Amphiphilic Poly[(propylene glycol)‐block‐(2‐methyl‐2‐oxazoline)] Copolymers for Gene Transfer in Skeletal Muscle

Abstract

Amphiphilic triblock copolymers such as poly(ethylene glycol-b-propylene glycol-b-ethylene glycol) PE6400 (PEG(13)-PPG(30)-PEG(13)) have been recently shown to promote gene transfer in muscle. Herein we investigated the effect of a chemical change of the PEG moiety on the transfection activity of these compounds. We synthesized new amphiphilic copolymers in which the PEG end blocks are replaced by more hydrophilic poly(2-methyl-2-oxazoline) (PMeOxz) chains of various lengths. The resulting triblock PMeOxz-PPG-PMeOxz compounds were characterized by NMR, SEC, TGA, and DSC techniques and assayed for in vivo muscle gene transfer. The results confirm both the block structure and the monomer unit composition (DP(PG)/DP(MeOxz)) of the new PPG(34)-PMeOxz(41) and PPG(34)-PMeOxz(21) triblock copolymers. Furthermore, in vivo experiments show that these copolymers are able to significantly increase DNA transfection efficiency, despite the fact that their chemical nature and hydrophilic character are different from the poloxamers. Overall, these results show that the capacity to enhance DNA transfection in skeletal muscle is not restricted to PEG-PPG-PEG arrangements.

Synthesis and Evaluation of Amphiphilic Poly(tetrahydrofuran-b-ethylene oxide) Copolymers for DNA Delivery into Skeletal Muscle

“…The expression levels of luciferase 30 h after transfection indicate that neither CP1 nor CP2 could promote gene transfer (not shown). Taken together, these results are in good agreement with reports using commercially available pEO-pPO-pEO poloxamers or pMeOXZ-pPO-pMeOXZ copolymers (15). Indeed, studies conducted for example with Pluronic L64 could not demonstrate an interaction between the copolymer and DNA (8) nor was the polymer able to mediate gene transfer in vitro (8).…”

“…Altogether, the present results and others (15) indicate that there is a significant flexibility in terms of design of new amphiphilic triblock for improving transfection and/or safety properties. This structural flexibility appears intriguing, and raises the question of how these polymers promote transgene expression.…”

Design Strategies for Functionalized Poly(2-oxazoline)s and Derived Materials

“…In solution, the tadpole-shaped pMeOx formed crooked nanowires. Guis et al investigated pMeOx-block-poly(propylene glycol)-block-pMeOx triblock copolymers as possible alternative to poly(ethylene glycol)-block-poly(propylene glycol)-blockpoly(ethylene glycol) compounds especially for the use in in vivo muscle gene transfer and found that the DNA transfection efficacy could be increased using these compounds [48]. For the synthesis, Guis et al used ditosylated poly(propylene glycol) macroinitiators to initiate the CROP of MeOx.…”

Biocompatibility and Immunocompatibility Assessment of Poly(2-Oxazolines)

“…Successful gene delivery systems with high transfection efficiency was prepared also by condensation of therapeutic DNA with different copolymers of poly(L-lysine)-graft-poly(2-methyl-2-oxazoline) of variable grafting densities [43]. Amphiphilic poly[(propylene glycol)-block-(2-methyl-2-oxazoine)] block copolymers were studied for gene transfer in skeletal muscle [44].…”