Researchers have created nanoparticles that might be used for effective gene therapy for macular degeneration. If successful, this effort may greatly expand the growing number and effectiveness of gene therapies for eye diseases.
News-Medical reports that many vision problems have improved with the help of genetic material delivered to cells of the eye that result in the production of beneficial proteins. Modified viruses deliver this DNA material after being injected into the eye.
Good viruses are attacked by the immune system
A problem with this approach is the body can develop an immune response to these viruses. The immune system starts destroying these viruses, so repeated treatments are needed, resulting in multiple eye injections for patients. As time goes on, they become less effective because the patient’s antibodies attack gene-carrying viruses.
Engineers and ophthalmologists are working to overcome this problem, including developing a treatment for wet age-related macular degeneration (AMD). This is a common disease where abnormal blood vessel growth damages light-sensitive tissue in the back of the eye.
How can you deliver an effective macular degeneration treatment on a microscopic scale?
A team at the Johns Hopkins University School of Medicine has developed nanoparticles that can deliver this genetic information, which can lead to the creation of proteins that can treat AMD. A nanoparticle is a particle between about one and a hundred nanometers in size. A nanometer is one-millionth of a millimeter. A sheet of paper is about 100,000 nanometers thick.
Immune systems of rats used in experiments have ignored nanoparticles and there doesn’t appear to have been antibodies attacking the particles. The nanoparticles were very efficient in bringing genes into eye cells where they made large quantities of protein. The protein production lasted for at least eight months, a significant improvement over existing treatments where proteins are injected into patients every one to two months.
One test used a gene that makes vascular endothelial growth factor (VEGF). It results in the growth of new blood vessels in the eye. If there is too much VEGF, there are too many blood vessels in the retina which block vision. This is what happens to those with wet AMD.
The researchers injected the eyes of 30 rats with the nanoparticles carrying the VEGF gene. The rats developed abnormal blood vessels a month after the injections. They continued to grow two to five months after ab injection. Scarring occurred under the retina similar to what happens with those with untreated wet AMD.
Researchers then injected a nanoparticle carrying another gene that makes a protein that inhibits VEGF. Three weeks after these injections, the mice had a 60% reduction in abnormal blood vessels compared to control mice.
Research showed nanoparticles can deliver genes that produce beneficial proteins for many months. If this works in humans, the protein wouldn’t need to be repeatedly injected into patients because genetic instructions to the eyes to create their own protein. The nanoparticles used in the process, unlike the modified viruses currently used, wouldn’t be destroyed by the immune system.
The research team is working on using nanoparticles to treat patients with reduced or no vision due to other genetic defects where blindness occurs because of a defective inherited gene. They hope the response with the use of nanoparticles will allow the introduction of functional versions of genes that inherited harmful mutations, resulting in normal vision in patients.
The Lehigh Valley Center for Sight is here to help
If you have questions about AMD or fear that you may have the condition, contact the Lehigh Valley Center for Sight at 610-437-4988 or fill out our contact form so we can start the conversation and work together to protect your sight and your ability to live your life.
Houman Ahdieh, MD
Lehigh Valley Center for Sight
https://www.lvcenter4sight.com
eyedoc@lvcenter4sight.com
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