Magnetoactive, Kirigami-Inspired Hammocks to Probe Lung Epithelial Cell Function

Introduction

Mechanical forces provide critical biological signals to cells. Within the distal lung, tensile forces act across the basement membrane and epithelial cells atop. Stretching devices have supported studies of mechanical forces in distal lung epithelium to gain mechanistic insights into pulmonary diseases. However, the integration of curvature into devices applying mechanical forces onto lung epithelial cell monolayers has remained challenging. To address this, we developed a hammock-shaped platform that offers desired curvature and mechanical forces to lung epithelial monolayers.

Methods

We developed hammocks using polyethylene terephthalate (PET)-based membranes and magnetic-particle modified silicone elastomer films within a 48-well plate that mimic the alveolar curvature and tensile forces during breathing. These hammocks were engineered and characterized for mechanical and cell-adhesive properties to facilitate cell culture. Using human small airway epithelial cells (SAECs), we measured monolayer formation and mechanosensing using F-Actin staining and immunofluorescence for cytokeratin to visualize intermediate filaments.

Results

We demonstrate a multi-functional design that facilitates a range of curvatures along with the incorporation of magnetic elements for dynamic actuation to induce mechanical forces. Using this system, we then showed that SAECs remain viable, proliferate, and form an epithelial cell monolayer across the entire hammock. By further applying mechanical stimulation via magnetic actuation, we observed an increase in proliferation and strengthening of the cytoskeleton, suggesting an increase in mechanosensing.

Conclusion

This hammock strategy provides an easily accessible and tunable cell culture platform for mimicking distal lung mechanical forces in vitro. We anticipate the promise of this culture platform for mechanistic studies, multi-modal stimulation, and drug or small molecule testing, extendable to other cell types and organ systems.