal wave. The normal bending stiffness of the alveolar wall was further determined. For the adult human, the normal bending stiffness is calculated to be 71.0-414.7 nNm, while for the adult mouse it is 1.9-30.0 nNm. The results of this study can be used as a reference for future pulmonary emphysema and fibrosis studies, as the bending stiffness of alveolar wall will be lower and higher, respectively; than the theoretically determined normal values.
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99
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Cressoni M, Cadringher P, Chiurazzi C, Amini M, Gallazzi E, Marino A, Brioni M, Carlesso E, Chiumello D, Quintel M, Bugedo G, Gattinoni L. Lung inhomogeneity in patients with acute respiratory distress syndrome. Am J Respir Crit Care Med 2014; 189:149-58. [PMID: 24261322 DOI: 10.1164/rccm.201308-1567oc] [Citation(s) in RCA: 184] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
RATIONALE Pressures and volumes needed to induce ventilator-induced lung injury in healthy lungs are far greater than those applied in diseased lungs. A possible explanation may be the presence of local inhomogeneities acting as pressure multipliers (stress raisers). OBJECTIVES To quantify lung inhomogeneities in patients with acute respiratory distress syndrome (ARDS). METHODS Retrospective quantitative analysis of CT scan images of 148 patients with ARDS and 100 control subjects. An ideally homogeneous lung would have the same expansion in all regions; lung expansion was measured by CT scan as gas/tissue ratio and lung inhomogeneities were measured as lung regions with lower gas/tissue ratio than their neighboring lung regions. We defined as the extent of lung inhomogeneities the fraction of the lung showing an inflation ratio greater than 95th percentile of the control group (1.61). MEASUREMENTS AND MAIN RESULTS The extent of lung inhomogeneities increased with the severity of ARDS (14 ± 5, 18 ± 8, and 23 ± 10% of lung volume in mild, moderate, and severe ARDS; P < 0.001) and correlated with the physiologic dead space (r(2) = 0.34; P < 0.0001). The application of positive end-expiratory pressure reduced the extent of lung inhomogeneities from 18 ± 8 to 12 ± 7% (P < 0.0001) going from 5 to 45 cm H2O airway pressure. Lung inhomogeneities were greater in nonsurvivor patients than in survivor patients (20 ± 9 vs. 17 ± 7% of lung volume; P = 0.01) and were the only CT scan variable independently associated with mortality at backward logistic regression. CONCLUSIONS Lung inhomogeneities are associated with overall disease severity and mortality. Increasing the airway pressures decreased but did not abolish the extent of lung inhomogeneities.
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Affiliation(s)
- Massimo Cressoni
- 1 Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Fondazione IRCCS Ca' Granda-Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy
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Larsson M, Larsson K. Periodic minimal surface organizations of the lipid bilayer at the lung surface and in cubic cytomembrane assemblies. Adv Colloid Interface Sci 2014; 205:68-73. [PMID: 23910375 DOI: 10.1016/j.cis.2013.07.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 06/29/2013] [Accepted: 07/11/2013] [Indexed: 11/24/2022]
Abstract
The existence of infinite periodic lipid bilayer structures in biological systems was first demonstrated in cell membrane assemblies. Such periodicity is only possible in symmetric bilayers, and their occurrence is discussed here in relation to the asymmetry of cell membranes in vivo. A periodic membrane conformation in the prolamellar body of plants corresponds to a dormant state without photosynthesis. A similar reversible formation of a dormant state has also been observed in the mitochondria of the amoeba Chaos. In these cases the energy production has become insufficient to maintain the membrane asymmetry. Formation of membranes that are symmetric over the bilayer is proposed to be a principal mechanism behind formation of cubic membrane systems. Another type of bicontinuous minimal surface structure is considered to form the alveolar lining of mammals at normal breathing conditions. The CLP surface corresponds to such a tetragonal surface phase. It is also a symmetric bilayer and in a state of zero energy expenditure. Structural alternatives of the bilayer conformation in this latter system are also discussed here.
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