Fluorescent Tracers for In Vivo Imaging of Lymphatic Targets

Abstract

The lymphatic system continues to gain importance in a range of conditions, and therefore, imaging of lymphatic vessels is becoming more widespread for research, diagnosis, and treatment. Fluorescent lymphatic imaging offers advantages over other methods in that it is affordable, has higher resolution, and does not require radiation exposure. However, because the lymphatic system is a one-way drainage system, the successful delivery of fluorescent tracers to lymphatic vessels represents a unique challenge. Each fluorescent tracer used for lymphatic imaging has distinct characteristics, including size, shape, charge, weight, conjugates, excitation/emission wavelength, stability, and quantum yield. These characteristics in combination with the properties of the target tissue affect the uptake of the dye into lymphatic vessels and the fluorescence quality. Here, we review the characteristics of visible wavelength and near-infrared fluorescent tracers used for in vivo lymphatic imaging and describe the various techniques used to specifically target them to lymphatic vessels for high-quality lymphatic imaging in both clinical and pre-clinical applications. We also discuss potential areas of future research to improve the lymphatic fluorescent tracer design.

Biodegradable hollowed mesoporous SeO2 nanoplatform loaded with indocyanine green for simultaneous NIR II fluorescence imaging and synergistic breast carcinoma therapy

“…First, ICG is generally rapidly cleared from the blood circulatory system (blood half-life, approximately 3 min) ( Dorr and Pollack, 1989 ; Saxena et al, 2003 ). Second, due to its amphiphilic properties, ICG non-covalently interacts with various proteins, including lipoproteins and human serum albumin, and forms aggregates via physical mechanisms ( Patonay et al, 2004 ; Russell et al, 2022 ). Third, ICG lacks tumor targeting capacity, resulting in low signal to background ratios ( Zheng et al, 2012 ; Keating et al, 2016 ).…”

Endothelial Erg Regulates Expression of Pulmonary Lymphatic Junctional and Inflammation Genes in Mouse Lungs Impacting Lymphatic Transport

“…Next, to determine if Erg downregulation in pulmonary lymphatics impacts fluid drainage, 2,000 kDa FITC-Dextran was injected intratracheally at a concentration of 10 mg/kg b.w 26 . The quantity of dye retention in lungs v/s in circulation to axial lymph node and blood was monitored after 30 mins post injection (Fig 2g).…”

Imaging peripheral lymphatic dysfunction in chronic conditions

“…Lymphatic imaging of preclinical models using fluorescent contrast agents or dyes has been demonstrated over the years. For a more comprehensive review of these approaches and more particular of the various fluorescent contrast agents used preclinically, (i.e., most are not approved for human use) see ( Russell et al, 2022 ).…”