Microfabrication of extracellular matrix structures using multipohoton-excited photochemistry: Application to modeling ovarian tissue in vitro

The extracellular matrix plays a crucial role in tissue development, differentiation and homeostasis by providing the necessary biophysical and biochemical cues for the cells. In tumors, the composition and the structure of the microenvironment is thought to be manipulated by the cancers cells to support proliferative growth and enhanced migration as means of facilitated metastasis. Current in vitro tools to address these mechanistic events in tumor progression are lacking in part due to the difficulty in recapitulating the complexity of the composition and nanoarchitecture of the tumor microenvironment. In this thesis, we explore the feasibility of multiphoton-excited photochemistry as a fabrication tool for generating in vitro scaffolds that are highly repeatable, biologically relevant and relatively affordable in a research setting. The power of this technique lays in the capabilities of crosslinking whole extracellular matrix proteins in three dimensions (3D) to recreate key topographical features of the tissue with sub-micron resolution and high fidelity. The technological developments we present here enable direct translation of matrix topographies by using the high resolution image data of the tissue samples as a fabrication template.;To this effect, we have applied the fabrication technique to generate gradients of crosslinked proteins as means of studying the role of haptotaxis in ovarian and breast cancers. Our findings show that cancer cells modulate their migration velocity and persistence in response to the changes in the composition of the extracellular matrix. In addition, we have examined structural features of the stroma in relation to cancer migration dynamics. We find that by recreating highly aligned nanoarchitectural features prevalent in cancer stroma, we see permissive and enhanced cell migration with cell morphologies similar to in vivo.;We believe multiphoton fabrication to be an enabling tool in the next generation of tissue scaffolding. Having the means to carefully recreate complex topographies can ultimately enhance our knowledge of cancer migration in 3D environments as well as provide valued insights in developing novel therapies aim at treating this disease.