Whole-body tracking of single cells via positron emission tomography

Abstract

In vivo molecular imaging can measure the average kinetics and movement routes of injected cells through the body. Yet owing to the non-specific accumulation of the contrast agent and its efflux from the cells, most such imaging methods suffer from inaccurate estimations of the distribution of the cells. Here, we show that single human breast cancer cells loaded with mesoporous silica nanoparticles concentrating the ⁶⁸Ga radioisotope and injected in immunodeficient mice can be tracked in real time from the pattern of annihilation photons detected by positron emission tomography, with respect to anatomical landmarks derived from X-ray computed tomography. We show that the cells travelled at an average velocity of 50 mm/s and arrested in the lungs two-to-three seconds after tail-vein injection in the mice, which is consistent with the blood-flow rate. Single-cell tracking could be used to determine the kinetics of cell trafficking and arrest during the earliest phase of the metastatic cascade, the trafficking of immune cells during cancer immunotherapy, and the distribution of cells after transplantation.

Abstract

One-sentence editorial summary:

The travelling kinetics of single cells loaded with mesoporous silica nanoparticles concentrating the ⁶⁸Ga radioisotope and injected in mice can be tracked in real time from the pattern of coincident gamma-rays detected by positron emission tomography.