posted on 2022-02-02, 16:22authored byXinlong Liu, Fei Ding, Yuanyuan Guo, Kai Jiang, Yucheng Fu, Lijuan Zhu, Ming Li, Xinyuan Zhu, Chuan Zhang
Small
interfering RNA (siRNA) has been emerging as a highly selective
and effective pharmaceutics for treating broad classes of diseases.
However, the practical application of siRNA agent is often hampered
by its poor crossing of the cellular membrane barrier and ineffective
releasing from endosome to cytoplasm, leading to low gene silencing
efficacy for clinical purposes. Thus far, cationic lipid and polymer-based
vectors have been extensively explored for gene delivery. Yet condensing
the rigid and highly negatively charged siRNA duplex to form a stable
complex vehicle usually requires a large load of cationic carriers,
prone to raising the toxicity issue for delivery. Herein, we develop
a simple strategy that can efficiently condense the siRNAs into nanoparticle
vehicles for target gene regulation. In this approach, we first employ
a DNA-grafted polycaprolactone (DNA-g-PCL) brush
as template to organize the small rigid siRNAs into a large brush-like
structure (siRNA-brush) through nucleic acid hybridization. Then,
the siRNA-brush assembly is condensed by an ionizable and biodegradable
polymer (poly(β-amino ester), PBAE) under acidic buffer condition
to form a stable nanoparticle for siRNA delivery. Compared to the
free siRNAs with poor complexing capability with PBAE, the large brush-like
siRNA assemblies with more complicated topological architecture significantly
promotes their electrostatic interaction with PBAE, enabling the formation
of complexed nanoparticles at low weight ratio of polymer to siRNA.
Additionally, PBAE/siRNA-brush complexes exhibit good biocompatibility
and stability under physiological condition, as well as enhanced cellular
internalization. When equipped with functional siRNAs, the obtained
delivery system demonstrates excellent downregulation of target genes
both in vitro and in vivo, through which the progression of hypertrophic
scars can be retarded with negligible adverse effects in an xenografted
mouse model.