Microextrusion Printing Cell-Laden Networks of Type I Collagen with Patterned Anisotropy and Geometry

Abstract

Type I collagen self-assembles into three-dimensional (3D) fibrous networks. These dynamic viscoelastic materials can be remodeled in response to mechanical and chemical cues to form anisotropic networks, the structure of which influences tissue development, homeostasis, and disease progression. Conventional approaches for fabricating anisotropic networks of type I collagen are often limited to unidirectional alignment over small areas. Here, we describe a new approach for engineering cell-laden anisotropic networks of type I collagen fibers using 3D microextrusion printing of a collagen-Matrigel ink. By adding molecular crowders, we demonstrate hierarchical control of 3D-printed collagen with the ability to spatially pattern collagen fiber anisotropy and geometry. Our data suggest that collagen anisotropy results from a combination of molecular crowding in the ink and shear and extensional flows present during 3D-printing. We demonstrate that human breast cancer cells cultured on 3D-printed collagen orient along the direction of collagen fiber alignment. We also demonstrate the ability to simultaneously bioprint epithelial cell clusters and control the alignment and geometry of collagen fibers surrounding cells in the bioink. The resulting cell-laden constructs consist of epithelial cell clusters fully embedded in aligned networks of collagen fibers. We foresee that cell-laden collagen-Matrigel constructs with spatially-patterned anisotropy and geometry will be broadly useful for the fields of developmental biology, tissue engineering, and regenerative medicine.