The activation of endogenous full-length utrophin shows promise for treating Duchenne muscular dystrophy (DMD), according to a study recently published in Nature Communications.
DMD is a disease that is driven by mutations in the gene that codes dystrophin, a protein that protects muscle cells from daily damage. Endogenous utrophin is a naturally produced protein that plays an important role in muscle membrane stability and structure. Studies indicate that it can make up for a lack of dystrophin.
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The authors of the study first developed a method to activate endogenous utrophin in mouse models, which they termed MyoAAV-delivered utrophin activator (MyoAAV-UA). The research team then examined the effectiveness of MyoAAV-UA as a utrophin activation system in two DMD mouse models that each had different mutations that caused DMD-related muscle symptoms.
Researchers injected MyoAAV-UA into these mice and extracted and analyzed muscle tissue and various organ samples four weeks later. They discovered that viral genome copies were more abundant in muscle tissue compared to non-muscle tissue; this indicated that MyoAAV-UA had muscle specificity, which is desirable in DMD. This meant the administration of MyoAAV-UA successfully led to a pronounced increase in utrophin expression.
After utrophin expression was confirmed, the authors of the study sought to investigate if DMD-associated symptoms were reduced. Six months after treatment, the group of mice that received MyoAAV-UA continued to exhibit elevated utrophin expression in the muscles, with improved myofiber integrity and alignment, alongside reduced fibrosis.
“Given that 6 months represents a relatively long period in the lifespan of a mouse, this timeframe might be considered as a substantial therapeutic window in humans,” the study’s authors noted.
In addition, researchers discovered that the activation of endogenous utrophin was effective in slowing the deterioration of heart function in treated mice.
In conclusion, scientists discovered that the pharmacological activation of endogenous utrophin using a novel delivery system resulted in significant improvements in the muscle condition of DMD mouse models. This therapeutic strategy may yield promising results if it can be shown to be effective and safe in human subjects.
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