posted on 2024-03-07, 06:29authored byYing Jie Ooi, Chongquan Huang, Kieran Lau, Sing Yian Chew, Jong Gu Park, Mary B. Chan-Park
RNA interference (RNAi)-mediated gene silencing is a
promising
therapeutic approach to treat various diseases, but safe and efficient
delivery remains a major challenge to its clinical application. Non-viral
gene vectors, such as poly(β-amino esters) (pBAEs), have emerged
as a potential candidate due to their biodegradability, low toxicity
profile, ease of synthesis, and high gene transfection efficiency
for both DNA and siRNA delivery. However, achieving significant gene
silencing using pBAEs often requires a large amount of polymer carrier
(with polymer/siRNA weight ratio >100) or high siRNA dose (>100
nM),
which might potentially exacerbate toxicity concerns during delivery.
To overcome these barriers, we designed and optimized a series of
hyperbranched pBAEs capable of efficiently condensing siRNA and achieving
excellent silencing efficiency at a lower polymer/siRNA weight ratio
(w/w) and siRNA dose. Through modulation of monomer combinations and
branching density, we identified the top-performing hyperbranched
pBAEs, named as h(A2B3)-1, which possess good siRNA condensation ability,
low cytotoxicity, and high cellular uptake efficiency. Compared with
Lipofectamine 2000, h(A2B3)-1 achieved lower cytotoxicity and higher
siRNA silencing efficiency in HeLa cells at a polymer/siRNA weight
ratio of 30 and 30 nM siRNA dose. Notably, h(A2B3)-1 enhanced the
gene uptake in primary neural cells and effectively silenced the target
gene in hard-to-transfect primary cortical neurons and oligodendrocyte
progenitor cells, with gene knockdown efficiencies of 34.8 and 53.4%
respectively. By incorporating a bioreducible disulfide compartment
into the polymer backbone, the cytocompatibility of the h(A2B3)-1
was greatly enhanced while maintaining their good transfection efficiency.
Together, the low cytotoxicity and high siRNA transfection efficiency
of hyperbranched h(A2B3)-1 in this study demonstrated their great
potential as a non-viral gene vector for efficient siRNA delivery
and RNAi-mediated gene silencing. This provides valuable insight into
the future development of safe and efficient non-viral siRNA delivery
systems as well as their translation into clinical applications.