One-step Conjugation of Glycyrrhetinic Acid to Cationic Polymers for High-performance Gene Delivery to Cultured Liver Cell.

Yue Cong,Bingyang Shi,Yiqing Lu,Bingyang Shi,Bingyang Shi,Shihui Wen,Roger Chung,Dayong Jin

doi:10.1038/srep21891

Abstract

Gene therapies represent a promising therapeutic route for liver cancers, but major challenges remain in the design of safe and efficient gene-targeting delivery systems. For example, cationic polymers show good transfection efficiency as gene carriers, but are hindered by cytotoxicity and non-specific targeting. Here we report a versatile method of one-step conjugation of glycyrrhetinic acid (GA) to reduce cytotoxicity and improve the cultured liver cell -targeting capability of cationic polymers. We have explored a series of cationic polymer derivatives by coupling different ratios of GA to polypropylenimine (PPI) dendrimer. These new gene carriers (GA-PPI dendrimer) were systematically characterized by UV-vis,1H NMR titration, electron microscopy, zeta potential, dynamic light-scattering, gel electrophoresis, confocal microscopy and flow cytometry. We demonstrate that GA-PPI dendrimers can efficiently load and protect pDNA, via formation of nanostructured GA-PPI/pDNA polyplexes. With optimal GA substitution degree (6.31%), GA-PPI dendrimers deliver higher liver cell transfection efficiency (43.5% vs 22.3%) and lower cytotoxicity (94.3% vs 62.5%, cell viability) than the commercial bench-mark DNA carrier bPEI (25kDa) with cultured liver model cells (HepG2). There results suggest that our new GA-PPI dendrimer are a promising candidate gene carrier for targeted liver cancer therapy.

Highlights

Gene therapies represent a promising therapeutic route for liver cancers, but major challenges remain in the design of safe and efficient gene-targeting delivery systems
We successfully developed a new delivery system with good biocompatibility and efficient liver cell targeting capability through one-step glycyrrhetinic acid (GA) conjugation to PPI dendrimer (GA-PPI)
One should note that GA substitution is the key factor to control the gene loading/protection, cytotoxicity, targeting transfection efficiency of resulted GA-PPI

Summary

Introduction

Gene therapies represent a promising therapeutic route for liver cancers, but major challenges remain in the design of safe and efficient gene-targeting delivery systems. Cationic polymers show good transfection efficiency as gene carriers, but are hindered by cytotoxicity and non-specific targeting. We have explored a series of cationic polymer derivatives by coupling different ratios of GA to polypropylenimine (PPI) dendrimer These new gene carriers (GA-PPI dendrimer) were systematically characterized by UV-vis,1H NMR titration, electron microscopy, zeta potential, dynamic lightscattering, gel electrophoresis, confocal microscopy and flow cytometry. The success of gene therapy is largely dependent upon the development of high-performance delivery systems which can efficiently and selectively deliver therapeutic genes into target cancer cells without causing associated side-effects. The high toxicity of PPI is caused mainly by their high positive charge, which can be alleviated by surface modification of PEGlation, Glycolation and carbohydrate-coating[18] To enhance their targeting capability, these www.nature.com/scientificreports/. How to realize the alleviation of cytotoxicity and enhancement of targeting capability of PPI dendrimer via one step fabrication process is important for the development of PPI dendrimer based advanced delivery systems

Methods

Findings

Discussion

Conclusion