Microengineering Aligned Collagen Substrates In Microfluidic Systems

Cells in vivo are surrounded by a fibrous matrix of proteins and macromolecules called the extracellular matrix (ECM), of which type I collagen is the major constituent. During tissue development or cell-matrix interactions, collagen fibers organize into aligned domains with defined degrees of alignment and directionality. Aligned fibers guide stem cell differentiation and influence cell-cell communication and cell motility. In the tumor microenvironment, aligned fibers guide tumor cell invasion and have been linked to poor patient outcomes. Since fiber alignment instructs cell behavior in vivo, there is a need for in vitro models to replicate fiber alignment and thus provide a relevant microenvironment for cells. Microfluidic systems have been established as advanced cell culture platforms to provide precise control over soluble factor concentration, cell patterning, and fluid flow. However, controlling the fiber alignment of a 3D material within them has remained a challenge. This work addresses existing technological challenges to integrate 3D collagen matrices with aligned fibers into microfluidic platforms. To do so, this work i) Demonstrates for the first time that extensional flows can align 3D collagen matrices (250 µm thick) in a microchannel, ii) Develops modular microfluidic platforms with capabilities to directly access and perfuse 3D collagen, and iii) Develops biofabrication capabilities to create interfaces between different ECM materials in 3D, and create tissue barriers using ultrathin nanomembranes. It is anticipated that the novel ECM microengineering capabilities and approach to integrating the engineered matrices into microfluidic devices will provide a path to develop tissue-specific in vitro models with engineered matrices