Longitudinal in vivo bioluminescence imaging of neural stem cell-Luciferase/enhanced green fluorescent protein (NSC-Luc/eGFP) grafts. (A) In vitro characterisation of NSC-Luc/eGFP. Left, representative fluorescence microscopy image of Luciferase/eGFP-expressing NSC (NSC-Luc/eGFP) used in this study. Green colour, direct eGFP fluorescence. Middle histogram overlay, representative flowcytometric analysis of parental NSC and NSC-Luc/eGFP. Open black histogram, control background fluorescence in FL-1 green channel from parental NSC. Filled green histogram, direct eGFP fluorescence in FL-1 green channel from NSC-Luc/eGFP. Right, in vitro bioluminescence analysis of 1 × 105 parental NSC and NSC-Luc/eGFP. Data are expressed as photons/s/sr/cm2 from a 5-minute time period (± standard error of the mean (SEM), n = 4). (B) In vivo bioluminescence imaging (BLI) - image aquisition. Representative time course image showing in vivo BLI of mice grafted with 1.5 × 105 NSC-Luc/eGFP in the central nervous system (CNS). Images were acquired at day 1 (n = 25), day 3 (n = 15), day 5 (n = 15), day 7 (n = 10), day 10 (n = 5) and day 14 (n = 5) post-implantation. Regions of interest are drawn on the mouse head, where NSC-Luc/eGFP were injected, and on the mouse shoulder, considered as background signal. A representative time course image was chosen out of five mice imaged for the whole time course. (C) In vivo BLI- image analysis. Quantitative analysis of in vivo BLI analysis at day 1, 3, 5, 7, 10 and 14 post-implantation. BLI signals (in photons/s/sr/cm2) are provided as the mean (± SEM) for all mice analysed, both from the specific region of interest on the mouse head (red bars) and from the control region of interest on the mouse shoulder (blue bars). Significant differences are described in the results section.