Interpreting tissue stiffening with lung tumorigenesis by imaging architectural resembling of extracellular matrix components

Lung cancer leads to a series of physiological abnormalities. The remodeling of extracellular matrix (especially elastin and collagen fibers) has been drawing increasing attention as it is suggested to be a hallmark of tumorigenesis. However, the interaction between these crucial matrix components, together with their relationship to mechanical changes, remains poorly understood. Here, we develop a quantitative multiphoton microscopy system to elucidate the relationship between tissue stiffening and elastin-collagen interplay in lung cancer. Based on label-free images of both fibers, we establish a metric termed resemblance metric (RM) to characterize their interaction by quantifying the similarity of their morpho-structural distributions. Specifically, RM is found to increase with lung tumorigenesis, and exhibits superior sensitivity in identifying human lung cancer through ex vivo quantitative imaging. Nanoindentation results suggest a strong correlation between tissue stiffness and inter-channel interaction, notably greater than that between stiffness and any individual morpho-structural feature of either fiber type. Finally, the translational potential of RM-based imaging is demonstrated through tumor boundary identification via in vivo imaging within a mouse model harboring human lung cancer. Unique remodeling of elastin and collagen fibers in extracellular matrix along lung tumorigenesis is resolved with label-free multiphoton microscopy and a quantitative measure termed resemblance metric.