Synthesis of aliphatic polycarbonate for siRNA delivery in cancer therapy

INTRODUCTIONGene therapy has attracted increasing attention worldwide as prominent strategy to treat diseases at the gene level. While therapeutic gene has reached clinical evaluation, their administration as a drug is very... [ view full abstract ]

INTRODUCTION

Gene therapy has attracted increasing attention worldwide as prominent strategy to treat diseases at the gene level. While therapeutic gene has reached clinical evaluation, their administration as a drug is very challenging because of their rapid clearance from the bloodstream and the lack of tissue selectivity.

Synthetic polymers have become a well-known solution to overcome these issues owing to the ease of synthesis and their ability to drive genetic materials toward targeted cells. Aliphatic poly(carbonate)s (APCs) are biocompatible and biodegradable^1,2 and they constitute an excellent family on this purpose

MATERIALS AND METHODS

In this work, APCs are synthetized by ring-opening polymerization (ROP) using a metal-free and non-toxic catalyst³. The tailoring of the polymer is done using monomers carrying the desired function. The obtained block copolymers should over-come biological barriers as the endosomal escape, the gene loading or the cell internalization. PEGylated copolymers are also considered and compared with the hydrophobic one.

Monomers are synthetized from bis-MPA synthon according to well-established procedures¹. The polymerization is carried out in CH₂Cl₂ in the presence of DBU with an initial monomers concentration of 1 M. The reaction is performed under protected atmosphere (glove box) during 4 hours at ambient temperature using PEO (hydrophilic) or BzOH (lipophilic) (macro-)initiators.

Polymers are characterized by ¹H-NMR in CDCl₃ and SEC in THF/NEt₃. The association polymer – gene (polyplexe) is evaluated in terms of physico-chemistry (size and zeta potential), siRNA incorporation, cellular transfection and mRNA shut-down.

RESULTS AND DISCUSSION

The results demonstrate that the introduction of guanidinum and morpholino groups in the composition led to a powerful polymer vector for siRNA delivery⁴ offering an excellent alternative to the toxic golden standard

poly(ethyleneimine). The presence of a hydrophilic tail has a strong impact on gene release and knock down efficiency (PEG dilemma)⁵.

REFERENCES

¹ S. Tempelaar et al., Chem. Soc. Rev. 2013, 42, 1312-1336

² L. Mespouille et al., Progress in Polymer Science 2014, 39, 1144-1164

³ A. Nachtergael et al., Biomacromolecules 2015, 16 (2), 507-514

⁴ A. Frère et al., Biomacromolecules, 2015, 16 (3), 769-779 

⁵ A. Frère et al., ACS Appl. Mater. Interfaces, 2017, 9 (3), 2181-2195