Compressive Remodeling Alters Fluid Transport Properties of Collagen Networks - Implications for Tumor Growth

Biomechanical alterations to the tumor microenvironment include accumulation of solid stresses, extracellular matrix (ECM) stiffening and increased fluid pressure in both interstitial and peri-tumoral spaces. The relationship between interstitial fluid pressurization and ECM remodeling in vascularized tumors is well characterized, while earlier biomechanical changes occurring during avascular tumor growth within the peri-tumoral ECM remain poorly understood. Type I collagen, the primary fibrous ECM constituent, bears load in tension while it buckles under compression. We hypothesized that tumor-generated compressive forces cause collagen remodeling via densification which in turn creates a barrier to convective fluid transport and may play a role in tumor progression and malignancy. To better understand this process, we characterized the structure-function relationship of collagen networks under compression both experimentally and computationally. Here we show that growth of epithelial cancers induces compressive remodeling of the ECM, documented in the literature as a TACS-2 phenotype, which represents a localized densification and tangential alignment of peritumoral collagen. Such compressive remodeling is caused by the unique features of collagen network mechanics, such as fiber buckling and cross-link rupture, and reduces the overall hydraulic permeability of the matrix.