Getting up early on Tuesday morning was indeed worth it, thanks to Reinhold Förster and Ronald Germain! We got the possibility to enjoy our morning coffee while watching some colourful impressive microscopy pictures and videos on cell trafficking.
Reinhold Förster introduced an impressive study to us, presenting an intralymphatic injection technique established in his lab where they inject naive T cells and analyze the homing and migration of these T cells within the thymus. Already after 4 hours they could detect T cells that entered via the efferent lymphatics into the thymus. He nicely summarized his talk stating that the supcapsular zone of the thymus serves as a mechanical filter for invading cells and that the 3D structure of the thymus leads to an arrest of cells. Followed by a crawling of the cells and a directional migration of cells into the parenchyma towards the T cell zone of the thymus. After this directional migration a random migration of thymocytes occurs.
He reported that CCR7 deficiency leads to an arrest of cells at the supcapsular region instead of a migration towards the T cell zone. In addition CCR4 and CCR8 play a role in the translocation whereas CXCL3 does not.
He presented some impressive pictures showing the speeding up in migration and the straight directionality of their migration towards the T cell zone. Further a SeTau staining showed a cell migration along the condroits towards the T cell zone, serving as a kind of walking matrix. Selectins (E-, L-, P-) as well as CD18 and PLVAP do not play a role in cell adhesion in this process of translocation, CD44 was shown to be crucial for homing but not for translocation.
Ronald Germain presented an impressive multi colour Histo-Cytometry assay which allows quantification of expression in a spatial context combining advantages of Histology studies and Cytometry techniques.
In his lab they used laser-induced damaged to get a local dermis injury. They could show that neutrophils migrate towards the side of damage and show a swarming around the injured side. They show that LTB4 and LTB4R are essential for the swarming behaviour. Further he nicely showed that the neutrophils arrest at the injured side but as a static swarm, but a second laser-induced damage in proximity to the first one could reactivate the neutrophils and induce a new swarming towards the second injured side.
His lab used the Histo-Cytometry technique for several organs such as lung, lymphnode or intestine etc. The resolution of the videos was impressive as it was not only possible to zoom-in down to single cells to analyze their expression profiles but to also be able to visualize the entire organ at the same time. This technique offers great opportunities in the expression analysis with respect to the spacial localisation of cells.