Fig. 5
From: Response of the neurovascular unit to brain metastatic breast cancer cells
Interaction of metastatic cells with astrocytes and proliferation in the brain parenchyma. a: Two-photon microscopy z-projections indicating a metastatic breast cancer cell (green) breaking the glia limitans perivascularis. SR101-positive astrocytes are marked in red; asterisks indicate cell bodies of astrocytes. Capillaries are delineated by end-feet of astrocytes; arrow indicates disruption of the continuity in the glia limitans during extravasation of the tumour cell. b: Transmission electron micrograph showing an extravasated tumour cell attached to the extraluminal surface of a cerebral capillary (day 5). Inset (1) highlights astrocyte end-foot (arrow) between the tumour cell and the capillary endothelium. c: Representative confocal z-projections showing GFAP-positive astrocyte end-feet covering capillaries in initial phases of diapedesis of metastatic cells. Red = tumour cells (tdTomato), green = endothelium (YFP), blue = nuclei (Hoechst), grey = GFAP. d: Confocal z-projection showing AQP4-positive astrocyte end-feet co-opted by extravasated metastatic cells. Merged image of blue (nuclei), green (endothelium), red (tumour cells) and grey (AQP4) channels. e: Astrocytes expelled from the growing metastatic lesion on day 10 after inoculation, as shown in a two-photon z-projection image. Red = astrocytes (SR101), green = tumour cells (EmGFP). f: AQP4-positive astrocyte end-feet gradually retracted from the capillary wall to the surface of the metastatic tumour. Confocal z-projection of metastatic lesions from the brain of an animal on day 10. Red = tumour cells (tdTomato), green = endothelium (YFP), blue = nuclei (Hoechst), grey = AQP4. Arrows show vascular AQP4 staining, dotted arrows indicate absence of vascular AQP4 staining, while arrowheads point to AQP4 staining on the surface of the tumour. g: Intact TJs in vessels co-opted by growing metastatic tumours on day 10 after, as shown in a confocal z-projection image. Red = tumour cells (tdTomato), green = endothelium (YFP), blue = nuclei (Hoechst), grey = claudin-5