Imaging Cancer Cells and their Interactions Within 3D Microenvironment - a Quantitative Study using Cryo Soft X-Ray Tomography

Abstract

One of the most fundamental questions for cancer cell biologists is how the alterations of cellular morphology, as well as the organelles’ spatial re-organization, facilitate the cancer metastasis process. We are using soft x-ray tomography (SXT) to visualize and quantify all organelles in the cell in three dimensions during this collective behavior. This technique has also enabled us to account for the cell heterogeneity and to examine a large number of cells and their interactions within a created micro-environment. SXT is a non-invasive imaging technique with high spatial resolution (∼35nm). It is a quantitative imaging technology that generates high contrast views of organelles within intact cells in their near-native state. Illuminating cells with soft x-ray takes the advantage of “water-window” property that image contrast comes directly from the absorption of cell constituents. The absorption is also linear with the concentration of bio-organic molecules. Each voxel in an organelle has a denoted value called linear absorption coefficient (LAC) that can be used as a fingerprint for different organelles. We have created a 3D microenvironment using different concentrations of collagen that have resulted in different pore sizes for cancer cells (HT1080) to crawl through. With different physical limitations, we observed the distinct cellular morphologies during different states. We can quantitatively study the variaitons in nuclear size and shapes, the mitochrondria spatial distributions and volumes, the number and volume of lipid droplets and analyze the ratios between euchromatin and heterochromatin.