Durable, safe, multi-gene lentiviral vector expression in feline trabecular meshwork

Area of Science:

• Ophthalmology
• Gene Therapy
• Molecular Biology

Background:

• Elevated intraocular pressure (IOP) is the primary risk factor for primary open angle glaucoma (POAG).
• Gene therapy offers potential for permanent correction of elevated IOP by targeting the trabecular meshwork (TM), the eye's outflow pathway.
• Developing safe and effective gene delivery methods to the TM is crucial for POAG treatment.

Purpose of the Study:

• To evaluate lentiviral vector designs and doses for long-term transgene expression in the feline TM.
• To investigate the effect of myocilin protein expression on IOP in a large animal model.
• To establish a robust experimental system for testing POAG therapeutic genes.

Main Methods:

• Dual-gene feline immunodeficiency virus (FIV) vectors were injected into the anterior chambers of domestic cats (n=36 eyes).
• Transgene expression (enhanced GFP) in the TM was monitored non-invasively in vivo and confirmed post-mortem.
• Myocilin or a mutant myocilin was co-expressed with GFP to assess IOP effects.

Main Results:

• Sustained, well-tolerated enhanced GFP expression in the TM was achieved for 1.2-2.3 years.
• Post-mortem analysis confirmed substantial TM transgene expression, often exceeding in vivo observations.
• Co-expression of myocilin or mutant myocilin did not lead to elevated IOP.

Conclusions:

• Safe and durable single and dual gene expression in the feline TM is feasible using FIV vectors.
• This study validates a large animal model for testing gene-based therapies for POAG.
• The findings support the potential of gene therapy for managing elevated IOP in glaucoma.