Bioorthogonal labeling and tracking of cells for improving the therapeutic efficacy of the cell therapeutics

Abstract

Non-invasive and precise tracking of transplanted cells within the living body is crucial for monitoring their therapeutic efficacy and in vivo fate. To this end, we have developed a bioorthogonal cell labeling and tracking strategy utilizing bioorthogonal click chemistry. First, mesenchymal stem cells and T-cells were incubated with N-azidoacetyl-D-mannosamine-tetraacylated (Ac4ManNAz) to incorporate azide (-N3) groups on the cell surface via metabolic glycoengineering. Azide groups on the cells were subsequently labeled with various cyclic alkyne-modified imaging probes, including near-infrared fluorescence (NIRF) dye and glycol chitosan nanoparticles, using chemical ligation. The labeling efficiency of bioorthogonally labeled cells was controlled by adjusting the concentrations of Ac4ManNAz and imaging probes in the cell culture condition. Significantly, bioorthogonally labeled cells demonstrated robust NIRF signals in vitro, with no significant changes in their functional properties, such as cell viability and proliferation. Using this technique, we successfully tracked the migration, distribution, and accumulation of bioorthogonally labeled mesenchymal stem cells for up to 14 days after intraparenchymal injection into a photothrombotic stroke mouse model. Additionally, bioorthogonally labeled T-cells showed therapeutic responses correlated with NIRF signals, enabling the prediction of tumor growth inhibition effect at the early stage of T-cell injection. Our studies demonstrate that bioorthogonal labeling and tracking of cell therapeutics provide high labeling efficiency and safety in vitro and in vivo, making it a promising approach for potential application in regenerative medicine and cell therapy.