Gene therapy is a relatively new and much heralded therapeutic approach. But despite the advances in molecular genetics, attempts to target organs or particular body structures using the technique have proved disappointing. The problem appears to hinge on the vector agent that is used to target cellular DNA. It must be capable of successfully delivering a genetic sequence and at the same time be able to withstand the receiving body's immune system response.
The researchers studied newborn rats with induced retinopathy of prematurity. This is a disease which is on the increase as a result of the rising numbers of surviving premature babies. It is a leading cause of blindness and defective vision in children, and despite surgical advances, around half of babies with the most severe form of the disease will become blind. Disordered blood vessel growth from the retina needs to be prevented in order to treat the disease.
The researchers tested the ability of four different viruses, adenovirus, bovine smallpox virus, herpes virus, and a virus that causes leukaemia, the murine leukaemia virus, to transport genetic material into the defective eyes of 18 day old rats.
The results showed that adenovirus was the most effective vector, and furthermore it specifically targeted tissues in the jelly-like material inside the eyeball which destroy vital developing eye tissues. Delicate adjacent nerve tissues risk being damaged if the target is not specific.
The research is in its early stages, say the authors, but they suggest that this is a first step in the use of gene therapy for both treatment and research purposes.
Dr Itay Chowers, Department of Ophthalmology, Hadassah University Hospital, Hadassah, Israel.
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