High resolution imaging of the lymphatic vascular system in living mice/rats using dual-modal polymer dots

Noninvasive, repeated, and high-resolution imaging of the lymphatic vascular system plays an important role in studying the development and function of lymphatics. However, conventional imaging modality such as magnetic resonance imaging (MRI) and X-ray lymphangiography shows insufficient temporal and spatial resolution and can only visualize large lymphatic vessels. Herein, we developed polymer dots as a novel lymphatic agent for simultaneously imaging the lymphatic capillary plexus and collecting lymphatic vessels in living mice/rats at a fast temporal resolution and high spatial resolution by combination with probe-based confocal laser endomicroscopy (pCLE). The imaging effect was verified by whole-body near-infrared fluorescence and photoacoustic imaging as well as ex vivo two-photon microscope imaging. Our study provides a novel approach for using polymer dots for high-resolution lymphatic vascular imaging in small animals.