September 9, 2022 -- Using patient-derived retinal organoids, researchers from the National Institutes of Health (NIH) have developed a gene therapy that rescues cilia defects in retinal cells affected by a type of Leber congenital amaurosis (LCA), a disease that causes blindness in early childhood.
The researchers discovered that a type of LCA caused by mutations in the NPHP5 gene leads to severe defects in the primary cilium, which could lead to a potential treatment for this blinding condition.
The research team collected stem cell samples from two patients with NPHP5 deficiency at the NIH Clinical Center and used the samples to generate retinal organoids. Researchers then introduced an adeno-associated viral (AAV) vector containing a functional version of NPHP5 as a gene therapy vehicle and discovered that the retinal organoids showed a significant restoration of opsin protein concentrated in the proper location in outer segments, suggesting that functional NPHP5 may have stabilized the primary cilium gate.
In a healthy retina, photoreceptor outer segments contain light-sensing molecules called opsins. In a healthy eye, NPHP5 protein is believed to sit at a gatelike structure at the base of the primary cilium that helps filter proteins that enter the cilium.
"We've designed a gene therapy approach that could help prevent blindness in children with this disease and one that, with additional research, could perhaps even help treat other effects of the disease," lead investigator Anand Swaroop, PhD, senior investigator at the National Eye Institute's Neurobiology Neurodegeneration and Repair Laboratory, said in a statement.