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

Abstract

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.

Evolution of Bioengineered Lung Models: Recent Advances and Challenges in Tissue Mimicry for Studying the Role of Mechanical Forces in Cell Biology

“…The modified version of this model enables online monitoring of transepithelial electrical resistance (TEER) in real‐time using a microimpedance tomography system (at a distance of 1 mm from the electrodes) . In addition, the microfluidic device used in this study can be equipped with a passive medium exchange unit to provide long‐term culture conditions under ALI …”

Host and Pathogen Communication in the Respiratory Tract: Mechanisms and Models of a Complex Signaling Microenvironment

“…In fact, human primary pulmonary alveolar cells collected from patients who underwent partial lung resection were utilized in this model, illustrating its applicability for valuable cell populations (223). This model has also been used for applications such as wound healing (224) and has been modified to include microelectronics for impedance measurements (225). Similar to the Huh et al (188) model, this model can be used for study of cross-talk such as direct or soluble factor signaling, as pathogens can be directly introduced on the apical side or conditioned media can be introduced to the bottom compartment.…”

“…Innovative organotypic and tissue engineered models have incorporated key biological functions (219,220), extracellular matrix (ECM) and structural components (188,221,222), mechanical stimuli (188,(221)(222)(223)(224)(225), and placement of pathogens with respect to lung tissue components to mimic in vivo interactions. These in vitro models allow researchers to hone in on specific aspects of the lung physiology and manipulate conditions to better understand the underlying signaling mechanisms governing the pathology of infection.…”

Drug Toxicity Evaluation Based on Organ-on-a-chip Technology: A Review

“…The results proved that cyclic mechanical stretching had a significant effect on the wound healing process. The main results of these studies will help us to understand the complex pathogenesis of idiopathic pulmonary fibrosis (IPF) [129].…”