Herpes simplex virus mediated gene transfer to primate ocular tissues

Area of Science:

• Ophthalmology
• Gene Therapy
• Virology

Background:

• Gene therapy holds promise for treating ocular diseases.
• Herpes simplex virus (HSV) vectors are being explored for ocular gene delivery.
• Replication-competent HSV vectors offer potential for sustained transgene expression.

Purpose of the Study:

• To assess the feasibility of gene delivery into monkey eyes using a replication-competent HSV-1 mutant (hrR3).
• To evaluate in vitro and in vivo gene transfer efficiency and distribution in ocular tissues.
• To identify potential limitations for clinical application.

Main Methods:

• Infection of cultured human trabecular meshwork (HTM) and human ciliary muscle (HCM) cells with hrR3 expressing lacZ.
• Histochemical detection of beta-galactosidase activity in vitro.
• Intracameral and intravitreal injection of hrR3 into cynomolgus monkey eyes.
• Evaluation of lacZ expression and inflammatory responses in vivo.

Main Results:

• hrR3 mediated dose-dependent lacZ expression in cultured HTM and HCM cells.
• In vivo, transgene expression was observed in trabecular meshwork (TM) and non-pigmented ciliary epithelial (NPE) cells.
• Expression was also detected in retinal pigmented epithelial (RPE) and retinal ganglion cells (RGC).
• Significant inflammation occurred in the anterior chamber, TM, and ciliary muscle, with mild vitritis and retinitis.

Conclusions:

• The hrR3 vector demonstrates successful gene transfer into human ocular cells and monkey ocular tissues.
• Inflammation, potential cytotoxicity, and limited transgene expression duration require further investigation.
• The technique's clinical applicability necessitates addressing the observed inflammatory responses.