The researchers plan to deliver the MERTK gene in a viral vector - a carrier commonly used to deliver genetic material to treat these cells in order to restore function of photoreceptors. Using a rodent model of RP with a similar MERTK mutation, the researchers have demonstrated in proof-of-concept studies that viral vector delivery of MERTK corrects the mutant gene and restores vision.

The eye is an ideal place for gene therapy because it's an "immune-privileged site," meaning that the eye is able to tolerate the introduction of foreign cells with a minimal, if any, inflammatory immune response, according to Zhang.

The research team's next step is to show that such gene therapy is safe in further animal studies, to be conducted in China, along with additional rat studies that will be conducted at UC San Diego and at the University of Florida.

Once safety for the procedure has been shown, the team hopes to proceed to a human clinical trial in seven patients identified in Saudi Arabia, perhaps as early as spring of 2010.

The same type of vector has been successfully tested in both animals and humans for a similar type of early-onset retinal degeneration called Leber's congenital amaurosis.

Additional investigators include William Hauswirth, PhD, at the University of Florida, Gainesville; SriniVas Sadda, MD, at Doheny Eye Institute, University of Southern California; Emad Abboud, MD, and Hisham Alkuraya, MD, at King Khaled Eye Specialist Hospital, Saudi Arabia; and Peiquan Chao, MD, PhD, Department of Ophthalmology, Shanghai Jiaotong University.

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