Japanese scientists have used laser light to activate genes delivered to rats' eyes, New Scientist magazine reports. The team, based at the University of Tokyo, says the method will help make gene therapy more effective, by allowing precise control over when and where the therapeutic genes are switched on. The findings are published in the journal Nature Materials.
Gene therapy is the use of genetic material, either DNA or its close chemical relative, RNA, to treat disease symptoms. Some of the challenges facing gene therapy researchers include getting enough of the therapeutic gene into the body tissues where it is needed and controlling the level of protein produced by the inserted gene. The Japanese team has designed a photosensitive complex that can deliver the DNA into the cell, and then release it in response to a pulse of laser light. The researcher tested their approach by delivering DNA to rats eyes, and then activating it with a low power laser.
The complex gets into the cell via a process called endocytosis, in which the cell's outer membrane envelopes the complex and draws it into the cell. The membrane surrounding the complex then 'buds off', leaving it enclosed in a bubble within the cell. When the laser light is used, the photosensitive part of the complex breaks free from the bubble, simultaneously releasing the DNA. According to the researchers, cell death in the treated areas of the eye was minimal, while the activity of the gene delivered to the eye increased by 100 fold.
There is currently much interest in developing gene therapy treatments for eye diseases, since eye cells tend not to divide. This means the effects of the therapy are not so likely to 'grow out', as is the case for tissues made up of actively dividing cells. Also, according to US gene therapy researcher Christopher Norbury of Pennsylvania State University, the immune responses in the eye are less severe than in other tissues.
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