Mesenchymal stem cells transporting black phosphorus-based biocompatible nanospheres: Active trojan horse for enhanced photothermal cancer therapy

As potential carriers for specifically transporting photothermal agents to tumors, mesenchymal stem cells (MSC) would enhance their photothermal therapeutic effects. However, a biocompatible and biodegradable nanoscale photothermal agent, which hardly affects the tumor tropism of MSC, is still urgently needed. This study reports an effective therapeutic platform based on MSC loaded with poly (lactic-co-glycolic acid)/black phosphorus quantum dots (PLGA/BPQDs) for targeted photothermal therapy of U251 glioma tumor cells. PLGA/BPQDs could not only be effectively uptaken by the MSC, but also stably maintained in the MSC for as long as 3 d. PLGA/BPQDs-loaded MSC exhibited changeless high tumor-tropic ability due to the exceptional biocompatibility of PLGA/BPQDs. In vitro results showed that PLGA/BPQDs can be transported from MSC to U251 cells, where U251 cells are killed after irradiation. In vivo results demonstrated that MSC@PLGA/BPQDs can efficiently tend the U251 glioma tumor and showed much longer retention times at the tumor site than PLGA/BPQDs alone. Finally, MSC@PLGA/BPQDs, as an active trojan horse, demonstrated enhanced photothermal effectivity on the U251 glioma tumor in vivo.