In vivo real-time multiphoton imaging of T lymphocytes in the mouse brain after experimental stroke.

BACKGROUND AND PURPOSE To gain a better understanding of T cell behavior after stroke, we have developed real-time in vivo brain imaging of T cells by multiphoton microscopy after middle cerebral artery occlusion. METHODS Adult male hCD2-GFP transgenic mice that exhibit green fluorescent protein-labeled T cells underwent permanent left distal middle cerebral artery occlusion by electrocoagulation (n=6) or sham surgery (n=6) and then multiphoton laser imaging 72 hours later. RESULTS Extravasated T cell number significantly increased after middle cerebral artery occlusion versus sham. Two T cell populations existed after middle cerebral artery occlusion, possibly driven by 2 T cell subpopulations; 1 had significantly lower and the other significantly higher track velocity and displacement rate than sham. CONCLUSIONS The different motilities and behaviors of T cells observed using our imaging approach after stroke could reveal important mechanisms of immune surveillance for future therapeutic exploitations.