<p>Fluorescence images of the brains were taken at the indicated times. (A) In the absence of tumor, the fluorescent signals of hAT-MSCs (blue) are weakened at 2 weeks and are not detectable at 3 weeks. (B) <i>In vivo</i> sequential tracking was performed by injecting both NEO-LIVE 675-labeled BTICs (red) and NEO-LIVE 797-labeled hAT-MSCs (blue). hAT-MSCs gradually migrate toward the tumor site, and strong fluorescent signals are observed at 4 weeks post-injection at the tumor site. (C) Mice were injected the NEO-LIVE 797-labeled hAT-MSCs or HFF1. Representative <i>in vivo</i> fluorescence images show that the HFF1 signals are decreased or fade out. (D) On the contrary, the hAT-MSC signals are widened at all BTIC-derived mouse brain tumor sites at 3 weeks post-injection when compared with HFF1 cells. The color bar indicates radiant efficiency.</p
