1 research outputs found
Effect of Dye and Conjugation Chemistry on the Biodistribution Profile of Near-Infrared-Labeled Nanobodies as Tracers for Image-Guided Surgery
Advances
in optical imaging technologies have stimulated the development of
near-infrared (NIR) fluorescently labeled targeted probes for use
in image-guided surgery. As nanobodies have already proven to be excellent
candidates for molecular imaging, we aimed in this project to design
NIR-conjugated nanobodies targeting the tumor biomarker HER2 for future
applications in this field and to evaluate the effect of dye and dye
conjugation chemistry on their pharmacokinetics during development.
IRDye800CW or IRdye680RD were conjugated either randomly (via lysines)
or site-specifically (via C-terminal cysteine) to the anti-HER2 nanobody
2Rs15d. After verification of purity and functionality, the biodistribution
and tumor targeting of the NIR-nanobodies were assessed in HER2-positive
and -negative xenografted mice. Site-specifically IRDye800CW- and
IRdye680RD-labeled 2Rs15d as well as randomly labeled 2Rs15d-IRDye680RD
showed rapid tumor accumulation and low nonspecific uptake, resulting
in high tumor-to-muscle ratios at early time points (respectively
6.6 ± 1.0, 3.4 ± 1.6, and 3.5 ± 0.9 for HER2-postive
tumors at 3 h p.i., while <1.0 for HER2-negative tumors at 3 h
p.i., <i>p</i> < 0.05). Contrarily, using the randomly
labeled 2Rs15d-IRDye800CW, HER2-positive and -negative tumors could
only be distinguished after 24 h due to high nonspecific signals.
Moreover, both randomly labeled 2Rs15d nanobodies were not only cleared
via the kidneys but also partially via the hepatobiliary route. In
conclusion, near-infrared fluorescent labeling of nanobodies allows
rapid, specific, and high contrast <i>in vivo</i> tumor
imaging. Nevertheless, the fluorescent dye as well as the chosen conjugation
strategy can affect the nanobodies’ properties and consequently
have a major impact on their pharmacokinetics