Fig. 8

In vivo 2P imaging of new blood vessel sprouting and functional vascular networks after TBI injury. A Visualization of tdTomato-expressing individual endothelial cells (arrows) in microvascular networks labeled by the fluorescein-dextran-stained blood plasma in a non-injured Tie2-Cre; Ai9 mouse brain. B Consistent with in vivo miniscope imaging, 2P imaging identifies newly generated microvessels (tdTomato genetically labeled) in a Tie2-Cre; Ai9 mouse shortly (4 days) after injury. These vessels are not yet functional as they are not perfused with blood (FITC, green) (arrowheads). C, D 2P imaging of the injury area at two cortical depths in a mouse at 15 dpi. There were extensive newly re-generated microvessels at superficial cortical depths (175–200 µm; from cortical surface) that are not readily apparent at greater cortical depths. Note the tortuous nature of new microvessels. E In sham control animals, Tie2-EGFP co-localizes with DiI (red) vessel painted vascular elements (left panel). At 1 dpi there is a dramatic reduction in vessels in the injury zone (dotted line zone, middle) with new vessels (solid arrow) and newly perfused vessels (DiI + GFP, arrowhead) observable in the injury area. At 7 dpi there is a dramatic increase in the number of perfused and non-perfused (arrows) vessels within and adjacent to the injury site (right). Note the increased density and tortuosity of the new vessels at 7 dpi compared to sham