Cellular Invasion Assay for the Real-Time Tracking of Individual Cells in Spheroid or Tumor-like Mimics.

Cellular invasion is the gateway to metastasis, with cells moving from a primary tumor into neighboring regions of healthy tissue. Invasion assays provide a tractable experimental platform to quantitatively assess cellular movement in the presence of potential chemokines or inhibitors. Many such assays involve cellular movement from high cell densities to cell-free regions.

Generating linear oxygen gradients across 3D cell cultures with block-layered oxygen controlled chips (BLOCCs).

Oxygen is a transcriptional regulator responsible for tissue homeostasis and maintenance. Studies relating cellular phenotype with oxygen tension often use hypoxia chambers, which expose cells to a single, static oxygen tension. Despite their ease of use, these chambers are unable to replicate the oxygen gradients found in healthy and diseased tissues.

Paper-based Transwell assays: an inexpensive alternative to study cellular invasion.

Cellular movement is essential in the formation and maintenance of healthy tissues as well as in disease progression such as tumor metastasis. In this work, we describe a paper-based Transwell assay capable of quantifying cellular invasion through an extracellular matrix. The paper-based Transwell assays generate similar datasets, with equivalent reproducibility, to commercially available Transwell assays.

A pH-Sensing Optode for Mapping Spatiotemporal Gradients in 3D Paper-Based Cell Cultures.

Paper-based cultures are an emerging platform for preparing 3D tissue-like structures. Chemical gradients can be imposed upon these cultures, generating microenvironments similar to those found in poorly vascularized tumors. There is increasing evidence that the tumor microenvironment is responsible for promoting drug resistance and increased invasiveness.

3D cellular invasion platforms: how do paper-based cultures stack up?

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.

Investigating the impacts of DNA binding mode and sequence on thermodynamic quantities and water exchange values for two small molecule drugs.

Doxorubicin and nogalamycin are antitumor antibiotics that interact with DNA via intercalation and threading mechanisms, respectively. Because the importance of water, particularly its impact on entropy changes, has been established in other biological processes, we investigated the role of water in these two drug-DNA binding events. We used the osmotic stress method to calculate the number of water molecules exchanged (Δnwater), and isothermal titration calorimetry to measure Kbinding, ΔH, and ΔS for two synthetic DNAs, poly(dA·dT) and poly(dG·dC), and calf thymus DNA (CT DNA).

Quantifying oxygen in paper-based cell cultures with luminescent thin film sensors.

Paper-based scaffolds are an attractive material for generating 3D tissue-like cultures because paper is readily available and does not require specialized equipment to pattern, cut, or use. By controlling the exchange of fresh culture medium with the paper-based scaffolds, we can engineer diffusion-dominated environments similar to those found in spheroids or solid tumors. Oxygen tension directly regulates cellular phenotype and invasiveness through hypoxia-inducible transcription factors and also has chemotactic properties.

Real-time imaging of cancer cell chemotaxis in paper-based scaffolds.

Cellular migration is the movement of cells, cultured as a monolayer; cellular invasion is similar to migration, but requires the cells to move through a three-dimensional material such as basement membrane extract or a synthetic hydrogel. Migration assays, such as the transwell assay, are widely used to study cellular movement because they are amenable to high-throughput screens with minimal experimental setup. These assays offer limited information about cellular responses to gradients in vivo because they oversimplify the threedimensional (3D) environment of a tissue.