| Summary: | The primary cause of failure for minimally invasive glaucoma surgery (MIGS) is fibrosis in the trabecular meshwork (TM) that regulates the outflow of aqueous humour, and no anti-fibrotic drug is available for intraocular use in MIGS. The myocardin-related transcription factor/serum response factor (MRTF/SRF) pathway is a promising anti-fibrotic target. This study aims to utilise a novel lipid nanoparticle (LNP) to deliver MRTF-B siRNA into human TM cells and to compare its effects with those observed in human conjunctival fibroblasts (FF). Two LNP formulations were prepared with and without the targeting peptide c<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">Υ</mi></semantics></math></inline-formula>, and with an siRNA concentration of 50 nM. We examined the biophysical properties and encapsulation efficiencies of the LNPs, and evaluated the effects of <i>MRTF-B</i> silencing on cell viability, key fibrotic genes expression and cell contractility. Both LNP formulations efficiently silenced <i>MRTF-B</i> gene and were non-cytotoxic in TM and FF cells. The presence of c<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">Υ</mi></semantics></math></inline-formula> made the LNPs smaller and more cationic, but had no significant effect on encapsulation efficiency. Both TM and FF cells also showed significantly reduced contractibility after transfection with MRTF-B siRNA LNPs. In TM cells, LNPs with c<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">Υ</mi></semantics></math></inline-formula> achieved a greater decrease in contractility compared to LNPs without c<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">Υ</mi></semantics></math></inline-formula>. In conclusion, we demonstrate that the novel CL4H6-LNPs are able to safely and effectively deliver MRTF-B siRNA into human TM cells. LNPs can serve as a promising non-viral gene therapy to prevent fibrosis in MIGS.
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