Abstract
Purpose :
Post-operative scarring following glaucoma filtration surgery is the major obstacle for any long-term surgical success. Therapeutic application of siRNAs is challenging due to sustainability of gene silencing and limits its potential effect. The secreted protein, acidic and rich in cysteine (SPARC) is a protein involved in extracellular matrix (ECM) production and organisation. The purpose of the study is to investigate the sustainability in siRNA silencing by using of a multilayered nanoparticle system for siSPARC in the prevention of fibrosis in a mouse model of conjunctival scarring.
Methods :
Double SPARC siRNA layered layer by layer nanoparticles was fabricated with hydroxyapatite (HA) as the core and poly-L-arginine (ARG) as protective layers (HA|ARG|siRNA|ARG|siRNA|ARG). Modified glaucoma filtration surgeries were performed on 50 mice. At the end of each surgery, mice were injected with either siSPARC-loaded nanoparticles (n=50) or with nanoparticles loaded with scrambled siRNA (n=50). The mice were sacrificed on days 7 and 14, and the conjunctival tissues harvested. qPCR was performed on the tissues to quantify SPARC and collagen I expression. Western blot analysis was also performed on day 7.
Results :
Knock down of SPARC was observed and maintained at 34.25% (P= 0.046) on Day 7 and 36.79% (P = 0.049) on Day 14. Collagen expression was reduced by 47.05% (P = 0.0031) on day 7 and 29.52% (P = 0.047) on Day 14. Both SPARC and collagen I protein expression was decreased on Day 7.
Conclusions :
A multi-layered nanoparticle system provides prolonged siSPARC knock down and a reduction in postoperative fibrosis following experimental glaucoma surgery. Delivery of siRNA using a nanoparticles platform is a promising method for developing sustained siRNA therapeutics for treatment of fibrosis.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.