Chun Liufu1 Yue Li1 Jiawei Tu1 Hui Zhang1 Jinsui Yu1 Yi Wang1 Pintong Huang2 Zhiyi Chen1
1Department of Ultrasound Medicine, Laboratory of Ultrasound Molecular Imaging, The Third Affiliated Hospital of Guangzhou Medical University, Experimental Center, The Liwan Hospital of The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510000, People’s Republic of China; 2Department of Ultrasound, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, People’s Republic of China
Background: Cancer stem cells (CSCs) are responsible for cancer therapeutic resistance and metastasis. To date, in addition to surgery, chemotherapy, and radiotherapy, gene delivery has emerged as a potential therapeutic modality for ovarian cancer. Efficient and safe targeted gene delivery is complicated due to the tumor heterogeneity barrier. Ultrasound (US)-stimulated microbubbles (MBs) have demonstrated a method of enabling non-invasive targeted gene delivery.
Purpose: The purpose of our study was to show the utility of poly(ethylene glycol)-SSpolyethylenimine-loaded microbubbles (PSP@MB) as an ultrasound theranostic and redoxresponsive agent in a gene delivery system. Patients and methods: PSP nanoparticles were conjugated to the MB surface through biotin–avidin linkage, increasing the gene-loading efficiency of MB. The significant increase in the release of genes from the PSP@MB complexes was achieved upon ultrasound exposure. The positive surface charge in PSP@MB can condense the plasmid through electrostatic interactions; agarose-gel electrophoresis further confirmed the ability of PSP@MB to condense plasmids. The morphology, particle sizes and zeta potential of PSP@MB were characterized by transmission electron microscopy and dynamic light scattering. Results: Laser confocal microscopy showed that the combination of ultrasound with PSP@MB could promote the cellular uptake of plasmids. Plasmids which encode enhanced green fluorescence protein (EGFP) reporter genes or luciferase reporter genes were delivered to CSCs in vitro and to subcutaneous xenografts in vivo via the combination of ultrasound withPSP@MB. Gene transfection efficiency was evaluated by fluorescence microscopy and In Vivo Imaging Systems. This study demonstrated that the combination of ultrasound with
PSP@MB can remarkably promote gene delivery to solid tumors as well as diminishing the toxicity towards normal tissues in vivo. The combination of PSP@MB and the use of ultrasound can efficiently enhance accumulation, extravasation and penetration into solid tumors. Conclusion: Taken together, our study showed that this novel PSP@MB and ultrasoundmediated gene delivery system could efficiently target CSCs.
Keywords: ultrasound, PEGylated PEI-loaded microbubble, cancer stem cell, gene delivery