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Yang Fei Tan, Li-Fong Seet, Subbu S Venkatraman, Tina T Wong; A single dose of layer-by-layer nanoparticles prolongs endogenous gene silencing for the treatment of fibrosis. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4950.
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Fibrosis is a progressive process requiring sustained inhibition for successful treatment. The purpose of the study is to evaluate the first example of using multi-layered nanoparticles to extend the anti-fibrotic effect by endogenous gene silencing in a single dose, establishing a method for safe and effective treatment of fibrosis.
SPARC siRNA loaded layer by layer nanoparticles was fabricated with hydroxyapatite (HA) as the core and poly-L-arginine (ARG) as protective layers in an optimised configuration targeted at sustained gene silencing. Modified glaucoma filtration surgeries were performed on 60 mice. Mice were then injected with either siSPARC or scrambled siRNA-loaded nanoparticles (n=60). The mice were sacrificed on days 7 and 14, and the conjunctival tissues harvested. Immunoblotting was performed on the tissues to quantify SPARC and collagen I protein levels. Annexin V in conjunctival tissues was measured by flow cytometry to evaluate toxicity of the particles in vivo. Picrosirius red and immunofluorescence of cryosections of 14 day-old treated eye tissues were also performed to evaluate amount of collagen present and toxicity of the treatment.
SPARC protein levels reduced by 1.18 folds on day 7 and 1.79 folds on day 14 relative to control samples. Collagen protein levels reduced by 2.35 folds on day 7, and 1.67 folds on day 14, relative to controls. Annexin V levels and histological immunofluorescence cryosections showed no significant toxicity of the treatments in vivo. Picrosirius red stained cryosections showed particles surrounded by collagen fibres of similar amount and maturity as areas without particles, further proving insignificant toxicity of treatment.
SPARC silencing with the multi-layered nanoparticle system reduced collagen expression for 14 days and no significant local toxicity was observed. Delivery of siRNA using this nanoparticles platform is a promising alternative for the treatment of fibrosis.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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