Analyzing Leukocyte Extravasation by 4D Mathematical Image and Motion Analysis

Frames taken from a 3D live imaging video of a postcapillary venule in the cremaster with extravasating leukocytes. Endothelial contacts are stained for PECAM (red), leukocytes are stained genetically by expressing GFP (green). The arrow marks a neutrophil in the process of junctional diapedesis (upper row) or the “hole” that becomes visible in the junctions at this site (bottom row) when only the red channel is depicted. Times are given above in minutes; scale bar=20μm.
© Dietmar Vestweber, Christoph Brune

Principal investigators: Dietmar Vestweber, Christoph Brune
Project time: 07/2013 - 06/2015
Project code: FF-2013-33

This project is focused on the cell mechanics of leukocyte extravasation in vivo, which is analyzed by 4D mathematical analysis of fluorescence live microscopy data in vivo. Leukocytes seem to take two different pathways to overcome the barrier of endothelial cell layers: 1.) they can move through the junctions between endothelial cells (paracellular) or 2.) through the body of endothelial cells (transcellular). By directly analyzing leukocyte extravasation in vivo we analyze whether the diapedesis of leukocytes differs depending on the type of leukocytes, the type of blood vessels or the type of tissue that is investigated. In addition, we want to analyze whether the mechanical constraints of leukocyte transmigration are different depending on which route of transmigration is used. Visual limitations of 4D fluorescence live microscopy data and a careful quantitative analysis of the experiments, require a sophisticated 4D mathematical modeling that is tailored to the needs of leukocyte transmigration and goes beyond commercially available 3D imaging and tracking software.

Podcast: Tracking Cells in Motion – How Do Immune Cells Break Down Barriers When Migrating?