A research team at Sirius University of Science and Technology has presented an improved approach to gene therapy for Leber hereditary optic neuropathy – a severe mitochondrial disease that causes rapid and often irreversible vision loss. The work focuses on optimising the delivery of the therapeutic gene encoding the ND4 protein into cell mitochondria, which could significantly enhance the efficacy of future treatments for one of the most common forms of inherited blindness. The findings were published in the international journal Frontiers in Bioengineering and Biotechnology.
In the study, Sirius scientists tested five different mitochondrial targeting sequences (MTS) responsible for transporting the therapeutic ND4 protein to its site of action. The most effective was the MTS-cox8k sequence. Using this construct in a cellular model significantly restored mitochondrial function: reactive oxygen species levels fell by 72%, mitochondrial calcium content decreased by 47%, and mitochondrial membrane potential increased by 38%. These results indicate a marked reduction in cellular stress and partial restoration of energy metabolism.
“In Leber neuropathy patients, the mutation disrupts the mitochondrial respiratory chain, triggering a cascade of damage and leading to retinal cell death. We delivered a functional copy of the ND4-encoding gene into the cell nucleus and directed its product to the mitochondria. Our goal is to create a real therapeutic product for patients,” said Evgeny Lapshin, junior researcher in the Gene Therapy division at the Scientific Centre for Translational Medicine and a graduate of the master’s programme in Genetics and Genetic Technologies at Sirius University.
The study showed that the choice of targeting sequence plays a critical role in therapeutic success. There is no universal solution for delivering mitochondrial proteins: efficacy depends directly on the structure of the specific protein, so each disease may require separate optimisation.
The results demonstrate that one cannot use a random mitochondrial transporter, the scientists noted. Each therapeutic protein requires individual screening. This, they said, paves the way for the development of more precise and effective treatments for various mitochondrial diseases.
The next phase of research will involve testing on neuronal models, including retinal ganglion cells derived from patient-specific induced pluripotent stem cells, as well as preclinical studies in animal models to assess the safety and efficacy of viral delivery.
Although the technology is still at the preclinical stage, the work is already seen as an important step towards the next generation of gene therapy for Leber hereditary optic neuropathy. Because the study focuses on optimising an existing therapeutic approach rather than creating an entirely new platform, the transition to clinical application could potentially be accelerated.