  An organoid is a three-dimensional (3D) in vitro cell culture emulating human
organs. We applied 3D dynamic optical coherence tomography (DOCT) to visualize
the intratissue and intracellular activities of human induced pluripotent stem
cells (hiPSCs)-derived alveolar organoids in normal and fibrosis models. 3D
DOCT data were acquired with an 840-nm spectral domain optical coherence
tomography with axial and lateral resolutions of 3.8 {\mu}m (in tissue) and 4.9
{\mu}m, respectively. The DOCT images were obtained by the
logarithmic-intensity-variance (LIV) algorithm, which is sensitive to the
signal fluctuation magnitude. The LIV images revealed cystic structures
surrounded by high-LIV borders and mesh-like structures with low LIV. The
former may be alveoli with a highly dynamics epithelium, while the latter may
be fibroblasts. The LIV images also demonstrated the abnormal repair of the
alveolar epithelium.
