New mRNA Delivery Platform Restores Muscle Function in DMD Models

Although gene therapy has shown promise for the treatment of Duchenne muscular dystrophy (DMD), the limitations of viral vectors have proven challenging to clinical advancement. Now, a new treatment platform delivered skeletal-muscle-targeted full-length DMD mRNA systemically in a murine model of DMD, successfully restoring the production of dystrophin, and dramatically improve muscle strength, endurance, and function in vivo.

The approach uses allogenically engineered targeting extracellular vesicles (DMD t-EVs)— which offer distinct benefits over current viral-based gene therapies, including reduced side effects and the ability to transfer the entire DMD gene. The researchers engineered the EVs with special tags that directly target skeletal muscles after being injected into the bloodstream. The work also demonstrated the safety and biocompatibility of DMD t-EVs in non-human primates, supporting their translational potential.

“Our new platform overcomes the limitations of current viral-based gene therapies, allowing for the delivery of full-length mRNA, restoring wild-type translation of dystrophin and significantly improving muscle function,” said Betty Kim, MD, PhD, in the department of neurosurgery at UT MD Anderson. “We are highly encouraged by these results, which provide a blueprint for mRNA-loaded EVs as a next-generation therapeutic strategy.”

The study, published today in Nature Biomedical Engineering, is entitled, “Skeletal-muscle-targeted non-viral delivery of full-length DMD mRNA for Duchenne muscular dystrophy.”

DMD is a severe genetic disorder caused by mutations in the DMD gene that prevent dystrophin production, which helps stabilize and protect muscle cells during contractions in healthy individuals. Without dystrophin, the muscles become easily damaged, leading to eventual inflammation and cell death. DMD primarily affects males, with symptoms such as delayed walking and waddling usually appearing in early childhood. As the disease progresses, it leads to loss of walking ability, scoliosis, heart problems and eventual respiratory failure.

Because DMD is the longest known gene in the human genome, current viral-based gene therapies are unable to carry the full length. These limitations result in the loss of the gene’s full function and prevent challenges like dose-limiting toxicities, immune reactions, and other adverse reactions including death.

These side effects have resulted in the removal of at least one Food and Drug Administration-approved gene therapy from the market and are why researchers have been trying to develop alternative ways of safely delivering the full-length DMD gene.

In this study, the researchers loaded the full-length DMD mRNA into EVs that were engineered to specifically target and bind to skeletal muscles. Injection of these mRNA-loaded EVs led to an increase in dystrophin protein expression as well as improved muscle strength and function in preclinical models, with no serious side effects.

Importantly, the treatment stayed on target inside of skeletal muscles and did not trigger any immune responses or toxicities commonly seen with viral-based treatments, even after repeated dosage.

Future studies are needed to determine the full safety of EV-mediated mRNA platforms for clinical trials, including whether they can be delivered to cardiac muscles, as heart conditions are commonly seen in advanced disease. However, based on these results, the authors point out this could be a promising method beyond treating Duchenne muscular dystrophy, also potentially serving as a broader “protein restoration” or cellular reprogramming platform.

“Given that we are now able to replace very large proteins, this platform- and disease-agnostic approach could potentially open doors far beyond rare genetic disorders and traditional gene therapy applications,” Kim said. “It’s possible this could ultimately enable restoration of proteins lost not only through inherited diseases but also from acquired or degenerative processes, including cancer, autoimmune disorders, neurodegeneration, fibrosis and other chronic diseases.”

The post New mRNA Delivery Platform Restores Muscle Function in DMD Models appeared first on GEN – Genetic Engineering and Biotechnology News.