Enhanced Tumor Treatment Using Biofunctional Indocyanine Green-Containing Nanostructure by Intratumoral or Intravenous Injection

Abstract

Indocyanine green (ICG) is a conventional dye that can be used in clinical near-infrared (NIR) imaging, and it is also an effective light absorber for laser-mediated photothermal therapy. However, applications of ICG were limited due to its fast degradation in aqueous media and quick clearance from the body. Herein, an ICG-containing nanostructure, ICG-PL-PEG, was developed for photothermal therapy, which was self-assembled by ICG and phospholipid-polyethylene glycol (PL-PEG). Our in vitro and in vivo experiments demonstrated that ICG-PL-PEG suspension was more efficient in producing a NIR-dependent temperature increase than ICG alone, due to the increase of ICG monomers from the addition of PL-PEG to match the central wavelength of the 808 nm laser. When conjugated with integrin α_vβ₃ monoclonal antibody (mAb), ICG-PL-PEG could be selectively internalized and retained in target tumor cells. Irradiation of an 808 nm laser after intravenous administration of ICG-PL-PEG-mAb resulted in tumor suppression in mice, while ICG alone had only limited effect. This is the first time an ICG-containing nanostructure has been used through systemic administration to achieve an efficient in vivo photothermal effect for cancer treatment. Therefore, ICG-PL-PEG could be used as a fluorescent marker as well as a light-absorber for imaging-guided photothermal therapy. All the components of ICG-PL-PEG have been approved for human use. Therefore, this unique ICG-containing nanostructure has great potential in clinical applications.