Validation of a device for fluorescence sensing of rare circulating cells with diffusive light in an optical flow phantom model.

Detection and quantification of rare circulating cells in biological tissues is an important problem and has many applications in biomedical research. Current methods normally involve extraction of blood samples and counting of cells ex vivo, or the use of microscopy-based fluorescence in vivo flow cytometry. The goal of this work is to develop an instrument for non-invasively enumerating very rare circulating cells in small animals with diffuse light with several orders of magnitude sensitivity improvement versus current approaches. In this work, we describe the design of our system and show that single, fluorescent microspheres can be detected in limb-mimicking optical flow phantoms with varying optical properties chosen to simulate in vivo conditions. Further, we demonstrate single cell counting capabilities using fluorescently (Vybrant-DiD) labeled Jurkat and Multiple Myeloma cells. Ongoing work includes in vivo testing and characterization of our system in mice.