Preparation Of Fingolimod-loaded Smart Drug Delivery System And Its Application In The Treatment Of Thyroid Cancer

Fingolimod(FTY720)can target multiple signal pathways to regulate cell proliferation,death,movement,angiogenesis and other physiological processes.Recent studies have shown that FTY720 has been used to treat various tumors.So far,there is no report of FTY720 for thyroid cancer(TC)treatment.Therefore,this study designed two new stmulus-responsive nano-drug carriers loaded with FTY720 for TC treatment.1.Study on pH-responsive nanoparticles(NPs)and their anti-cancer activitiesSilk fibroin(SF)was used as a shell to cover selenium nanoparticles(Se NPs),then HAIYPRH(T7)peptides were grafted onto the surface of SF-Se NPs,and FTY720 was loaded into T7-SF-Se NPs.The experimental results showed that the prepared NPs were spherical with an average diameter range of 100-150 nm.They had good stability,and the encapsulation efficiency was 71.95%.The effects of different pH,ionic strength and temperature conditions on the release of FTY720 from FTY720@T7-SF-Se NPs were studies.The release of FTY720 from NPs was pH-dependent,and the release of FTY720 was accelerated in an acidic environment.The release amount and rate of FTY720 was increased with the increase of NaCl concentration when the temperature(25℃)and pH(pH7.4)were fixed.The release amount and rate of FTY720 was also increase with the increase of temperature at pH7.4.In the cytotoxicity study,FTY720@T7-SF-Se NPs showed low toxicity to 3T3 at a concentration range of 10～50 g/mL.In addition,the in vitro hemolysis rates of SF-Se,FTY720@SF-Se and FTY720@T7-SF-Se NPs were all lower than 5%.Both in vitro and in vivo biodistribution studies demonstrated that FTY720@T7-SF-Se NPs could effectively accumulate in the tumor region,thereby enhancing the ability to kill cancer cells.Anti-cancer studies in vitro and in vivo further confirmed that FTY720@T7-SF-Se NPs had high anti-tumor activities.Studies of histology and immunohistochemistry showed that FTY720@T7-SF-Se NPs had low toxicity to the major organs of tumor-bearing mice,indicating the prepared NPs has good biocompatibility in vivo.In summary,FTY720@T7-SF-SeNPs has great potential as a safe and effective anti-tumor drug for TC therapy.2.Study on ultrasound-responsive nanobubbles(NBs)and their anti-cancer activities as well as ultrasound imagingIn this study,T7 peptide modified liposome was used as the outer shell,while perfluoropentane(PFP)and FTY720 were used as the core,to construct ultrasound-responsive FTY720@PFP/T7-NBs for TC treatment.The experimental results showed that the prepared NBs were spherical with a diameter of about 180-210 nm.They had good stability and the zeta potential was-45 mV.The drug loading rate and encapsulation rate of the prepared NBs were 9.03%and 87.34%,respectively.With the low-intensity focused ultrasound(LIFU)treatment,the efficiency of FTY720 released from FTY720@PFP/T7-NBs was prompted.The higher the LIFU power,the stronger the ability of NBs to release FTY720.Cytotoxicity studies show that the prepared NBs had low toxicity to 3T3 cells,while they showed strong toxicity to TC cells with LIFU treatment.The results of hemolysis study showed that the hemolysis rate of the NBs(10-100 g/mL)was less than 5%.The animal study further confirmed that FTY720@PFP/T7-NBs has high anti-tumor activity with LIFU treatment.The prepared FTY720@PFP/T7-NBs showed enhanced ultrasound imaging effects with the LIFU promotion both in vitro and in vivo,indicating that FTY720@PFP/T7-NBs has great potential as enhanced ultrasound contrast agents in the ultrasound imaging.Immunohistochemical analysis showed that FTY720@PFP/T7-NBs had low toxicity to the major organs of tumor-bearing mice with or without LIFU-mediated conditions,indicating the prepared NBs has good biocompatibility in vivo.In summary,FTY720@PFP/T7-NBs with LIFU treatment,can be served as multifunctional drug delivery platform for TC treatment,and provides a new strategy for tumor visualization through ultrasound imaging.