Quantitative imaging of lymphatic function with liposomal indocyanine green

Area of Science:

• Biomedical imaging
• Optical imaging
• Lymphatic system research

Background:

• Lymphatic vessels are crucial in cancer progression and lymphedema.
• Accurate methods for measuring lymphatic flow are needed for new therapies.
• Current indocyanine green (ICG) imaging has limitations due to instability and rapid venous uptake.

Purpose of the Study:

• To develop and evaluate a novel liposomal formulation of ICG (LP-ICG) for improved lymphatic imaging.
• To assess LP-ICG's stability, fluorescence properties, and uptake by lymphatic vessels.
• To quantify lymphatic flow in preclinical models using LP-ICG near-infrared imaging.

Main Methods:

• Development of a liposomal formulation of ICG (LP-ICG).
• Intradermal injection of LP-ICG in mice for lymphatic visualization.
• Assessment in a genetic mouse model of lymphatic dysfunction.
• Application in a melanoma mouse model with VEGF-C expression for flow quantification.

Main Results:

• LP-ICG demonstrated improved stability, enhanced fluorescence, and longer wavelength properties.
• LP-ICG was specifically taken up by lymphatic vessels, visualizing deep lymph nodes.
• In lymphatic dysfunction models, LP-ICG showed impaired lymph node enhancement and slower clearance.
• Near-infrared imaging with LP-ICG quantified lymphatic flow, revealing increased flow with VEGF-C tumors and decreased flow with higher tumor burden.

Conclusions:

• LP-ICG offers a superior method for quantitative lymphatic imaging.
• This technique can facilitate preclinical studies of lymphatic function.
• LP-ICG holds potential for imaging lymphedema and improving sentinel lymph node detection in cancer.