MIVFC · Development of a multichannel in vivo flow cytometer for the dynamic monitoring of circulating cells

We propose the development of a novel multichannel in vivo flow cytometer for the dynamic monitoring of multiple cell populations, such as tumor-associated cells or leukocytes, in the circulation of mice, for extended periods of time and without the need to extract blood samples. The design of the system is based on the confocal excitation and detection of fluorescently labelled cells as they flow through a blood vessel that is simultaneously probed by three lasers at different wavelengths. The feasibility and instrument sensitivity for detecting and enumerating cells in circulation will be investigated using both fluorescent microspheres and fluorescently labeled red blood cells that will be isolated from mouse whole blood samples. The ability of the system to track circulating cells in real time and in a non-invasive manner, will thus open up enormous possibilities for new investigations into the mechanisms that govern the complex trafficking and tissue interactions of these cells in a variety of clinical and biological fields such as cancer, stem cell biology and immunology. The system will also be able to measure flow velocities in vivo, in order to account for changes in circulating cell numbers that arise from changes in blood flow rate. We further propose to utilize the novel system in the dynamic monitoring of circulating cancer cells in an animal model of multiple myeloma. Fluorescently labeled multiple myeloma cells, obtained from cell cultures, will be injected in the circulation of mice to determine the instrument detection sensitivity as well as to assess the system capabilities in monitoring changes in the circulating cancer cell numbers due to tumor growth or following therapeutic intervention. The ability to quantitatively determine changes in these circulating cancer cell numbers in an in vivo manner can potentially be utilized to assess tumor burden in animals in order to track disease progression and monitor response to therapy.