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- Full-time plan: scientists have made a breakthrough in the gene therapy of hereditary eye diseases
Full-time plan: scientists have made a breakthrough in the gene therapy of hereditary eye diseases
Russian scientists have developed a technology capable of making a breakthrough in the field of domestic gene therapy for hereditary eye diseases. Previously, many such pathologies were considered incurable due to problems with the delivery of large genes. Specialists have learned how to "assemble" large therapeutic proteins inside cells. This will allow a drug with a healthy gene to be injected into the retina of the eye, restoring the functions lost during the mutation. The work opens the way to the creation of high-quality drugs for the treatment of hereditary eye diseases, as well as other serious diseases, in particular Duchenne muscular dystrophy and hereditary deafness. For more information, see the Izvestia article.
Hereditary eye diseases
Scientists from the Gene Therapy department of the Scientific Center for Translational Medicine at Sirius University are working on a large—scale project to develop drugs and technologies for the treatment of hereditary retinopathy, retinal diseases that lead to visual impairment and loss in some cases. The researchers propose to inject a drug with a healthy gene into the retina of the eye, restoring the functions lost during the mutation. This is the most effective way to prevent and slow down the development of diseases.
But one of the main problems with this approach is that many genes associated with inherited retinal diseases are too large and do not fit into standard adeno—associated viruses (AAV), which are the safest and most reliable vectors for delivering genetic material. To solve this problem, Sirius scientists applied the mechanism of protein splicing, a natural process in which special molecules ("inteins") help the two halves of a protein to combine into a single functional molecule.
Hereditary retinal diseases are a group of diseases caused by various rare mutations in the body's genome that lead to severe visual impairment and progressive blindness in childhood and adolescence. In general clinical practice, there are no effective methods for both diagnosis and therapy of such pathologies. In the last few years, there has been great interest and progress in the application of gene therapy methods in ophthalmology.
In the first series of experiments, the researchers tested the technology on the GFP model protein, which is often used in biotechnology because of its convenient fluorescence visualization. The protein was divided into two parts, and then successfully "assembled" back inside human cells using the mechanism of intein trans-splicing. Scientists have shown that the technique works in retinal epithelial cells (ARPE19). Moreover, optimization of the design allowed to increase the efficiency of protein assembly by up to 70%.
Andrey Brovin, a junior researcher at the Gene Therapy Department of the Translational Medicine Research Center
At the second stage, the team (together with colleagues from the Laboratory of Bio- and Chemoinformatics of the National Research University of Higher School of Economics) conducted molecular modeling and mutagenesis of inteins in order to increase the speed and efficiency of the target protein assembly reaction. As a result, it was possible to create an improved system that made it possible to increase the amount of protein collected by one and a half times due to an increase in efficiency up to 80% and reaction speed.
"We have shown that the technology works equally effectively in human and mouse cells, which can be used in replacement therapy to deliver genes that were previously considered too large. We are now focused on verifying the biological safety and therapeutic efficacy of the resulting prototype drug in vivo. If everything is confirmed, then on this basis it will be possible to create new drugs for the treatment of retinopathy and hundreds of other hereditary diseases," Andrei Brovin, a junior researcher at the Gene Therapy department of the Translational Medicine Research Center, a graduate of the first set of postgraduate studies in Molecular Biology at Sirius University, told Izvestia.
A step towards effective genomic therapy
The technology has already been used to create a prototype drug for the treatment of Stargardt's disease, one of the most common forms of hereditary macular degeneration. The developed genetic construct was tested in human cells and animal models: after separate injection of two vectors into the mouse eye, the gene was delivered to retinal photoreceptors, where a therapeutic protein was further assembled, the level of which was twice as high as that of the control in healthy mice.
The approach proposed by the scientists will make it possible to advance towards the treatment of hereditary retinopathy, says Stanislav Stragnov, head of the Laboratory for the Analysis of public health indicators and digitalization of healthcare at MIPT.
"Despite the fact that much more needs to be done before the creation of medicines, and even more so before these drugs become available to patients, laboratory victories are an important step towards clinical victories," the expert said in an interview with Izvestia.
The Sirius team has applied an elegant technology that makes it possible to assemble large therapeutic proteins already inside the cell after the separate delivery of two AAV vectors. This bypasses the key limitation on the volume of the "payload" of these viruses, said Albert Rizvanov, head of the Center for Excellence "Personalized Medicine" at Kazan (Volga Region) Federal University.
— This is especially important for hereditary retinal diseases, and the principle is potentially transferable to other nosologies with "large" genes (Duchenne muscular dystrophy, cystic fibrosis, hemophilia A). Instead of truncated, often less effective options, it is possible to return a full—fledged protein and increase the chances of a clinical effect," he noted.
The limitations of the method are also clear, the specialist emphasized. Two viral vectors need to enter the same cell (otherwise it will receive only half of the instructions), and using a pair of vectors complicates dosing and quality control.
Andrey Brovin, a junior researcher at the Gene Therapy Research Center for Translational Medicine
"In addition, the new protein junctions require a thorough assessment of long—term immune safety. If the relevant preclinical models show sustained recovery of function and a favorable safety profile, the approach can indeed open the way to the treatment of a number of hereditary retinopathy and other genetic diseases where there are still no effective drugs," added Albert Rizvanov.
The research results have been published in two reputable scientific journals Frontiers in Bioengineering and Biotechnology and ACS Bio & Med Chem Au. The research is conducted within the framework of the state program "Science" of the federal territory "Sirius".
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