What are the research areas into potential treatments?
Research into effective treatments for Usher syndrome is focused on four main areas: gene therapy, retinal implants, stem cell therapy and drug-based therapy. For the latest news on these and other research, click here.
In 2008, researchers at the University of Pennsylvania and Children’s Hospital of Philadelphia used gene therapy to safely restore vision in three young adults with Leber’s Congenital Amaurosis (LCA), a rare and severe form of congenital blindness. According to Albert Maguire, ophthalmologist at the University of Pennsylvania, “Patients’ vision improved from detecting hand movements to reading lines on an eye chart.” One year later, the patients continue to enjoy the same level of improved vision, and the clinical trials have been expanded to include new patients. For more on this topic, click here.
Many genetic diseases, including Usher syndrome, are caused by a spectrum of different mutations that include a type of mutation called a nonsense mutation. PTC Therapeutics has produced a drug, initially known as PTC 124, now called Ataluren, that has been successful in clinical trials for a subset of patients with Duchenne Muscular Dystrophy and Cystic Fibrosis, who harbor a nonsense mutation. These two diseases have initially been targeted due to their reasonably large patient populations, however, Ataluren may be effective in treating other diseases in which a subset of patients harbor nonsense mutations. A lab in Germany is testing the drug in a mouse model for one of the mutations that can cause Usher 1C via direct administration to retinal cells. For more on this topic, click here.
Usher syndrome 1f is another type of Usher syndrome in which a subset of patients harbor a nonsense mutation. One particular mutation runs in Ashkenazi Jews. Researchers at the Technion in Israel discovered that, like Ataluren, a class of antibiotics, aminoglycosides, can counteract nonsense mutations. Gentamicin is an aminoglycoside. However, continued use of gentamicin is not feasible as, at the constant daily doses that would be required, it would be toxic to humans. Dr. Tamar Ben-Yoseph, a geneticist at the Technion who specializes in Usher Syndrome, collaborated with Professor Timor Baasov of the Chemistry department to modify aminoglycosides to make them safe for humans. The results was NB54, a derivative of gentamicin. The team has been testing NB54 in the lab and is working to obtain an animal model for the next phase of testing. For more on this topic, click here.
The U.S. Department of Energy is funding through 2010, and possibly beyond, the development of an artificial retina. The implant is a collaborative effort between the U.S. government, private industry and research universities. Clinical trials are underway for a 16 and 60 electrode version, The Argus I and II respectively, and development of the next generation with even more electrodes is underway. The implant works similarly to a cochlear implant, with a small camera mounted on glasses that sends a signal to the electrode array implanted on the retina. For more on this topic, click here and here.
Researchers at the Massachusetts Institute of Technology are working a retinal implant that works similarly to the Argus implant with glasses and a camera. The chip will be implanted outside of the retina with only the electrodes attached to the retina. MIT hopes to begin clinical trials in three years. For more on this topic, click here.
Click here to learn about other countries and teams also researching retinal implants.
Stem Cell Therapy
Several researchers are working to use stem cells to create new retinal cells to replace damaged ones. At SUNY Upstate Medical University in Syracuse, N.Y., researchers were able to convert frog stem cells into retinal cells. These cells developed into functioning eyes, enabling the tadpoles to see. For more on this topic, click here.
Researchers at the University of Washington in Seattle are working to use stem cells to replace damaged retinal cells. They have succeeded in creating retinal cells from stem cells and are implanting these cells into blind animal models. For more on this topic, click here.
Advanced Cell Technology (ACT) in Cambridge, MA, working with collaborators at Oregon Health and Science University, have created human embryonic stem cell (hESC)-derived retinal pigment epithelium (RPE). They have already implanted these cells into mouse and other animal models. Robert Lanza, Chief Scientific Officer at ACT, states that the company is preparing to apply to the FDA to begin clinical trials in humans. For more on this topic, click here.
Using a type of skin cells known as human iPS cells, researchers at the University of Wisconsin-Madison School of Medicine and Public Health have successfully grown multiple types of retina cells, paving the way for repairing damaged retinas with new cells grown from the patient’s own skin. For more on this topic, click here.
Ciliary Neurotrophic Factor (CNTF) or NT-501 is a drug-based therapy from Neurotech. Using Encapsulated Cell Technology (ECT), surgeons deliver CNTF directly into the eye via implanted capsules. Phase 2 clinical trials for retinitis pigmentosa are complete. Several patients have experienced improved visual acuity following the implants. The FDA has fast tracked CNTF, meaning that, once clinical trials are complete, the FDA will expedite review of the results. For more on this topic, click here.
Researchers at the Schepens Eye Research Institute in Boston discovered which chemicals in the eye, glutamate and aminoadipate, cause other cells to transform into retinal progenitor cells. These cells are similar to stem cells and regenerate new retinal cells. Testing in the lab and in mice showed that the cells became progenitor cells, migrated to the correct locations in the retinas, and developed into new retinal cells. For more on this topic, click here.