Fig. 8: The VE-cadherin-GFP reporter mouse allows for in vivo visualization of alterations in leptomeningeal CNS zonations during neuroinflammation.

A Representative images of the spinal cord window 2P-IVM imaging of VE-cadherin-GFP knock-in reporter mice suffering from aEAE. Before a spinal cord window preparation, a tracer-filled cannula was implanted into the cisterna magna. During 2P-IVM, the mice were infused with 2.5 µl of either 3 kDa or 10 kDa, or 40 kDa TRITC dextran or TRITC BSA at a rate of 1 µl/min using a syringe pump. XY time-lapse sequence of a 400 µm × 400 μm scan field at a depth of 160–220 µm and 81–111 z-projections with 2 µm spacing were acquired for 45 mins. The dura mater is visible in blue due to the second-harmonic generation of the collagen type 1 fibers in the dura. Arachnoid mater (A.M., highlighted by a dashed line) and pia mater (highlighted by a dashed/dotted line) are visible in green due to the VE-cadherin expression. Injected tracer is seen in red. YZ MIP of the meningeal layers of the spinal cord of a VE-cadherin GFP knock-in reporter mouse suffering from aEAE imaged at the onset of the disease (days 13–15 p.i., clinical score +) are shown. At 0 min, no tracer (red) is seen. At 45 min, the 3KDa TRITC dextran (red) is seen in the dorsal vein (DV) and above the dura mater (blue), The 10- and 40-kDa TRITC dextran as well as the TRITC-BSA tracer (red) crossed the pia mater but not the arachnoid mater. Images are representative of three mice per tracer. B Graphs show the longitudinal quantification of the mean fluorescence intensity of the injected tracer in the segmented volumes from the spinal cord meningeal cross-sections shown in Fig. 7B. Data are normalized to the highest MFI value observed in the SAS after background signal substruction. Background signal was determined as the average of fluorescence signals observed in all segmented volumes prior to tracer injection. Each graph shows the full quantification of one mouse. Source data are provided as a Source Data file.