Sonodynamic Therapy On Intracranial Glioblastoma Xenografts Using Sinoporphyrin Sodium Delivered By Ultrasound With Microbubbles

Malignant glioma is the most common intracranial tumor with high recurrence rate,high mortality and low cure rate.Sonodynamic therapy(SDT)is an emerging non-invasive treatment for cancer,which utilizes ultrasound to activate sonosensitizers accumulated in tissues and induce anti-tumor effects.At present,most of the sonodynamic therapy researches mainly focused on the treatment of extracranial tumors,while few studies investigated the effects on intracranial tumors.The primary bottleneck for drug treatment of gliomas is the presence of the blood-brain-barrier(BBB).The BBB blocks the invasion of harmful substances under the normal physiological condition and maintains the stability of the brain environment,but it also hinders most of the therapeutic drugs entering the brain and affecting the therapeutic outcomes.Focused ultrasound has the ability to deposit energy deeply into the body.Moreover,when combined with microbubbles,the BBB could be opened non-invasively and reversibly.This study proposed using sinoporphyrin sodium(DVDMS)as the sonosensitizer,which were delivered across the BBB by low-frequency focused ultrasound combined with microbubbles first and then sonodynamic therapy was performed to treat glioma.First,we investigated the uptake of DVDMS by human glioma cell line U87 MG,the time course of DVDMS accumulated in the cells,the effect of the dose of DVDMS on the intake,and the cytotoxicity of the DVDMS.The results showed that the DVDMS intake of U87 cells was significantly increased after 3 h incubation,and the intake increased with the incubation time.The higher the concentration of DVDMS makes the higher absorption of DVDMS by cells in the same incubation time.And DVDMS has no significant cytotoxicity,verifying the safety of DVDMS as the sonosensitizer.Secondly,certain ultrasound parameters were obtained.With the center frequency of 1.013 MHz,the acoustic power of 1.7 W,30% duty cycle,and 1 Hz pulse repetition frequency,the cell survival rate after in vitro SDT was 36.4%.Afterwards,ultrasound combined with microbubble effectively enhanced the delivery of DVDMS.The accumulation of DVDMS reached 3.43 times of the DVDMS alone group.Then,we established bioluminescent intracranial human glioblastoma animal models.FUS with MBs were used to induce enhanced delivery of the sonosensitizer DVDMS through the BBB to the brain tumor site first,and then the DVDMS-mediated SDT treatment was activated by low-intensity ultrasound.The in vivo efficacy of SDT using DVDMS as the sonosensitizer on nude mice bearing intracranial U87 MG-Red-Fluc human glioblastoma was evaluated.Bioluminescence imaging(BLI)was used to longitudinally monitor the tumor growth tendency.The proliferation and apoptosis of the intracranial glioblastoma were also assessed by immunohistochemical examination.It was found that after three weeks of treatment,the bioluminescence values of the tumors in the sonodynamic therapy group were significantly lower than those in the control group.Besides,the median survival time of the experiment group was 27.37% higher than of the control group.Pathological and immunohistochemical analysis showed that SDT can effectively inhibit the proliferation of tumor cells and promote cells apoptosis.The originality of this paper is as follows:DVDMS is a novel anti-cancer sonosensitizer with single component,good water solubility,low dark toxicity,and high singlet oxygen yield.Currently there is no research using DVDMS in the sonodynamic therapy for glioma.In this study,a two-step treatment strategy was proposed for the sonodynamic therapy of glioma: firstly,ultrasound was combined with microbubbles to deliver the sonosensitizer into the brain;then the animal model was treated with the same ultrasound equipment.The feasibility of this method was explored by in vitro and in vivo experiments,and the results of the study have been published in the journal Annals of Biomedical Engineering.