Echogenic PEGylated PEI-Loaded Microbubble As Efficient Gene Delivery System

Abstract

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)-SS-polyethylenimine-loaded microbubbles (PSP@MB) as an ultrasound theranostic and redox-responsive 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 with PSP@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 ultrasound-mediated gene delivery system could efficiently target CSCs.

Keywords:

• ultrasound
• PEGylated PEI-loaded microbubble
• cancer stem cell
• gene delivery

Acknowledgements

This work is supported by the Research Projects of National Natural Science Foundation of China (No. 81671707, 81527803, 81420108018, 81971621), National Key R&D Program of China (No.2018YFC0115900), the Young Scientists Fund of the National Natural Science Foundation of China (81901764), the Natural Science Foundation of Guangdong Province (No. 2018A030313678), the Natural Science Foundation of Guangdong Province (No. 2016A030311054), the Zhejiang Science and Technology Project (No. 2019C03077), the Research Projects of Guangzhou Technology Bureau (No. 201607010201), the PhD Research Startup Foundation of the Third Affiliated Hospital of Guangzhou Medical University (No. 2018B04), the Research Fund for Lin He’s Academician Workstation of New Medicine and Clinical Translation, the Shenzhen Health and Family Planning System Scientific Research Project (No. 201607040), the 2018 Youth Scientific Research Project of the Third Affiliated Hospital of Guangzhou Medical University (No. 2018Q28, No. 2018Q03), and the Medical Science and Technology Research Fund Project of Guangdong Province (No. B2019136). Scientific and Technological Livelihood Projects of Liwan district (No. 201904003).

Disclosure

The authors report no conflicts of interest in this work.