Extended Data Fig. 7: Nalm-6 cells do not invade via diapedesis through the leptomeningeal blood–brain barrier.
From: Leukaemia hijacks a neural mechanism to invade the central nervous system
a, Graphic of thinned skull window and video-rate intravital confocal microscopy approach used to image the leptomeningeal vasculature at various time points after engraftment with ALL cells. b, Representative still images from video-rate intravital microscopy analysis of leptomeningeal and superficial cerebral vasculature (red) at 10 min after intravenous Nalm-6 engraftment (full video presented in Supplementary Videos 1, 2). Nalm-6 cells (green) are observed in circulation. n = 12 mice imaged on day 0 after engraftment. c, Series of still images of leptomeningeal and superficial cerebral vasculature at 45 min after intravenous Nalm-6 engraftment. A Nalm-6 cell is observed adherent to the luminal side of a leptomeningeal vessel (white arrowhead). A second Nalm-6 cell is observed rolling along the luminal wall of a leptomeningeal vessel (blue arrowhead) (see Supplementary Video 3). No invasion via diapedesis was observed during the entirety of each 2–4-h long imaging session on the day of engraftment. n = 12 mice imaged on day 0 after engraftment. d, Still images of the leptomeningeal and superficial cerebral vasculature 12 days after Nalm-6 engraftment. No Nalm-6 cells were observed in circulation or within the leptomeningeal tissue (see Supplementary Video 4; n = 4 mice, days 2, 4, 7 and 12 after engraftment). e, Representative images from intravital confocal microscopy of the calvarial bone marrow at 2 h after Nalm-6 engraftment. Numerous Nalm-6 cells (white arrowheads) are seen to have invaded through the bone marrow vasculature soon after intravenous engraftment. n = 15 mice. f, Series of still images of the z plane of the leptomeningeal and superficial cerebral vasculature of a leukaemic mouse engrafted with Nalm-6 cells at disease end point. n = 7 mice, days 37–39 after engraftment. Nalm-6 cells are observed in circulation (white arrowheads), but no cells are observed to invade (see Supplementary Video 5).
