Design and in vitro release study of siRNA loaded Layer by Layer nanoparticles with sustained gene silencing effect

ABSTRACT

Objectives: Clinical translation of siRNA therapeutics has been severely limited due to the lack of stable and sustained siRNA delivery systems. Furthermore, when nanocarrier systems with siRNA are administered systemically to treat diseases, insufficient doses reach the target tissue. Here we report the successful development of a new nanocarrier system for the management of fibrosis.

Methods: The new carrier has a hydroxyapatite core, with alternating layers of siRNA and a cationic peptide. The siRNA used here targets secreted protein acidic and rich in cysteine (SPARC), a key matricellular protein involved in the regulation of collagen fibrillogenesis and assembly. We have also used FRET studies to elucidate the fate of the particles inside cells, including the mechanistic details of layer-by-layer detachment.

Results: In vitro studies using murine conjunctiva fibroblasts show sustained release over 2 weeks, and that such released siRNA sustained SPARC knockdown without affecting cell growth, and maintained siRNA presence in the cells for at least two weeks with a single-dose treatment. Release studies of siRNA from particles in vitro gave insight on how the particles delivered prolonged gene-silencing effects.

Conclusion: A single treatment of the layer-by-layer nanoparticle designed can achieve sustained gene silencing over 2 weeks. Localized delivery of stabilized siRNA with sustained-release capabilities opens the door for many other applications of siRNA-based gene regulation.

KEYWORDS:

• Layer-by-layer nanoparticles
• siRNA delivery
• fibrosis
• drug release
• mechanism

Article highlights

• Clinical translation of siRNA therapeutics has been severely limited due to the lack of stable and sustained siRNA delivery systems

• When nanocarrier systems with siRNA are administered systemically to treat diseases, insufficient doses reach the target tissue

• A multilayered Layer by Layer hydroxyapatite-cored nanoparticle system has been developed to locally deliver siRNA with sustained gene silencing effect.

• In Vitro studies showed a single dose of the designed siRNA loaded nanoparticles induced gene silencing over 2 weeks with no toxicity effect to murine conjunctival cells.

• Release study conducted to observe particle breakdown behavior within cells suggested that Layer by Layer nanoparticles disassemble layer by layer starting with the outermost layers.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Supplementary material

Supplementary data for this article can be accessed here.

Additional information

Funding

This work was funded by a Clinician Scientist Award grant (NMRC/CSA-SI/0001/2015) and by the Singapore National Research Foundation under its Translational and Clinical Research (TCR) Program (NMRC/TCR/002-SERI/2008; NMRC/TCR/008-SERI/2013) to TTW, both administered by the Singapore Ministry of Health’s National Medical Research Council.