Microengineered three-dimensional collagen landscapes with independently tunable fiber anisotropy and directionality

Abstract

Fibrillar collagens are structural proteins in the extracellular matrix (ECM), and cellular processes, including differentiation, proliferation, and migration, have been linked to the orientation (directionality) and alignment (anisotropy) of collagen fibers. Given the importance of cell-substrate interactions in driving biological functions, several microfluidic approaches have demonstrated three-dimensional (3D) collagen gels with defined fiber properties that enable quantitative correlations between structural cues and observed cell responses. Although existing methods provide excellent definition over collagen fiber anisotropy, independent control over both anisotropy and directionality (that we collectively refer to as the collagen landscape) has not been demonstrated. Therefore, to advance collagen microengineering capabilities, we present a user-friendly approach that uses controlled fluid flows within a non-uniform microfluidic channel network to create well-defined collagen landscapes. We demonstrate capabilities including i) control over fiber anisotropy, ii) spatial gradients in fiber anisotropy, iii) defined fiber directionality, and iv) multi-material interfaces. We then show that cells respond to the microengineered topographic cues by aligning along the anisotropy domains and following fiber directionality. Finally, this platforms modular capability is demonstrated by integrating an ultrathin porous parylene (UPP) membrane on the microengineered collagen as a mask to control cell-substrate interactions.