To elucidate the chemical and environmental conditions that promote invasion of cancer cells, an assay is needed in which the chemical landscape of a tumor-like environment can be experimentally manipulated and probed. The three-dimensional paper-based invasion assays described here simulate poorly vascularized tissue and allow the invasion of cancerous cells to be visualized and quantified. These cultures are easy to assemble and allow multiple invasion assays to be performed in parallel. By using different materials to control gradients formed across the culture, the chemotactic potential of small molecules can be evaluated in a more representative tissue microenvironment. © 2017 by John Wiley & Sons, Inc.

The implications are directed at novel therapeutic and diagnostic clinical applications of amylase such as the novel therapeutic drug classes capable of targeted delivery and "smart release" in areas of clinical need. Future directions of research in areas of high clinical benefit are reported.

Cellular invasion is the gateway to metastasis, which is the leading cause of cancer-related deaths. Invasion is driven by a number of chemical and mechanical stresses that arise in the tumor microenvironment. In vitro assays are needed for the systematic study of cancer progress. To be truly predictive, these assays must generate tissue-like environments that can be experimentally controlled and manipulated. While two-dimensional (2D) monolayer cultures are easily assembled and evaluated, they lack the extracellular components needed to assess invasion. Three-dimensional (3D) cultures are better suited for invasion studies because they generate cellular phenotypes that are more representative of those found in vivo. This feature article provides an overview of four invasion platforms. We focus on paper-based cultures, an emerging 3D culture platform capable of generating tissue-like structures and quantifying cellular invasion. Paper-based cultures are as easily assembled and analyzed as monolayers, but provide an experimentally powerful platform capable of supporting: co-cultures and representative extracellular environments; experimentally controlled gradients; readouts capable of quantifying, discerning, and separating cells based on their invasiveness. With a series of examples we highlight the potential of paper-based cultures, and discuss how they stack up against other invasion platforms.