title: Mechanical properties of the tumor stromal microenvironment probedin vitroandex vivobyin situ-calibrated optical trap-based active microrheology.
abstract: One of the hallmarks of the malignant transformation of epithelial tissue is the modulation of stromal components of the microenvironment. In particular, aberrant extracellular matrix (ECM) remodeling and stiffening enhances tumor growth and survival and promotes metastasis. Type I collagen is one of the major ECM components. It serves as a scaffold protein in the stroma contributing to the tissue's mechanical properties, imparting tensile strength and rigidity to tissues such as those of the skin, tendons, and lungs. Here we investigate the effects of intrinsic spatial heterogeneities due to fibrillar architecture, pore size and ligand density on the microscale and bulk mechanical properties of the ECM. Type I collagen hydrogels with topologies tuned by polymerization temperature and concentration to mimic physico-chemical properties of a normal tissue and tumor microenvironment were measured byin situ-calibratedActiveMicrorheology byOpticalTrapping revealing significantly different microscale complex shear moduli at Hz-kHz frequencies and two orders of magnitude of strain amplitude that we compared to data from bulk rheology measurements. Access to higher frequencies enabled observation of transitions from elastic to viscous behavior that occur at ~200Hz to 2750Hz, which largely was dependent on tissue architecture well outside the dynamic range of instrument acquisition possible with SAOS bulk rheology. We determined that mouse melanoma tumors and human breast tumors displayed complex moduli ~5-1000 Pa, increasing with frequency and displaying a nonlinear stress-strain response. Thus, we show the feasibility of a mechanical biopsy in efforts to provide a diagnostic tool to aid in the design of therapeutics complementary to those based on standard histopathology.
authors.affiliation: Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute (NIH), Bethesda, MD 20892, USA.
authors.forename: Jack R
authors.initials: JR
authors.lastname: Staunton
authors.affiliation: Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute (NIH), Bethesda, MD 20892, USA.
authors.forename: Wilfred
authors.initials: W
authors.lastname: Vieira
authors.affiliation: Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute (NIH), Bethesda, MD 20892, USA.
authors.forename: King Leung
authors.initials: KL
authors.lastname: Fung
authors.affiliation: Laboratory of Genitourinary Cancer Pathogenesis, Center for Cancer Research, National Cancer Institute (NIH), Bethesda, MD 20892, USA.
authors.forename: Ross
authors.initials: R
authors.lastname: Lake
authors.affiliation: Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute (NIH), Bethesda, MD 20892, USA.
authors.forename: Alexus
authors.initials: A
authors.lastname: Devine
authors.affiliation: Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute (NIH), Bethesda, MD 20892, USA.
authors.forename: Kandice
authors.initials: K
authors.lastname: Tanner
keywords: biomaterials; biopsy; hydrogels; microrheology; optical traps; tissue mechanics