Stargardt Disease

Stargardt disease is an inherited disease that leads to blindness. This disease occurs around 1 in every 10,000 children and is an autosomal recessive disease, therefore only being able to trace which parent has it, once the child has been confirmed whether or not to have this disease. It is caused by mascular degeneration, which eventually leads to blindness. Mascular degeneration is where the mascular part of the retina, where there are the most light-receptors, rods and cones (that are used for detecting light and fine focusing of images used in activities such as reading), begin to lose their structure and the rods and cones become less functional, causing the vision of people to degrade from 20/20 to 20/200 or worse. For some cases, there is also a chance of colour blindness, difficulty adapting the eyes to dim environments, blurry sight while having clear peripheral vision and wavy vision. Scientists have confirmed that this is caused by a genetic mutation in the ABCA4 gene, which causes this tissue to begin degrading. It can also be related to
the gene, CNGB3. For mutations in the ABCA4 gene, it causes a build up of vitamin A dimers (bisretinoids) deposits, which are toxic, into the lipofuscin molecules in the retina, which causes mascular deformation. There is also a very rare form of dominant Stargardt’s disease caused by a mutation in the ELOVL4 gene. Currently, there is no cure for Stargardt’s disease, however there is a lot of research revolving around this disease. There are research projects involving gene therapy where is functioning, healthy genes that are injected into the cells that are mutated as well as oral therapy which involves patients in taking medication that prevents the build up of toxic vitamin A dimer deposits. However, there is one ongoing research project that holds a lot of promise: cell therapy. There is a project that Ocata Therapeutics is conducting, using human embryonic stem cells to revert the disease.
The research had begun on April 28th of 2011 when it had received clearance from United States Food and Drug Administration and is currently ongoing. They have taken patients over 18 years old with diagnosed advanced Stargardt’s disease and with visual acuity lower than 20/400 for the worse vision research and 20/100 for higher vision research. They currently have 16 research subjects, undergoing the transplantation of the stem cells into the mascular tissue. They have split the 16 subjects into 5 groups; four groups have low vision (vision worse than 20/400) and have transplanted a range of 50,000 stem cells to 200,000 stem cells with increasing 50,000 intervals between each group. There is currently one group with better vision and 100,000 of the same stem cells have been transplanted into the
retina.
The stem cells that have been transplanted into the patients are MA09-hRPE. The MA09-hRPE are human embryonic stem cells taken from single blastomeric embryos and are differentiated into retinal pigment epithelial cells. These stem cells are hoped to be able to preserve vision as well as improve photoreceptor survival. After four months after the transplant, there have been no signs of tumours forming, hyper-proliferation of cells, formation of tissue in an abnormal place or rejection of the body. The retinal pigment epithelial cells can help retain vision through metabolizing vitamin A and recycling photopigments. The differentiation was undertaken in very specific conditions so that the cells formed is over 99% all retinal pigment epithelial. The cells are then going to be put in a syringe and injected into the retina of the patient’s eye. If this project is successful, it could potentially become a permanent cure for the Stargardt’s disease.