Development of lipid nanoparticles based on PEG alternatives for efficient siRNA delivery

Over the past few years, the use of small interfering RNA (siRNA), has gained significant
attention as a promising therapeutic approach for addressing complex diseases such
as viral infections, genetic disorders, and cancers. Despite the potential of siRNA, its
clinical application is hindered by several challenges that have been addressed by
employing diverse nanocarriers. Among these nanocarriers, cationic lipid-based
nanoparticles are one of the most used strategies, but the cationic properties are
associated with cytotoxicity and undesired interactions. In this context, ionizable lipid
nanoparticles (LNPs) have emerged as promising alternatives, leading to the
development of the first approved siRNA-based lipid nanoparticles in 2018 (Onpattro®).
To date, Onpattro® remains the only approved siRNA-based lipid nanoparticle drug,
underscoring the existing limitations that impede further clinical advancements. Among
them, polyethylene glycol (PEG) can prolong the half-life of the particles, but may hinder
their efficiency due to a barrier effect (dilemma), and can trigger an immune response
reducing subsequent administrations efficiency (Accelerated Blood Clearance effect).
In this context, the purpose of this work was to develop innovative and more efficient
grafted lipid-based nanoparticles complexing siRNA and using alternatives to PEG.
Moreover, as the limitations that impede the clinical development of these drugs include
the lack of in vitro assay with biological relevance, the purpose was extended to the
development of in vitro assays having enhanced biological relevance.
This work includes the selection and incorporation of amphiphilic poly-N
vinylpyrrolidone (PNVP) polymers used as PEG alternatives into cationic lipoplexes.
PNVP derivatives showed similar benefits to PEG, but reduced in vivo immunogenicity.
Nevertheless, they showed similar dilemma. Hence, poly(N-methyl-N-vinylacetamide)
(PNMVA) amphiphilic polymers were screened and used in lipoplexes, showing similar
benefits to PEG and PNVP polymers, but interestingly avoiding any dilemma.
In the second part of the study, different formulations of LNPs were screened, allowing
to select the most promising ones, showing improved gene silencing efficiency in tumor
cells. Moreover, the selected formulations allowed to confirm the relevance of the
developed NTA in vitro assay to predict their in vivo behavior.
Finally, the selected PNVP and PNMVA derivatives were successfully included in the
promising LNPs, including the switchable CSL3 lipid, and showing more efficient ability
to extinct target protein in tumor cells than lipoplexes. In conclusion, the developed lipid
based nanoparticles incorporating PNVP and PNMVA derivatives exhibit great promise
for enhanced siRNA delivery, even in the context of chronic administration.