Unit Of Lung Research Articles

Multilineage murine stem cells generate complex organoids to model distal lung development and disease

Organoids derived from mouse and human stem cells have recently emerged as a powerful tool to study organ development and disease. We here established a three‐dimensional (3D) murine bronchioalveolar lung organoid (BALO) model that allows clonal expansion and self‐organization of FACS‐sorted bronchioalveolar stem cells (BASCs) upon co‐culture with lung‐resident mesenchymal cells. BALOs yield a highly branched 3D structure within 21 days of culture, mimicking the cellular composition of the bronchioalveolar compartment as defined by single‐cell RNA sequencing and fluorescence as well as electron microscopic phenotyping. Additionally, BALOs support engraftment and maintenance of the cellular phenotype of injected tissue‐resident macrophages. We also demonstrate that BALOs recapitulate lung developmental defects after knockdown of a critical regulatory gene, and permit modeling of viral infection. We conclude that the BALO model enables reconstruction of the epithelial–mesenchymal‐myeloid unit of the distal lung, thereby opening numerous new avenues to study lung development, infection, and regenerative processes in vitro.

Effective segmentation of fresh post-mortem murine lung parenchyma in phase contrast X-ray tomographic microscopy images

The acinus represents the functional unit of the mammalian lung. It is defined as the small tree of gas-exchanging airways, which is fed by the most distal purely conducting airway. Different hypotheses exist on how the fine structure of the acinus changes during ventilation and development. Since in classical 2-dimensional (2D) sections of the lung the borders of the acini are not detectable, every study of acini requires 3-dimensional (3D) datasets. As a basis for further studies of pulmonary acini we imaged rodent lungs as close to life as possible using phase contrast synchrotron radiation-based X-ray tomographic microscopy (SRXTM), and developed a protocol for the segmentation of the alveolar septa. The method is based on a combined multilevel filtering approach. Seeds are automatically defined for separate regions of tissue and airspace during each 2D filtering level and then given as input to a 3D random walk segmentation. Thus, the different types of artifacts present in the images are treated separately, taking into account the sample’s structural complexity. The proposed procedure yields high-quality 3D segmentations of acinar microstructure that can be used for a reliable morphological analysis.

In vitro and in vivo antifungal activity of Cassia surattensis flower against Aspergillus niger

Invasive aspergillosis (IA) in immunocompromised host is a major infectious disease leading to reduce the survival rate of world population. Aspergillus niger is a causative agent causing IA. Cassia surattensis plant is commonly used in rural areas to treat various types of disease. C. surattensis flower extract was evaluated against the systemic aspergillosis model in this study. Qualitative measurement of fungal burden suggested a reduction pattern in the colony forming unit (CFU) of lung, liver, spleen and kidney for the extract treated group. Galactomannan assay assessment showed a decrease of fungal load in the treatment and positive control group with galactomannan index (GMI) value of 1.27 and 0.25 on day 28 but the negative control group showed high level of galactomannan in the serum with GMI value of 3.58. Histopathology examinations of the tissues featured major architecture modifications in the tissues of negative control group. Tissue reparation and recovery from infection were detected in extract treated and positive control group. Time killing fungicidal study of A. niger revealed dependence of the concentration of C. surattensis flower extract.

A Pathologist’s View of Airway Obstruction in Chronic Obstructive Pulmonary Disease

The boundary between purely conducting airways and gas exchanging tissue is formed by the terminal bronchioles as they divide into transitional bronchioles where alveolar openings first appear (1). The numbers of alveolar openings increase with each successive generation of branching until they take up the entire luminal surface in the alveolar ducts and the ducts branch for several more generations before ending blindly in alveolar sacs (2). McDonough and colleagues recently used a combination of multidetector computed tomography (MDCT) and micro-CT to show that there are about 44,510 ± 15,574 (± SD) terminal bronchioles/lung pair (3), a number that compares favorably to a mean of 44,500 ± 18,574 (± SD) obtained in four separate studies of individual lung casts (1, 4–6). Each terminal bronchiole supplies a unit of lung termed the acinus, and a secondary lobule refers to a group of acini that are either surrounded by a connective tissue septum (Figure 1A) when examined by histology (2), or where bronchioles cluster only millimeters apart (Figure 1B) when examined in a bronchogram (7).

Research at the Unit of Lung and Allergy research at Karolinksa Intitutet, Stockholm, Sweden

In 2002, the Unit of Lung and Allergy Research moved from the National Institute for Working Life, which was a government research institute separate from the university, to the National Institute of Environmental Medicine at the Karolinska Institutet, which is the medical university of Stockholm, Sweden. The Unit of Lung and Allergy Research group was established at the beginning of the 1980s under the guidance of Professor Per Malmberg and the main interest at that time was within respiratory physiology. At the beginning of the 1990s, the focus changed and became more concentrated on airway inflammatory mechanisms in respiratory diseases, especially as a consequence of exposure to organic material. It was soon established that exposure in pig barns constitutes a very powerful pro-inflammatory stimulus [1, 2], which enabled us to use exposure to organic dust from pig barns as a model for induction of inflammatory reactions. During the past 15 yrs, ∼60 original publications based on in vivo and in vitro experiments of the pro-inflammatory effects of exposure to organic dust and gases from swine confinement buildings have been published. Six PhD students have defended their theses based on the model and two PhD students are presently working with different aspects of it. After having demonstrated that working for some hours in a pig house causes an intense airway inflammatory reaction and an increase of bronchial responsiveness to methacholine of three to four …

Winners of the ERS Annual Awards 2007

The European Respiratory Review (ERR) is delighted to publish articles from the winners of the European Respiratory Society Annual Awards 2007. The awardees were invited to include the background to their work, how they thought it might be important to respiratory medicine, the aims of the team in which they work and, finally, to include their award-winning abstract. The present issue of the ERR includes the first section of awardee articles; the second section will appear in the next issue of the ERR . The following articles encompass a spectrum of research and provide an insight into work being carried out around the world today. The first section begins with Professor Kjell Larsson's synopsis of the research taking place in the Unit of Lung and Allergy Research at the Karolinksa Intitutet, Sweden (page 15), which he is head of. The unit is particularly interested in innate immunity in pigs, acquired immunity in furred animals, smoking in chronic obstructive pulmonary disease (COPD) and epidemiological studies of obstructive lung disease. Professor Jonathan Grigg's primary research focus concerns children's exposure to locally derived particulate pollution, which led to his paper on “Carbon in airway macrophages and lung function in children” (page 18). He found an inverse association between alveolar macrophages carbon and lung function, and a positive association between modelled exposure to primary particles and alveolar macrophage carbon. Dr Neeta Kulkarni, a clinical research fellow attached to Professor Grigg's project, has developed the technique of assessing exposure to indoor air pollution in the developing world. In her project …

In vivo assessment of alveolar morphology using a flexible catheter-based confocal microscope

Investigating the structure and function of alveoli in vivo is crucial for understanding the normal and diseased lungs. The authors image the alveoli of mice in vivo using a custom fibre optic catheter-based laser scanning confocal microscope. Images obtained using this system are analysed with an automated software application for alveolar size, wall thickness and number. Results show that direct dynamic visualisation of alveoli and surrounding structures is possible in vivo, with high resolution. Early results indicate high heterogeneity in alveolar structure in vivo, as opposed to an ordered uniform structure. Using the techniques presented here, there is great promise for advancing our knowledge of the functional unit of the lung, the alveolus, for alveolar mechanics, cell traffic and three-dimensional structural visualisation.

A MODEL LUNG WITH DIRECT REPRESENTATION OF RESPIRATORY MUSCLE ACTIVITY

We describe the theory, construction and testing of an active model lung. This is designed so that when it is connected to a ventilator, the interaction between spontaneous ventilatory activity in the patient and the pressures and flows generated by the ventilator are reproduced faithfully. A waveform of negative pressure, pmus, equivalent to the action of the respiratory muscles, is applied indirectly to the compliance unit of a conventional model lung. It is shown that, when the compliance and resistance of a subject have been measured, the waveform of pmus can be determined. This was undertaken in three volunteers breathing under various conditions, including connection to a ventilator operating in different modes. When these conditions were reproduced with the lung model replacing, but matched to, each subject, the original waveforms of flow and pressure at the mouth were reproduced.

The secondary pulmonary lobule: normal and abnormal CT appearances.

The secondary pulmonary lobule is a unit of lung supplied by three to five terminal bronchioles and contained by fibrous septa. High-resolution CT is able to show features of the secondary lobule, including interlobular septa, terminal bronchioles, and pulmonary arteries within a bronchiolovascular bundle. Because interstitial diseases have been shown to affect different components of the secondary lobule, high-resolution CT was used to compare the appearance of the normal secondary lobule with the abnormal secondary lobule in three patients with interstitial diseases primarily affecting lymphatic channels: lymphangitic carcinomatosis, sarcoidosis, and lymphangioleiomyomatosis. In lymphangitic carcinomatosis, the bronchiolovascular bundles and interlobular septa were thicker than those seen in a normal subject. In sarcoidosis, the interlobular septa and bronchiolovascular bundles were also thicker than normal. However, fibrosis caused distortion of the normal polygonal shape of the secondary lobule, not seen in either the normal subject or the patient with lymphangitic carcinomatosis. Lymphangioleiomyomatosis was characterized by multiple cysts within secondary lobules, often obliterating the normal polygonal appearance.

Structure of the avian respiratory tract

The avian lung is firmly attached to the thoracic wall and to the underlying horizontal septum. Its volume remains constant during respiration. Air sacs lie beneath the horizontal septum, the oblique septum separating them from the intestines; the abdominal air sac occupies the dorsal abdominal cavity. At the lung hilus the primary bronchus gives off four ventrobronchi, and posteriorly seven to ten dorsobronchi and the laterobronchi. Parabronchi, the functional unit of the avian lung for gas exchange, originate from the total internal surface of these secondary bronchi, connecting ventrobronchi to dorso- and laterobronchi. The three anterior air sacs are connected to the ventrobronchi. The posterior thoracic and the abdominal air sacs are connected to the large laterobronchus and to the end of the primary bronchus, respectively. The air sacs act as bellows ventilating the lung. The special shape of the primary bronchus, the origin of the secondary bronchi and the air sac connections determine the unidirectional ventilation of the parabronchi in this “paleopuimo” during both respiratory phases. This basic structure found in all birds is supplemented in more highly evolved species by a secondary parabronchial network, the “neopuimo”, connecting the primary bronchus and the posterior air sacs. It demonstrates a changing direction of air flow in accordance with the respiratory phase. The parabronchial structure and its vascular system are described.

Hypoxemia in pulmonary embolism, a clinical study.

The cause of hypoxemia was studied in 21 patients with no previous heart or lung disease shortly after an episode of acute pulmonary embolism. The diagnosis was based on pulmonary angiography demonstrating distinct vascular filling defects or "cutoffs." It was found that virtually all of the hypoxemia in patients with previously normal heart and lungs could be accounted for on the basis of shunt-like effect. The magnitude of the shunting did not correlate with the percent of the pulmonary vascular bed occluded nor with the mean pulmonary artery pressure. The shunts tended to gradually recede over about a month after embolism. Patients without pulmonary infarction were able to inspire 80-111% of their predicted inspiratory capacities, and this maneuver temporarily diminished the observed shunt. Patients with pulmonary infarcts were able to inhale only to 60-69% of predicted inspiratory capacity, and this did not reverse shunting. These data suggest that the cause of right-to-left shunting in patients with pulmonary emboli is predominantly atelectasis. When the elevation of mean pulmonary artery pressure was compared to cardiac index per unit of unoccluded lung, it fell within the range of pulmonary hypertension predicted from published data obtained in patients with exercise in all except one case. This observation suggests that pulmonary vasoconstriction following embolism is not important in humans, although these data are applicable only during the time interval in which our patients were studied and in patients receiving heparin.

Studies on multilayer membrane artificial lung.

Studies were carried out to devise a new multilayer membrane artifiilal lung. It was determined from the present studies on flow patterns and dye clearance that the basic design of the multilayer membrane artificial lung should have one-inlet and one -outlet and be elliptic in shap e. Many little projections were made on both surfaces of a distributing mat in order to support membranes and to give turbulences to the flowing blood. Distance between two membranes or the thickness of the blood layer was determined to be 0.8-0.9 mm. Fifty Hs silicon rubber was used as material for the distributing mats in order to prevent blood leakage from between the membranes. Silicon rubber membrane and Teflon membrane were investi gated for gas permeability by using a model of the elliptic artificial lung and a model of the Peirce-Galletti's a rtificial lung. Nineteen mongrel dogs were subjected to the studies. Phycon membrane or silicon rubber membrane, made in Japan, showed an excellent gas exchange capability and proved to be the best membrane now available. One unit of the artificial lung comprises two mats and two membranes, having an oxygenating surface area of 1540 cm2• This elliptic membrane artificial lung with a stack of t en oxygenating units has approxim ately 60 ml/ min of oxygen upta ke when Phycon membrane is used, and can be appli ed to total cardio­ pulmonary bypass for infants and small children.

Vasoconstriction and medial hypertrophy in pulmonary hypertension.

To determine whether thickening of the media of pulmonary muscular arteries in cases of pulmonary hypertension is the result of vasoconstriction or of hypertrophy or of both, a method for calculating the amount of arterial muscular tissue per unit of pulmonary tissue was devised. Comparison of the mean medial thickness, expressed as a percentage of the diameters of the arteries, with the amount of arterial muscular tissue per unit of lung, will give an impression as to whether vasoconstriction or hypertrophy prevails in a certain case. This method was applied to sections of pulmonary tissue from 10 normal controls and 17 patients with congenital cardiac disease with pulmonary hypertension. Medial hypertrophy was present in all cases of congenital heart disease studied as compared with controls, and was more pronounced in severe than in moderate pulmonary hypertension. In some cases also vasoconstriction appeared to play an important or even a dominant role in the thickening of the medial layer. In 2 cases of atrial septal defect with large pulmonary flow, hypertrophy was masked by dilatation of the vessels resulting in a relatively thin media.