Second harmonic generation imaging of collagen changes in idiopathic pulmonary fibrosis

We use SHG microscopy to study collagen alterations in idiopathic pulmonary fibrosis (IPF) in human tissues and in vitro models. Texture analysis successfully classified the fiber morphology in normal and IPF tissues at near 100% accuracy. SHG polarization measurement indicated reduced chirality in the collagen triple helix in IPF in both tissues and spheroid models. Using SHG directional measurements (F/B), we found the collagen fibril and macromolecular structures are altered in IPF, consistent with decreased organization. We are developing a rigorous phasematching approach to determine the collagen fibril size, packing, and polarity based on these measurements.