Progressive lung fibrosis is associated with poorly understood aging-related endothelial cell dysfunction. To gain insight into endothelial cell alterations in lung fibrosis we performed single cell RNA-sequencing of bleomycin-injured lungs from young and aged mice. Analysis reveals activated cell states enriched for hypoxia, glycolysis and YAP/TAZ activity in ACKR1+ venous and TrkB+ capillary endothelial cells. Endothelial cell activation is prevalent in lungs of aged mice and can also be detected in human fibrotic lungs. Longitudinal single cell RNA-sequencing combined with lineage tracing demonstrate that endothelial activation resolves in young mouse lungs but persists in aged ones, indicating a failure of the aged vasculature to return to quiescence. Genes associated with activated lung endothelial cells states in vivo can be induced in vitro by activating YAP/TAZ. YAP/TAZ also cooperate with BDNF, a TrkB ligand that is reduced in fibrotic lungs, to promote capillary morphogenesis. These findings offer insights into aging-related lung endothelial cell dysfunction that may contribute to defective lung injury repair and persistent fibrosis.

The lung has a vital function in gas exchange between the blood and the external atmosphere. It also has a critical role in the immune defense against external pathogens and environmental factors. While the lung is classified as a relatively quiescent organ with little homeostatic turnover, it shows robust regenerative capacity in response to injury, mediated by the resident stem/progenitor cells. During regeneration, regionally distinct epithelial cell populations with specific functions are generated from several different types of stem/progenitor cells localized within four histologically distinguished regions: trachea, bronchi, bronchioles, and alveoli. WNT signaling is one of the key signaling pathways involved in regulating many types of stem/progenitor cells in various organs. In addition to its developmental role in the embryonic and fetal lung, WNT signaling is critical for lung homeostasis and regeneration. In this minireview, we summarize and discuss recent advances in the understanding of the role of WNT signaling in lung regeneration with an emphasis on stem/progenitor cells.

Environmental contamination by trinitrotoluene is of global concern due to its widespread use in military ordnance and commercial explosives. Despite known long-term persistence in groundwater and soil, the toxicological profile of trinitrotoluene and other explosive wastes have not been systematically measured using in vivo biological assays. Zebrafish embryos are ideal model vertebrates for high-throughput toxicity screening and live in vivo imaging due to their small size and transparency during embryogenesis. Here, we used Single Plane Illumination Microscopy (SPIM)/light sheet microscopy to assess the developmental toxicity of explosive-contaminated water in zebrafish embryos and report 2,4,6-trinitrotoluene-associated developmental abnormalities, including defects in heart formation and circulation, in 3D. Levels of apoptotic cell death were higher in the actively developing tissues of trinitrotoluene-treated embryos than controls. Live 3D imaging of heart tube development at cellular resolution by light-sheet microscopy revealed trinitrotoluene-associated cardiac toxicity, including hypoplastic heart chamber formation and cardiac looping defects, while the real time PCR (polymerase chain reaction) quantitatively measured the molecular changes in the heart and blood development supporting the developmental defects at the molecular level. Identification of cellular toxicity in zebrafish using the state-of-the-art 3D imaging system could form the basis of a sensitive biosensor for environmental contaminants and be further valued by combining it with molecular analysis.

Bioactive films with a nanoplate structure were prepared on the surface of a biodegradable AZ31B magnesium (Mg) alloy via anodization in simulated body fluid (SBF) as an electrolyte to control Mg biodegradability and improve surface bioactivity. The effect of the electrolyte temperature and pH values on the formation of the biomimetic film were studied. The electrolyte was set at three different temperatures of 37, 50, and 80 °C, with pH values ranging from 7.4 to 8 for the lower electrolyte temperature and 11.5–12 for the two higher levels of temperature. The apatite films on the different samples were characterized using X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM), EDS element mapping, X-ray photon spectroscopy (XPS), and FTIR spectroscopy. The water contact angles of the different surfaces were evaluated, moreover, the corrosion behaviors of the different samples were studied using electrochemical potentiodynamic DC, electrochemical impedance spectroscopy (EIS), and immersion tests. The human fetal-osteoblast cell line hFOB 1.19 was used in a cell culture test, and the biological response and cell function were evaluated in vitro using DNA and PCR. The decomposition of the apatite film was affected by the anodization electrolyte temperature, resulting in an amorphous structure. It is observed that the apatite structure has nanoplates at electrolyte temperature (37 to 50) °C and these have a tendency to disappear at 80 °C.