Aim: Qtracker(®)800 Vascular labels (Qtracker(®)800) are promising biomedical tools for high-resolution vasculature imaging; their effects on mouse and human endothelia, however, are still unknown.
Materials & methods: Qtracker(®)800 were injected in Balb/c mice, and brain endothelium uptake was investigated by transmission electron microscopy 3-h post injection. We then investigated, in vitro, the effects of Qtracker(®)800 exposure on mouse and human endothelial cells by calcium imaging.
Results: Transmission electron microscopy images showed nanoparticle accumulation in mouse brain endothelia. A subset of mouse and human endothelial cells generated intracellular calcium transients in response to Qtracker(®)800.
Conclusion: Qtracker(®)800 nanoparticles elicit endothelial functional responses, which prompts biomedical safety evaluations and may bias the interpretation of experimental studies involving vascular imaging.
Keywords: calcium imaging; cytosolic calcium transients; human umbilical vein endothelial cells; mouse brain endothelium; nanoparticle uptake; nanoparticles; transmission electron microscopy.