Glutamine maintains the stability of alveolar structure and function after lung transplantation by inhibiting autophagy.

Excessive autophagy may lead to degradation and damage of alveolar epithelial cells after lung transplantation, eventually leading to alveolar epithelial cell loss, affecting the structural integrity and function of alveoli. Glutamine (Gln), a nutritional supplement, regulates autophagy through multiple signaling pathways. In this study, we explored the protective role of Gln on alveolar epithelial cells by inhibiting autophagy. In vivo, a rat orthotopic lung transplant model was carried out to evaluate the therapeutic effect of glutamine. Ischemia/reperfusion (I/R) induced alveolar collapse, edema, epithelial cell apoptosis, and inflammation, which led to a reduction of alveolar physiological function, such as an increase in peak airway pressure, and a decrease in lung compliance and oxygenation index. In comparison, Gln preserved alveolar structure and function by reducing alveolar apoptosis, inflammation, and edema. In vitro, a hypoxia/reoxygenation (H/R) cell model was performed to simulate IR injury on mouse lung epithelial (MLE) cells and human lung bronchus epithelial (Beas-2B) cells. H/R impaired the proliferation of epithelial cells and triggered cell apoptosis. In contrast, Gln normalized cell proliferation and suppressed I/R-induced cell apoptosis. The activation of mTOR and the downregulation of autophagy-related proteins (LC3, Atg5, Beclin1) were observed in Gln-treated lung tissues and alveolar epithelial cells. Both in vivo and in vitro, rapamycin, a classical mTOR inhibitor, reversed the beneficial effects of Gln on alveolar structure and function. Taken together, Glnpreserved alveolar structure and function after lung transplantation by inhibiting autophagy.

Dynamic evaluation of acute lung injury using hyperpolarized 129 Xe magnetic resonance.

Prognosticating acute lung injury (ALI) is challenging, in part because of a lack of sensitive biomarkers. Hyperpolarized gas magnetic resonance (MR) has unique advantages in pulmonary function measurement and can provide promising biomarkers for the assessment of lung injuries. Herein, we employ hyperpolarized 129 Xe MRI and generate a number of imaging biomarkers to detect the pulmonary physiological and morphological changes during the progression of ALI in an animal model. We find the measured ratio of 129 Xe in red blood cells to interstitial tissue/plasma (RBC/TP) is significantly lower in the ALI group on the second (0.32 ± 0.03, p = 0.004), seventh (0.23 ± 0.03, p < 0.001), and 14th (0.29 ± 0.04, p = 0.001) day after lipopolysaccharide treatment compared with that in the control group (0.41 ± 0.04). In addition, significant differences are also observed for RBC/TP measurements between the second and seventh day (p = 0.001) and between the seventh and 14th day (p = 0.018) in the ALI group after treatment. Besides RBC/TP, significant differences are also observed in the measured exchange time constant (T) on the second (p = 0.038) and seventh day (p = 0.009) and in the measured apparent diffusion coefficient (ADC) and alveolar surface-to-volume ratio (SVR) on the 14th day (ADC: p = 0.009 and SVR: p = 0.019) after treatment in the ALI group compared with that in the control group. These findings indicate that the parameters measured with 129 Xe MR can detect the dynamic changes in pulmonary structure and function in an ALI animal model.

Lung tissue phantom mimicking pulmonary optical properties, relative humidity, and temperature: a tool to analyze the changes in oxygen gas absorption for different inflated volumes.

SIGNIFICANCE: Gas in scattering media absorption spectroscopy (GASMAS) enables noninvasive gas sensing in the body. It is developing as a tool for diagnosis and monitoring of respiratory conditions in neonates. Phantom models with relevant features to the clinical translation of GASMAS technology are necessary to understand technical challenges and potential applications of this technique. State-of-the-art phantoms designed for this purpose have focused on the optical properties and anthropomorphic geometry of the thorax, contributing to the source-detector placement, design, and optimization. Lung phantom mimicking the alveolar anatomy has not been included in the existent models due to the inherent complexity of the tissue. We present a simplified model that recreates inflated alveoli embedded in lung phantom. AIM: The goal of this study was to build a lung model with air-filled structures mimicking inflated alveoli surrounded by optical phantom with accurate optical properties (µa = 0.50 cm - 1 and µs'=5.4 cm-1) and physiological parameters [37°C and 100% relative humidity (RH)], and to control the air volume within the phantom to demonstrate the feasibility of GASMAS in sensing changes in pulmonary air volume. APPROACH: The lung model was built using a capillary structure with analogous size to alveolar units. Part of the capillaries were filled with liquid lung optical phantom to recreate scattering and absorption, whereas empty capillaries mimicked air filled alveoli. The capillary array was placed inside a custom-made chamber that maintained pulmonary temperature and RH. The geometry of the chamber permitted the placement of the laser head and detector of a GASMAS bench top system (MicroLab Dual O2 / H2O), to test the changes in volume of the lung model in transmittance geometry. RESULTS: The lung tissue model with air volume range from 6.89 × 10 - 7 m3 to 1.80 × 10 - 3 m3 was built. Two measurement sets, with 10 different capillary configurations each, were arranged to increase or decrease progressively (in steps of 3.93 × 10 - 8 m3) the air volume in the lung model. The respective GASMAS data acquisition was performed for both data sets. The maximum absorption signal was obtained for configurations with the highest number of air-filled capillaries and decreased progressively when the air spaces were replaced by capillaries filled with liquid optical phantom. Further studies are necessary to define the minimum and maximum volume of air that can be measured with GASMAS-based devices for different source-detector geometries. CONCLUSIONS: The optical properties and the structure of tissue from the respiratory zone have been modeled using a simplified capillary array immersed in a controlled environment chamber at pulmonary temperature and RH. The feasibility of measuring volume changes with GASMAS technique has been proven, stating a new possible application of GASMAS technology in respiratory treatment and diagnostics.

Differentiation of Human Induced Pluripotent Stem Cells to Mammary-like Organoids.

Human induced pluripotent stem cells (iPSCs) can give rise to multiple cell types and hold great promise in regenerative medicine and disease-modeling applications. We have developed a reliable two-step protocol to generate human mammary-like organoids from iPSCs. Non-neural ectoderm-cell-containing spheres, referred to as mEBs, were first differentiated and enriched from iPSCs using MammoCult medium. Gene expression profile analysis suggested that mammary gland function-associated signaling pathways were hallmarks of 10-day differentiated mEBs. We then generated mammary-like organoids from 10-day mEBs using 3D floating mixed gel culture and a three-stage differentiation procedure. These organoids expressed common breast tissue, luminal, and basal markers, including estrogen receptor, and could be induced to produce milk protein. These results demonstrate that human iPSCs can be directed in vitro toward mammary lineage differentiation. Our findings provide an iPSC-based model for studying regulation of normal mammary cell fate and function as well as breast disease development.

Pulmonary ventilation and micro-structural findings in congenital diaphragmatic hernia.

BACKGROUND: With increasing survival of patients with more severe forms of congenital diaphragmatic hernia (CDH) and risk of long-term respiratory morbidity, studies on lung morphology are needed. We used hyperpolarised (3) He MRI and anatomical (1) H MRI in a cohort of young adult CDH patients to image regional lung ventilation and microstructure, focusing on morphological and micro-structural (alveolar) abnormalities. METHODS: Nine patients with left-sided CDH, born 1975-1993, were studied. Regional ventilation was imaged with hyperpolarised (3) He MRI, and the (3) He apparent diffusion coefficient (ADC) was computed separately for the ipsilateral and contralateral lungs. (1) H MRI was used to image lung anatomy, total lung volume and motion during free-breathing. RESULTS: (3) He MRI showed ventilation abnormalities in six patients, ranging from a single ipsilateral ventilation defect (3 patients) to multiple ventilation defects in both lungs (one patient treated with extra corporeal membrane oxygenation). In eight patients, (3) He ADC values for the ipsilateral lung were significantly higher than those for the contralateral lung. CONCLUSIONS: Functional and micro-structural changes persist into adulthood in most CDH patients. Ipsilateral elevated (3) He ADC values are consistent with enlargement of mean dimensions of the confining lung micro-structure at the alveolar level.