Enhancing therapeutic efficacy of photothermal therapy using poloxamer-reduced graphene oxide and mesenchymal stem cells

Due to their heat-generating property based on exogenous energy irradiation, reduced graphene oxide particles (RGOs) have been widely used for photothermal cancer therapy. They show high absorbance for the near-infrared wavelength that is suitable for in vivo experimentation. However, enhancing the tumor-targeting efficiency and avoiding the self-aggregation of RGO to maximize the photothermal effect remain challenging. We demonstrated here that human mesenchymal stem cells (hMSCs) can deliver poloxamer conjugated RGOs (pRGOs) to target tumors. Self-aggregation limits cellular uptake and induces treatment of high particle concentrations for the photothermal effect. However, compared to RGOs, pRGOs did not show any self-aggregation. pRGOs-laden hMSCs injected intravenously to tumor-bearing mice led to significantly enhanced tumor-targeting efficiency and higher heat generation than injections of RGOs following exogenous laser irradiation. This work shows that the tumor tropism of hMSC can be applied for increased tumor-targeting efficiency with small amounts of particles. Taken together, the results indicate that combining hMSCs with pRGOs could increase the therapeutic effect in photothermal cancer therapy in a synergistic manner.