4D Time-lapse imaging of cell dynamics in human alveolar tissue by label-free higher harmonic generation microscopy

BACKGROUND: Current methods to study patient-specific disease processes rely on a variety of ex vivo techniques, like static histological analysis or tissue cultures with static endpoints, that provide limited insight into how the tissue microenvironment behaves in real time. Yet, dynamic features, such as immune cell infiltration and extracellular matrix remodeling, are crucial predictors of therapy response, be it in cancer or fibrotic diseases. At present, no label-free and clinically viable assay exists that can capture these behaviors in live human tissue. METHODS: We propose an innovative platform that provides metrics on cell density, cell dynamics and microstructure of the extracellular matrix for the characterization of treatment response. The platform integrates fully label-free, time-lapse 3D higher harmonic generation microscopy to visualize both cells and the extracellular matrix, and a stage-top incubator in which tissue slices are cultured during time-lapse measurements. RESULTS: Here, we demonstrate the viability of the tissue slices during imaging and the ability to resolve endogenous immune cell and seeded monocyte dynamics, in the context of healthy alveolar structures. Time-lapse dynamics were recorded in 3D for up to 59 hours during a total culture period of 90 hours, and the migration of endogenous smaller cells and seeded monocytes was tracked and analyzed. CONCLUSIONS: This platform is relatively simple to operate and has potential for studies on drug development and patient-specific treatment response prediction in the context of human lung disease.