Collagen‐I/silk‐fibroin biocomposite exhibits microscalar confinement of cells and induces anisotropic morphology and migration of embedded fibroblasts

Abstract

Abstract Microstructural anisotropy of tumor‐associated matrix correlates with invasion of cancer cells into the surrounding matrix during metastasis. Here, we report the fabrication and characterization of a three‐dimensional (3D) silk‐fibroin/collagen‐I bio‐composite based cell‐culture model that exhibits microstructural and biochemical anisotropy. Using RGD‐deficient silk‐fibroin fibers to confine collagen‐I gelation, we develop a silk‐fibroin/collagen‐I (SFC) bio‐composite in a one‐step process allowing control over the microstructural and biochemical anisotropy and the pore‐size. Two forms of the SFC bio‐composite are reported: a sandwich ( S fc ) configuration amenable to live‐cell microscopy and an unsupported membrane ( M fc ) for use as a scaffold. Both microscalar and macroscalar mechanical properties of the SFC bio‐composite are characterized using atomic force microscope (AFM)‐based indentation and tensile‐testing. We find that the modulus of stiffness of both S fc and M fc can be controlled and falls in the physiological range of 5–20 kPa. Furthermore, the modulus of stiffness of M fc exhibits a ~200% increase in axial direction of microstructure, as compared to lateral direction. This implies a highly anisotropic mechanical stiffness of the microenvironment. Live‐cell morphology and migration studies show that both the morphology and the migration of NIH‐3 T3 fibroblasts is anisotropic and correlates with microstructural anisotropy. Our results show that SFC bio‐composite permits proliferation of cells in both S fc and M fc configuration, promotes cell‐migration along the major axis of anisotropy and together with morphological and migration data, suggest a potential application of both the composite configurations as a biomimetic scaffold for tissue engineering applications.

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