Poster O20 - Novel injectable self-assembled system utilizing non-covalent interactions for extended release of nucleic acid nanocarriers to prophylactically treat posterior capsular opacification

Introduction: Posterior capsular opacification (PCO) is the most common postoperative complication of cataract surgery. Current treatment strategies are not geographically accessible everywhere, expensive and pose severe adverse effects. With cataract surgeries projected to double over the next ten years, a prophylactic treat PCO, delivered at the time of surgery, is a considerable unmet need. Previous studies in a rabbit model suggest that a bolus dose of doxorubicin intercalated in DNA nanoconjugates containing the G8 monoclonal antibody (3DNA/Dox/G8), irrigated around the intraocular lens during cataract surgery resulted in the targeted depletion of myofibroblast precursors with minimal off-target effects. However, these studies reported only a short delay in the progression of PCO, instead of overall prevention. To provide extended release of nanocarriers, injectable thermosensitive gels were designed using FDA-approved poly(lactic-co-glycolic acid)-b-poly(ethylene glycol)) (PLGA-PEG-PLGA) triblock copolymers and Poly-L-Lysine (PLL) (US Patent pending, US20200038323A1) . Previously, it has been shown that this formulation transitions into a hydrogel at 35 °C with physical and optical properties suitable for ocular placement. PLL polycations provide multiple non-covalent complexation interactions between the homopolymer and 3DNA conjugates within the nanogel to control release.

Materials and

Methods: Solutions of 10-30% (w/v) PLGA-PEG-PLGA triblock copolymer (d,l-LA/GA ratio of 15/1, PLGA/PEG ratio of 2/1, and PEG with a molecular weight 1,500 Da) and 10-20 mg of PLL chains at a MW of 30-70 kDa were mixed on a tube rotator for 24h at 4°C. Then, the solutions were lyophilized for 24h and reconstituted with G8:3DNA:Dox to final concentrations of 0.3 ng 3DNA/ μL. Rheology and optical clarity were characterized for each sample. Release of nanocarriers from gels was performed in a microfluidic chamber in conditions modeling that of ocular (35 °C) and intraocular flow rates under a set flow rate of ̴3 µL/min. Human rhabdomyosarcoma (RD) cells, selected for their expression of PCO marker brain-specific angiogenesis inhibitor 1 (BAI1), were kept under dynamic media flow and treated with low-dose gel- nanocarrier solutions. Cells were fixed and stained at predetermined time points to evaluate targeted depletion of BAI1+ cells.

Results, Conclusions, and Discussions: Solutions consisting of 10% (w/v) PLGA-PEG-PGLA and 20mg of 30-70kDa transitioned to an optically clear gel at 35°C and sustained release of nanocarriers from the gels for up to 3 months. Incorporating cationic PLL chains of molecular weight in the 30-70kDa range into self-assembled PLGA-PEG-PLGA matrices extended the release of negatively charged DNA-based nanocarriers, compared to previous results using unmodified PLGA-PEG-PLGA gels. We have also shown targeting specificity and cellular depletion sufficient to have therapeutic effects against PCO in vitro, in 28 days.
These findings suggest that extending delivery of a low dose of 3DNA nanocarriers through multiple non-covalent interactions can have therapeutically relevant effects in the prevention of PCO. This system has the potential to impact every cataract surgery patient, decreasing the incidence of PCO and associated complications. Moreover, this gel can be adapted to deliver various other types of therapeutics into the eye.

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