Impaired Wound Healing of Alveolar Lung Epithelial Cells in a Breathing Lung-On-A-Chip.

The lung alveolar region experiences remodeling during several acute and chronic lung diseases, as for instance idiopathic pulmonary fibrosis (IPF), a fatal disease, whose onset is correlated with repetitive microinjuries to the lung alveolar epithelium and abnormal alveolar wound repair. Although a high degree of mechanical stress (>20% linear strain) is thought to potentially induce IPF, the effect of lower, physiological levels of strain (5-12% linear strain) on IPF pathophysiology remains unknown. In this study, we examined the influence of mechanical strain on alveolar epithelial wound healing. For this purpose, we adopted the "organ-on-a-chip" approach, which provides the possibility of reproducing unique aspects of the in vivo cellular microenvironment, in particular its dynamic nature. Our results provide the first demonstration that a wound healing assay can be performed on a breathing lung-on-a-chip equipped with an ultra-thin elastic membrane. We cultured lung alveolar epithelial cells to confluence, the cells were starved for 24 h, and then wounded by scratching with a standard micropipette tip. Wound healing was assessed after 24 h under different concentrations of recombinant human hepatic growth factor (rhHGF) and the application of cyclic mechanical stretch. Physiological cyclic mechanical stretch (10% linear strain, 0.2 Hz) significantly impaired the alveolar epithelial wound healing process relative to culture in static conditions. This impairment could be partially ameliorated by administration of rhHGF. This proof-of-concept study provides a way to study of more complex interactions, such as a co-culture with fibroblasts, endothelial cells, or immune cells, as well as the study of wound healing at an air-liquid interface.

A lung-on-a-chip array with an integrated bio-inspired respiration mechanism.

We report a lung-on-a-chip array that mimics the pulmonary parenchymal environment, including the thin alveolar barrier and the three-dimensional cyclic strain induced by breathing movements. The micro-diaphragm used to stretch the alveolar barrier is inspired by the in vivo diaphragm, the main muscle responsible for inspiration. The design of this device aims not only at best reproducing the in vivo conditions found in the lung parenchyma but also at making the device robust and its handling easy. An innovative concept, based on the reversible bonding of the device, is presented that enables accurate control of the concentration of cells cultured on the membrane by easily accessing both sides of the membranes. The functionality of the alveolar barrier could be restored by co-culturing epithelial and endothelial cells that form tight monolayers on each side of a thin, porous and stretchable membrane. We showed that cyclic stretch significantly affects the permeability properties of epithelial cell layers. Furthermore, we also demonstrated that the strain influences the metabolic activity and the cytokine secretion of primary human pulmonary alveolar epithelial cells obtained from patients. These results demonstrate the potential of this device and confirm the importance of the mechanical strain induced by breathing in pulmonary research.

Intravenous iron alone resolves anemia in patients with functional iron deficiency and lymphoid malignancies undergoing chemotherapy.

This randomized trial evaluated ferric carboxymaltose without erythropoiesis-stimulating agents (ESA) for correction of anemia in cancer patients with functional iron deficiency. Patients on treatment for indolent lymphoid malignancies, who had anemia [hemoglobin (Hb) 8.5-10.5 g/dL] and functional iron deficiency [transferrin saturation (TSAT) ≤ 20%, ferritin >30 ng/mL (women) or >40 ng/mL (men)], were randomized to ferric carboxymaltose (1,000 mg iron) or control. Primary end point was the mean change in Hb from baseline to weeks 4, 6 and 8 without transfusions or ESA. Difficulties with patient recruitment led to premature termination of the study. Seventeen patients (8 ferric carboxymaltose and 9 control) were included in the analysis. In the ferric carboxymaltose arm, mean Hb increase was significantly higher versus control at week 8 (p = 0.021). All ferric carboxymaltose-treated patients achieved an Hb increase >1 g/dL (control 6/9; p = 0.087), and mean TSAT was >20% from week 2 onwards. No treatment-related adverse events were reported. In conclusion, ferric carboxymaltose without ESA effectively increased Hb and iron status in this small patient population.

Ferric carboxymaltose prevents recurrence of anemia in patients with inflammatory bowel disease.

BACKGROUND & AIMS: Iron-deficiency anemia is the most common systemic complication of inflammatory bowel diseases (IBD). Iron-deficiency anemia recurs frequently and rapidly after iron-replacement therapy in patients with IBD. We performed a randomized, placebo-controlled trial to determine if administration of ferric carboxymaltose (FCM) prevents anemia in patients with IBD and low levels of serum ferritin. METHODS: We performed a single-blind, multicenter study of nonanemic patients who had completed the FERGIcor study. Serum levels of ferritin were assessed every second month, and patients were given FCM (total iron dose, 1181 ± 662 mg; n = 105) or placebo (n = 99) when levels decreased to less than 100 µg/L. The primary end point was time to recurrence of anemia within 8 months. Secondary end points included changes of quality of life, disease activity, results from laboratory tests, and adverse events. RESULTS: Anemia recurred in 26.7% of subjects given FCM and in 39.4% given placebo. The time to anemia recurrence was longer in the FCM group (hazard ratio, 0.62; 95% confidence interval, 0.38-1.00; P = .049). Markers of body levels of iron increased or remained at normal levels in subjects given FCM (ferritin increased by 30.3 µg/L, transferrin saturation increased by 0.6%) but decreased in the group given placebo (ferritin decreased by 36.1 µg/L, transferrin saturation decreased by 4.0%). Changes in quality of life and disease activity were comparable between groups. Adverse events were reported in 59.0% of the FCM group and 50.5% of the placebo group, and serious adverse events were reported in 6.7% and 8.1%, respectively. CONCLUSIONS: FCM prevents recurrence of anemia in patients with IBD, compared with placebo. Nevertheless, the high rate of anemia recurrence warrants optimization of the frequency and requirements for FCM treatment.

Microfluidic wound-healing assay to assess the regenerative effect of HGF on wounded alveolar epithelium.

We present a microfluidic epithelial wound-healing assay that allows characterization of the effect of hepatocyte growth factor (HGF) on the regeneration of alveolar epithelium using a flow-focusing technique to create a regular wound in the epithelial monolayer. The phenotype of the epithelial cell was characterized using immunostaining for tight junction (TJ) proteins and transmission electron micrographs (TEMs) of cells cultured in the microfluidic system, a technique that is reported here for the first time. We demonstrate that alveolar epithelial cells cultured in a microfluidic environment preserve their phenotype before and after wounding. In addition, we report a wound-healing benefit induced by addition of HGF to the cell culture medium (19.2 vs. 13.5 µm h(-1) healing rate).