In Vivo Imaging of Exosomes Labeled with NIR-II Polymer Dots in Liver-Injured Mice

Mesenchymal stem cell-derived exosomes (MSC-Exos) are emerging as a promising platform for treating various intractable diseases and organ injuries. Monitoring their migration, homing, and therapeutic capability in vivo is essential to develop exosome-based theranostics. Here, we designed fluorescent semiconductor polymer dots (Pdots) in the second near-infrared window (NIR-II) for bright labeling and tracking of MSC-Exos. Glucose-coated Pdots (Pdots-Glu) were able to label MSC-Exos without changing their biological properties. The NIR-II fluorescent Pdots allow for high labeling brightness and long-term in vivo tracking of MSC-Exos. We investigated the biodistributions and therapeutic functions of these labeled MSC-Exos in liver-resected mice. In vivo and ex vivo imaging demonstrated that the Pdot-labeled MSC-Exos injected via the tail vein mainly accumulated in the residual liver tissue. In terms of the therapeutic effect, MSC-Exos may accelerate postoperative liver function recovery by inhibiting inflammatory responses, promoting cell proliferation, and resisting apoptosis. Our results indicated that MSC-Exos therapeutic systems hold promising applications in liver regenerative medicine.

Automated summary

This study developed fluorescent semiconductor polymer dots (Pdots) for labeling and tracking mesenchymal stem cell-derived exosomes (MSC-Exos). The labeled MSC-Exos mainly accumulated in the residual liver tissue and showed therapeutic effects in terms of inhibiting inflammatory responses, promoting cell proliferation, and resisting apoptosis, which could accelerate postoperative liver function recovery.