Glaucoma is a leading cause of irreversible blindness in humans and dogs. Increased intraocular pressure (IOP) due to abnormal aqueous humor outflow through the trabecular meshwork (TM) is a major risk factor and is based on genetic predisposition. The purposes of these studies were to target gene expression to the canine TM and prevent or reverse IOP elevation in beagle dogs with inherited primary open angle glaucoma (POAG). In these animals, the disease is caused by a missense mutation in the ADAMTS10 gene. Green fluorescent protein (GFP) reporter gene expression was successfully targeted to the conventional aqueous humor outflow pathway of wild type and ADAMTS10-mutant dogs using a non-self-complementary adeno-associated virus serotype 2 (AAV2) with a single capsid mutation: AAV2(Y444F)-smCBA-GFP (2 x 1010 vg/mL to 2 x 1012 vg/mL; 50 μL). The triple (Y444,500,730F) and quadruple (Y444,500,730F + T491V) mutant AAV2s were ineffective. Subsequent gene replacement therapy was performed in pre-glaucomatous (n=7) and glaucomatous (n=3) ADAMTS10-mutants with AAV2(Y444F)-smCBA-hADAMTS10 at the highest dose (2 x 1012 vg/mL; 50 μL). The IOP of these animals were monitored weekly for 19 weeks. While the treatment was deemed safe with no severe adverse effects, a decrease in IOP was not observed. If the transgene was expressed, a therapeutic effect could probably be achieved by increasing the vector dose and number of transduced TM cells.
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